Genetic Analysis of Founder Bottlenecks in the Rare British Butterfly Plebejus argus. Analisis Genetico de Cuellos de Botella en la Mariposa Britanica Plebejus argus - Martin I. Brookes; Yvonne A. Graneau; Peter King; Owen C. Rose; Chris D. Thomas; James L. B. Mallet (Conservation Biology, 1997)

Effects of Harvesting on Genetic Diversity in Old-Growth Eastern White Pine in Ontario, Canada. Efecto de la Cosecha Sobre la Diversidad Genetica de un Bosque Maduro de Pino Blanco del Este - George P. Buchert; Om P. Rajora; James V. Hood; Bruce P. Dancik (Conservation Biology, 1997)

Survival and Recruitment of Captive-Reared and Wild-Reared Takahe in Fiordland, New Zealand. Sobrevivencia y Reclutamineto del Takahe Obtenido en Cautiverio y en Condiciones Silvestres en Fiordland, Nueva Zelanda - Jane M. Maxwell; Ian G. Jamieson (Conservation Biology, 1997)

The Agroecosystem: A Need for the Conservation Biologist's Lens - John Vandermeer; Ivette Perfecto (Conservation Biology, 1997)

Architecture as Pedagogy II - David W. Orr (Conservation Biology, 1997)

Local Extinctions of Plants in Remnants of Extensively Used Calcareous Grasslands 1950 -1985. Extinciones Locales de Plantas en Remanentes de Pastizales Calcareos de Uso extensivo entre 1950 y 1985 - Markus Fischer; Jurg Stocklin (Conservation Biology, 1997)

Saving the Tiger: More Money or Less Power? - Vasant K. Saberwal (Conservation Biology, 1997)

Future Climate in the Yellowstone National Park Region and Its Potential Impact on Vegetation. Clima Futuro en la Region del Parque Nacional de Yellowstone y su Potencial Impacto Sobre la Vegetacion - Patrick J. Bartlein; Cathy Whitlock; Sarah L. Shafer (Conservation Biology, 1997)

Inf luence of Season and a Sympatric Congener on Habitat Use by Stephens' Kangaroo Rat. Influencia Estacional y de un Congenere Simpatrico en el Uso de Habitat de la Rata Canguro de Stephen - Ross L. Goldingay thinsp; Mary V. Price (Conservation Biology, 1997)

Captive Breeding, Zoos, and Good Sense - Spartaco Gippoliti; Giuseppe Maria Carpaneto (Conservation Biology, 1997)

Genetic Analyses to Establish Captive Breeding Priorities for Endangered Snake River Sockeye Salmon. Analisis Genetico para Establecer Prioridades de Reproduccion en Cautiverio para el Salmon Sockeye del Snake River en Piligro de Extincion - Shawn A. Cummings; Ernest L. Brannon; Karen J. Adams; Gary H. Thorgaard (Conservation Biology, 1997)

Avoiding Paper Tigers and Saving Real Tigers: Response to Saberwal - K. Ullas Karanth; M. D. Madhusudan (Conservation Biology, 1997)

Reproductive Success Increases with Local Density of Conspecif ics in a Desert Mustard (Lesquerella fendleri). El Exito Reproductivo Incrementa con la Densidad Local de Coespecificos en la Mostaza del Desierto (Lesquerella fendleri) - Julia Roll; Randall J. Mitchell; Robert J. Cabin; Diane L. Marshall (Conservation Biology, 1997)

Limitations of Captive Breeding: Reply to Gippoliti and Carpaneto - Noel F. R. Snyder; Scott R. Derrickson; Steven R. Beissinger; James W. Wiley; Thomas B. Smith; William D. Toone; Brian Miller (Conservation Biology, 1997)

Public Attitudes and Knowledge about Ecosystem Management on Department of Defense Land in Florida. Actidudes Publicas y Conocimiento del Manejo de Ecosistemas de las Tierras del Departamento de Defensa en Florida - Susan K. Jacobson; Susan B. Marynowski (Conservation Biology, 1997)

Historical Distribution of the Extinct Tropical Seal, Monachus tropicalis (Carnivora: Phocidae) - Robert M. Timm; Rosa M. Salazar; A. Townsend Peterson (Conservation Biology, 1997)

Future Taxonomic Partnerships: Reply to Goldstein - Ian Oliver; Andrew J. Beattie (Conservation Biology, 1997)

Deforestation Predicts the Number of Threatened Birds in Insular Southeast Asia - Thomas M. Brooks; Stuart L. Pimm; Nigel J. Collar (Conservation Biology, 1997)
The world’s tropical forests are being cleared rapidly, and ecologists claim this is causing a massive loss of species. This claim has its critics. Can we predict extinctions from the extent of deforestation? We mapped the percentage of deforestation on the islands of the Philippines and Indonesia and counted the number of bird species found only on these islands. We then used the species‐area relationship to calculate the number of species predicted to become globally extinct following deforestation on these islands. Next, we counted the numbers of insular southeast Asian endemic bird species considered threatened—i.e., those having “a high probability of extinction in the wild in the medium‐term future”—in the latest summary Red Data Book. The numbers of extinctions predicted from deforestation and the numbers of species actually threatened are strikingly similar. This suggests we can estimate the size of the extinction crisis in once‐forested regions from the extent of deforestation. The numbers of extinctions will be large. Without rapid and effective conservation, many of the species endemic to insular southeast Asia will soon be lost.

Miguel Alvarez del Toro: First and Last of a Kind - Alfredo D. Cuarón (Conservation Biology, 1997)

Breeding Bird Abundance in an Urbanizing Landscape in Coastal Southern California - Douglas T. Bolger; Thomas A. Scott; John T. Rotenberry (Conservation Biology, 1997)
The relative influence of local versus landscape heterogeneity on species abundance is an important consideration in the design and management of nature reserves in heterogeneous landscapes. We described the spatial patterns of resident breeding bird abundance at a landscape scale in an urbanizing landscape gradient in coastal San Diego County, California (USA). The gradient spanned approximately 260 km 2 and included a large, mostly contiguous block of undeveloped shrub habitat mosaic which graded into an area of internally fragmented habitat and finally into an area characterized by discrete patches of habitat in an urban matrix. We quantified the distribution of resident bird species in this landscape with point counts and used stepwise logistic regression and canonical correspondence analysis to explore the relative strengths of association between bird abundance and local habitat variation versus landscape variation for the 20 most common bird species. We measured local habitat conditions in a 100‐m radius around each point count station. Landscape variables were extracted from a GIS database of this region and included habitat patch size, distance to developed edge, and two indices of urban exposure. The addition of landscape variables to stepwise logistic regression analyses substantially improved the predictive power of the resulting models in 14 of 20 species. Model concordance (the ability of the model to correctly classify all pairs of divergent sites) increased from a mean of 56% without landscape variables to 76% when one or more landscape variables were selected for inclusion in the final model. Response of the 20 focal species to the landscape gradient differed markedly among species. Canonical correspondence analysis was used to rank species along a landscape response gradient from edge/fragmentation reduced species to edge/fragmentation enhanced species. The four species exhibiting the most edge/fragmentation reduced pattern were sparrows: Sage (Amphispiza belli), Rufous‐crowned (Aimophila ruficeps), Lark (Chondestes grammacus), and Black‐chinned sparrows (Spizella atrogularis). Costa’s Hummingbird (Calypte costae) also showed a pattern of edge/fragmentation reduction. The opposite end of the gradient was occupied by species whose densities are elevated near edges and in fragmented areas. The middle of the gradient was occupied by species that were abundant, widely distributed, and showed no sensitivity to landscape position or shrub habitat type. The abundance of edge/fragmentation reduced species appears to be depressed within 200 to 500 m of an edge and the abundance of the edge/fragmentation enhanced species is elevated up to 1000 m from an edge, depending on the species. Conservation analyses, including GAP analysis, often assume that the relationship between species abundance and habitat is invariant with landscape position. In heterogeneous landscapes these analyses may underestimate the conservation risk to species in the edge/fragmentation sensitive category because their abundance varies strongly with landscape location.

Low Genetic Variability in the Hawaiian Monk Seal - Maria B. Kretzmann; William G. Gilmartin; Axel Meyer; Gerard P. Zegers; Steven R. Fain; Bruce F. Taylor; Daniel P. Costa (Conservation Biology, 1997)
The Hawaiian monk seal ( Monachus schauinslandi) is a critically endangered species that has failed to recover from human exploitation despite decades of protection and ongoing management efforts designed to increase population growth. The seals breed at five principal locations in the northwestern Hawaiian islands, and inter‐island migration is limited. Genetic variation in this species is expected to be low due to a recent population bottleneck and probable inbreeding within small subpopulations. To test the hypothesis that small population size and strong site fidelity has led to low within‐island genetic variability and significant between‐island differentiation, we used two independent approaches to quantify genetic variation both within and among the principal subpopulations. Mitochondrial control region and tRNA gene sequences (359 base pairs) were obtained from 50 seals and revealed very low genetic diversity (0.6% variable sites), with no evidence of subpopulation differentiation. Multilocus DNA fingerprints from 22 individuals also indicated low genetic variation in at least some subpopulations (band‐sharing values for “unrelated” seals from the same island ranged from 49 to 73%). This method also provided preliminary evidence of population subdivision ( F′ st estimates of 0.20 and 0.13 for two adjacent island pairs). Translocations of seals among islands may therefore have the potential to relieve local inbreeding and possibly to reduce the total amount of variation preserved in the population. Genetic variation is only one of many factors that determine the ability of an endangered species to recover. Maintenance of existing genetic diversity, however, remains an important priority for conservation programs because of the possibility of increased disease resistance in more variable populations and the chance that inbreeding depression may only be manifest under adverse environmental conditions.

Genetic Diversity of Lepilemur mustelinus ruficaudatus , a Nocturnal Lemur of Madagascar - Jürgen Tomiuk; Lutz Bachmann; Michael Leipoldt; Jörg U. Ganzhorn; Reiner Ries; Michaela Weis; Volker Loeschcke (Conservation Biology, 1997)
The genetic polymorphism of natural populations of Lepilemur mustelinus ruficaudatus was studied by protein electrophoresis. We sampled blood from 72 individuals from four populations separated by geographic or anthropogenic barriers from southwestern Madagascar. Six out of 22 enzyme loci showed genetic variation with a degree of polymorphism of 0.273. The expected and observed degree of genetic heterozygosity over all loci is similar to that of other primates (H e = 0.058, H o = 0.036). The F‐statistics revealed that the four subpopulations were similar with respect to gene structure (F ST = 0.065, p = 0.016), but the genotypic structures within subpopulations were inconsistent with random mating. For the total of the four subpopulations the proportion of heterozygous individuals was significantly smaller than expected under random mating (F IS = 0.373, F IT = 0.414, p

Effects of Land‐Use and Tsetse Fly Control on Bird Species Richness in Southwestern Ethiopia - Cathleen J. Wilson; Robin S. Reid; Nancy L. Stanton; Brian D. Perry (Conservation Biology, 1997)
Successful control of tsetse (Glossina spp.)‐transmitted trypanosomiasis in the Ghibe Valley, Ethiopia, appears to have accelerated conversion of wooded grassland into cropland. Land conversion, in turn, may have fragmented wildlife habitat. Our objective was to assess the influence of the expansion of agricultural land‐use, brought about by tsetse control, on ecological properties by using bird species richness and composition as indicators of environmental impacts. We sampled bird species richness and composition (using Timed‐Species counts) and habitat structure (using field sampling and remote sensing) in four land cover/land‐use types in areas subjected to tsetse fly control and adjacent areas without control. At the height of the growing season bird species numbers and vegetative complexity were greater in the small‐holder, oxen‐plowed fields and riparian woodlands than in wooded grasslands or in large‐holder, tractor‐plowed fields. Species composition was highly dissimilar (40–70% dissimilarity) comparing among land‐use types, with many species found only in a single type. This implies that trypanosomiasis control that results in land conversion from wooded grasslands to small‐holder farming in this region may have no adverse impacts on bird species numbers but will alter composition. These results also suggest that moderate land‐use by humans (e.g., small‐holder field mosaics) increases habitat heterogeneity and bird species richness relative to high levels of use (e.g., tractor‐plowed fields). Tsetse control may be indirectly maintaining species richness in the valley by encouraging the differential spread of these small‐scale, heterogeneous farms in place of large‐scale, homogeneous farms. Nevertheless, if the extent of small‐holder farms significantly exceeds that of present levels, negative impacts on bird species richness and large shifts in species composition may occur.

Bird Populations in Shade and Sun Coffee Plantations in Central Guatemala - Russell Greenberg; Peter Bichier; Andrea Cruz Angon; Robert Reitsma (Conservation Biology, 1997)
We studied the avifauna of sun and shade coffee plantations and associated mid‐elevation habitats during the dry season of 1995. The three plantation types (Inga, Gliricidia, and sun) showed high faunistic similarities with each other and were both distinct and depauperate compared to matorral and forest patch habitats. Of all the coffee plantation habitats, Inga shade had the highest diversity. Species associated with wooded vegetation were more common in shade plantations, particularly in Inga. A second census showed a decline in bird numbers that was more pronounced in sun and Gliricidia than in Inga plantations. Overall, differences between the plantation types were small and all coffee plantations were less diverse than traditional coffee farms previously studied in nearby Chiapas, México. The relatively low bird diversity was probably due to the low stature, low tree species diversity, and heavy pruning of the canopy. These features reflect management practices that are common throughout Latin America. The most common species of birds in all coffee plantation habitats were common second‐growth or edge species; more specialized forest species were almost completely absent from plantations. Furthermore, many common matorral species were rare or absent from coffee plantations, even sun plantations with which matorral shares a similar superficial structure. Coffee plantations probably will only be important for avian diversity if a tall, taxonomically and structurally diverse canopy is maintained. We suggest this is most likely to occur on farms that are managed for a variety of products rather than those designated entirely for the production of coffee.

How to Creatively Fragment a Landscape - William F. Laurance; Claude Gascon (Conservation Biology, 1997)

Assessing Risks to Biodiversity from Future Landscape Change - Denis White; Priscilla G. Minotti; Mary J. Barczak; Jean C. Sifneos; Kathryn E. Freemark; Mary V. Santelmann; Carl F. Steinitz; A. Ross Kiester; Eric M. Preston (Conservation Biology, 1997)
We examined the impacts of possible future land development patterns on the biodiversity of a landscape. Our landscape data included a remote sensing derived map of the current habitat of the study area and six maps of future habitat distributions resulting from different land development scenarios. Our species data included lists of all bird, mammal, reptile, and amphibian species in the study area, their habitat associations, and area requirements for each. We estimated the area requirements using home ranges, sampled population densities, or genetic area requirements that incorporate dispersal distances. Our measures of biodiversity were species richness and habitat abundance. We calculated habitat abundance in two ways. First, we computed the total habitat area for each species in each landscape. Second, we calculated the number of habitat units for each species in each landscape by dividing the size of each habitat patch in the landscape by the area requirement and summing over all patches. Species richness was based on presence of habitat. Species became extinct in the landscape if they had no habitat area or no habitat units, respectively. We then computed ratios of habitat abundance in each future landscape to habitat abundance in the present for each species. We also computed the ratio of future to present species richness. We then calculated summary statistics across all species. Species richness changed little from present to future. There were distinctly greater risks to habitat abundance in landscapes that extrapolated from present trends or zoning patterns, however, as opposed to landscapes in which land development activities followed more constrained patterns. These results were stable when tested using Monte Carlo simulations and sensitivity tests on the area requirements. We conclude that this methodology can begin to discriminate the effects of potential changes in land development on vertebrate biodiversity.

A Habitat‐Based Metapopulation Model of the California Gnatcatcher - H. Reşi̇t Akçakaya; Jonathan L. Atwood (Conservation Biology, 1997)
We present an analysis of the metapopulation dynamics of the federally threatened coastal California Gnatcatcher (Polioptila c. californica) for an approximately 850 km 2 region of Orange County, California. We developed and validated a habitat suitability model for this species using data on topography, vegetation, and locations of gnatcatcher pair observations. Using this habitat model, we calculated the spatial structure of the metapopulation, including size and location of habitat patches and the distances among them. We used data based on field studies to estimate parameters such as survival, fecundity, dispersal, and catastrophes, and combined these parameters with the spatial structure to build a stage‐structured, stochastic, spatially‐explicit metapopulation model. The model predicted a fast decline and high risk of population extinction with most combinations of parameters. Results were most sensitive to density‐dependent effects, the probability of weather‐related catastrophes, adult survival, and adult fecundity. Based on data used in the model, the greatest difference in results was given when the simulation’s time horizon was only a few decades, suggesting that modeling based on longer or shorter time horizons may underestimate the effects of alternative management actions.

Why Environmental Policy Nightmares Recur - Steven L. Yaffee (Conservation Biology, 1997)
Many natural resource and environmental policy issues evidence recurring choices, made with considerable effort, whose temporary solutions never seem to deal with the underlying problems. Drawing on examples from endangered species policy, I describe five behavioral tendencies of humans and human institutions that result in recurrent environmental policy problems, including poor long‐term direction, delays, impasses, and piecemeal solutions to crosscutting problems. These tendencies are short‐term rationality outcompeting long‐term rationality, competitive behavior driving out cooperative behavior, fragmentation of interests and values, fragmentation of responsibilities and authorities, and fragmentation of information and knowledge. By understanding these tendencies, it is possible to frame policy solutions to them. This paper identifies a set of necessary responses including finding ways to bind current decisionmakers to the future, promoting creativity and risk‐taking on the part of public resource management organizations, utilizing alternative dispute resolution mechanisms that foster cooperation, building political concurrence, utilizing coordinating mechanisms, instituting clear performance measures, and implementing ways to promote information flows between organizations.

Subsistence Consumption of Coral Reef Fish Suggests Non‐Sustainable Extraction - Bruce E. Coblentz (Conservation Biology, 1997)

Predicting the Fates of Passeriform Introductions on Oceanic Islands - Michael P. Moulton; James G. Sanderson (Conservation Biology, 1997)

Who Cares About Life? - Philip Cafaro; Jerry A. Griffith; Paul Z. Goldstein; Bill Willers; John G. Sidle (Conservation Biology, 1997)

Hunting and the Likelihood of Extinction of Amazonian Mammals - Richard E. Bodmer; John F. Eisenberg; Kent H. Redford (Conservation Biology, 1997)
Species inhabiting tropical forests are thought to be on the verge of mass extinction. Much work has focused on extinction rates caused by deforestation; however, many of the recorded extinctions that have occurred since 1600 were a result of overhunting. We collected data on the relative abundance of large‐bodied mammals in the northeastern Peruvian Amazon in areas with persistent hunting pressure and in areas with infrequent hunting pressure. We quantified the effects of hunting by calculating the change in abundance of species between the infrequently and persistently hunted sites. We report that in Amazonian mammals weighing more than 1 kg the degree of population declines caused by hunting is correlated with the species’ intrinsic rate of natural increase (r max ), longevity, and generation time. Our results show that species with long‐lived individuals, low rates of increase, and long generation times are more vulnerable to extinction than species with short‐lived individuals, high rates of increase, and shorter generations.

Rule‐Based Models for Evaluating Mechanisms of Distributional Change - David K. Skelly; Eli Meir (Conservation Biology, 1997)
Viability models assume that particular mechanisms (e.g., decreased probability of colonization in isolated habitats) drive the pattern of population invasion and extinction. Although authors often provide evidence supporting the inclusion or exclusion of a mechanism, there has been no means of rigorously comparing different factors for a given species. We present a method of evaluating alternative mechanisms of distributional change that relies on two or more surveys of species presence‐absence across a large number of sites, a dataset often available (or at least attainable) for many taxa. The key idea of our approach is to use hypotheses to specify rules for dividing sites into classes. Our model estimates class‐specific probabilities of invasion and extinction and then uses these rates to assign invasions and extinctions to sites in multiple stochastic simulations. The output of the model is a frequency distribution of mistakes generated by comparing predicted distributions with the actual distributions. As a first attempt to apply the approach we modeled invasions and extinctions of 14 amphibian species across 32 ponds in Michigan. We compared hypotheses that amphibian distributions changed as a result of the spatial arrangement of sites, as a result of succession, or randomly. Overall, the spatial approach provided a poor explanation of distributional changes, performing no better than the random model for all species. In contrast, the succession model, based on temporal changes in breeding sites, performed better than the null model for at least three species. These results were surprising as spatial effects are thought to be important to the dynamics of pond‐breeding amphibians. Our results say little about the general importance of fragmentation and other spatial effects, but do suggest that alternative mechanisms of change can be important. Because of their ability to assess the importance of different mechanisms, rule‐based models could provide useful input into the design of biodiversity management strategies.

Ecological Status of Beaucarnea gracilis , an Endemic Species of the Semiarid Tehuacán Valley, México - Yuria Cardel; Victor Rico‐Gray; José G. García‐Franco; Leonard B. Thien (Conservation Biology, 1997)
We present a demographic analysis and suggestions for the conservation of Beaucarnea gracilis, a species endemic to the Tehuacán Valley, Puebla, México. The species is dioecious, it flowers every year, and the breeding system and floral display are typical of a generalist mode of pollination. The density of B. gracilis in the study plot was 16.7 individuals/ha. Distribution of trunk diameter size classes fits a normal distribution (n = 404), but the smaller sizes were not found (

The Effectiveness of Removing Predators to Protect Bird Populations - Isabelle M. Côté; William J. Sutherland (Conservation Biology, 1997)
The control of predators for nature conservation purposes is becoming an increasingly important issue. The growing populations of predator species in some areas and the introduction of predators in other areas have led to concerns about their impact on vulnerable bird species and to the implementation of predator control in some cases. This is set against a background of increasingly fragmented semi‐natural habitats and declining populations for many species. To assess the efficiency of predator removal as a conservation measure, the results of 20 published studies of predator removal programs were meta‐analyzed. Removing predators had a large, positive effect on hatching success of the target bird species, with removal areas showing higher hatching success, on average, than 75% of the control areas. Similarly, predator removal increased significantly post‐breeding population sizes (i.e. autumn densities) of the target bird species. The effect of predator removal on breeding population sizes was not significant, however, with studies differing widely in their reported effects. We conclude that predator removal often fulfills the goal of game management, which is to enhance harvestable post‐breeding populations, but that it is much less consistent in achieving the usual aim of conservation managers, which is to maintain and, where appropriate, increase bird breeding population sizes. This may be due to inherent characteristics of avian population regulation, but also to ineffective predator removal and inadequate subsequent monitoring of the prey populations.

What is Good Ecological Restoration? - Eric S. Higgs (Conservation Biology, 1997)
The rapid rise of ecological restoration is forcing consideration of what good restoration entails. Defining an end point for restoration is as much an ethical matter as a technical one, but scientifically trained restorationists have largely ignored the former issue. I argue that good restoration requires an expanded view that includes historical, social, cultural, political, aesthetic, and moral aspects. This expanded definition is necessary at a practical level to guide practitioners in the pursuit of excellence and at a conceptual level to prevent restoration from being swamped by technological activities and projects that veer away from ecological fidelity. Ecological fidelity is based on three principles: structural/compositional replication, functional success, and durability. These principles produce effective restoration, which is a necessary but not a sufficient condition of good restoration. An examination of characteristic problems that emanate from technological practices—reverse adaptation, an attention to product at the expense of process, and the separation of actions from consequences—leads directly to an expanded, inclusive framework for restoration. The results of an inclusive restoration process set up conditions necessary for restoration to achieve both ecological fidelity and harmonious human relationships within ecosystems.

Radiocollaring and Stress Hormones in African Wild Dogs - Scott Creel; Nancy Marusha Creel; Steven L. Monfort (Conservation Biology, 1997)

A natural "Benchmark" for Ecosystem Function - Yrjö Haila; Patrick J. Comer; Malcolm Hunter; Michael J. Samways; Clive Hambler; Martin R. Speight; Paul Hendricks; Stephen Herrero; F. Stephen Dobson; Andrew T. Smith; Jinping Yu (Conservation Biology, 1997)

Conservation and Civil Strife: Two Perspectives from Central Africa - Terese Hart; John Hart; Cheryl Fimbel; Robert Fimbel; William F. Laurance; Carrie Oren; Thomas T. Struhsaker; Howard C. Rosenbaum; Peter D. Walsh; Yvette Razafindrakoto; Michel Vely; Rob DeSalle (Conservation Biology, 1997)

Highly Differentiated Populations of the Narrow Endemic Plant Maguire Primrose ( Primula maguirei ) - Paul G. Wolf; Robert B. Sinclair (Conservation Biology, 1997)
Maguire primrose (Primula maguirei) is a geographically restricted plant species, known only from a 19‐km stretch of Logan Canyon in northern Utah (U.S.A.). We examined variation at 13 isozyme loci from 25 individuals of P. maguirei at each of eight sites. At individual loci we detected no statistically significant deviations from Hardy‐Weinberg proportions within sites (subpopulations). However, some loci were almost fixed for different alleles at the upper reaches of the species’ range relative to populations approximately 10 km away. The total mean gene diversity among loci was 0.22, of which 55% was partitioned within subpopulations, 0.7% among subpopulations within populations (100 m spatial scale), 3% among populations separated by about 1 km, and 41% between an Upper Canyon group of populations and a Lower Canyon group (10‐km scale). We detected no gametic disequilibria among loci within subpopulations (and populations). Two hypotheses are proposed to explain the results: (1) past genetic bottlenecks and (2) genetic divergence as a by‐product of local adaptations to different habitats. Regardless of the causes of allozymic differentiation, our results suggest that plans for artificial establishment or reestablishment of P. maguirei populations should use source populations within 1 km of the establishment site. This study emphasizes the potential use of data on population genetic structure for managing and monitoring rare species.

Ground Beetles as Indicators of Land Type Diversity in the Green Mountains of Vermont - Jessica J. Rykken; David E. Capen; Sean P. Mahabir (Conservation Biology, 1997)
Ground beetles (Coleoptera: Carabidae) captured in pitfall traps were compared within and among three Ecological Land Types in the Green Mountain National Forest, Vermont, to determine if beetle distributions can be linked to an ecological classification system designed to reflect biological diversity. Beetles were sampled in a nested‐scale design comprising three ecological land types, three polygons representing each ecological land type, five sites within each polygon, and six individual traps at each site. A nested analysis of variance showed only 2 of 35 species to vary significantly in relative abundance across ecological land types; most of the significant effects were at the site scale. To determine whether sites might sort into groups based on their beetle assemblages, sites were ordinated by detrended correspondence analysis and classified by two‐way indicator species analysis. Ordinations suggested that the distribution of ground beetles was somewhat influenced by site moisture; classification separated groups of hygrophilous species and wet sites from other ecologically uninterpretable species assemblages and site‐groups. Several of the site‐groups contained sites affiliated primarily with one ecological land type. However, a nested analysis of variance using the relative abundance of each of the species assemblages again showed most significant effects to be at the site scale. Results indicated that ground beetle distributions were not significantly linked with ecological land types and that the ground beetle fauna of the mid‐elevation forests of the western Green Mountains is comprised mainly of forest generalists, with some specialist species responding to a moisture gradient at the site scale. Because the ecological land type units did not explain distributions of carabids, these organisms should next be related to higher and lower scales within the classification system. Distributions of other invertebrate and vertebrate species should also be studied to test the utility of this ecological classification system for monitoring forest biodiversity.

Mitochondrial DNA Variability and Conservation Genetics of the Sumatran Rhinoceros - Juan Carlos Morales; Patrick Mahedi Andau; Jatna Supriatna; Zainal‐Zahari Zainuddin; Don J. Melnick (Conservation Biology, 1997)

Allozyme Variation in Ophiopogon xylorrhizus , an Extreme Endemic Species of Yunnan, China - Song Ge; Da‐Ming Zhang; Hai‐Qun Wang; Guang‐Yuan Rao (Conservation Biology, 1997)

Behavioral Considerations in Fragmented Landscapes - Richard H. Yahner; Carolyn G. Mahan (Conservation Biology, 1997)

Effects of Livestock Grazing on Stand Dynamics and Soils in Upland Forests of the Interior West - A. Joy Belsky; Dana M. Blumenthal (Conservation Biology, 1997)
Many ponderosa pine and mixed‐conifer forests of the western, interior United States have undergone substantial structural and compositional changes since settlement of the West by Euro‐Americans. Historically, these forests consisted of widely spaced, fire‐tolerant trees underlain by dense grass swards. Over the last 100 years they have developed into dense stands consisting of more fire‐sensitive and disease‐susceptible species. These changes, sometimes referred to as a decline in “forest health,” have been attributed primarily to two factors: active suppression of low‐intensity fires (which formerly reduced tree recruitment, especially of fire‐sensitive, shade‐tolerant species), and selective logging of larger, more fire‐tolerant trees. A third factor, livestock grazing, is seldom discussed, although it may be as important as the other two factors. Livestock alter forest dynamics by (1) reducing the biomass and density of understory grasses and sedges, which otherwise outcompete conifer seedlings and prevent dense tree recruitment, and (2) reducing the abundance of fine fuels, which formerly carried low‐intensity fires through forests. Grazing by domestic livestock has thereby contributed to increasingly dense western forests and to changes in tree species composition. In addition, exclosure studies have shown that livestock alter ecosystem processes by reducing the cover of herbaceous plants and litter, disturbing and compacting soils, reducing water infiltration rates, and increasing soil erosion.

Macroinvertebrate Colonization of Woody Debris in Canadian Shield Lakes following Riparian Clearcutting - R.L. France (Conservation Biology, 1997)
Deployment of litterfall traps revealed that clearcut logging of boreal riparian forests in northwestern Ontario, Canada resulted in a dramatic shift from once dominant conifers to regrowth composed largely of deciduous trees and reduced the allochthonous inputs of small woody debris to lake littoral zones by over 90%. Due to the rarity of macrophytes in these oligotrophic lakes, littoral macroinvertebrates were found to actively colonize woody debris placed within mesh litter bags. The recalcitrant nature of small woody debris in these lakes (average median persistence time of about 5 years estimated from mass loss data) indicates, however, that this important habitat resource will probably never completely disappear in relation to its projected rate of resupply during post‐disturbance forest regeneration. Colonization rates of twigs and bark contained within the litter bags were not found to differ between coniferous and deciduous species. This indicates that macroinvertebrates in these boreal lakes are merely opportunistic colonizers of woody debris, probably for its use as either a biofilm substrate or a predation refuge. As a result, shifts in tree species composition following riparian clearcutting should not detrimentally affect the taxa richness or organism abundance of aquatic macroinvertebrates in these lakes.

Regional Biodiversity Planning and Lemur Conservation with GIS in Western Madagascar - A. P. Smith; N. Horning; D. Moore (Conservation Biology, 1997)
Primary forest cover in western Madagascar declined from 12.5% in 1950 to 2.8% in 1990. Approximately 23% of remaining forest is located within reserves, but this is no guarantee of protection. Forest cover in the Andranomena Reserve in western Madagascar has been reduced by 44% since 1950. The identification of priority areas for establishment of development projects has been constrained by lack of information on the distribution, abundance, and habitat requirements of threatened species and the size, condition, and threats to survival of forest remnants. We evaluate a rapid fauna survey and habitat modeling procedure specifically designed to generate information for reserve selection and design using Geographical Information Systems (GIS). The study was conducted in the largest remnant (94,000 ha) of primary monsoon rainforest in western Madagascar, using lemurs as an indicator group. Lemur abundance and microhabitat variables were measured at 64 stratified survey sites dispersed throughout the region. These records were incorporated into a GIS with other environmental and landuse data derived from maps and satellite imagery. Statistical procedures were applied to analyze species habitats, predict and map species distributions, and estimate species population sizes throughout the study area. Patterns of slash and burn agriculture and anthropogenic disturbance were also analyzed to identify areas at low risk of cultural disturbance. A map of disturbance risk was overlaid with a map of relative lemur biodiversity to identify conservation priority areas with high biodiversity and low risk of short term disturbance. Lemur diversity was most strongly influenced by habitat clearing and human disturbance (harvesting, stock grazing, and hunting) within 8 km of villages. Lemur diversity was highest in a region of higher elevation and rainfall, distant from villages and roads. The only existing reserve in the study area was located in a region of high disturbance risk. Almost half the reserve has been degraded during the past 45 years. There is considerable scope for re‐allocation of land use within the study area to include a core protected area, a buffer zone with controlled hunting and timber harvesting, and an adjacent ecotourism facility. We found that information generated by a stratified biodiversity and landuse survey at a sampling intensity of less than 0.1% was sufficient to provide an objective foundation for regional biodiversity planning.

Genetic Diversity in the Endangered Lily Harperocallis flava and a Close Relative, Tofieldia racemosa - Mary Jo W. Godt; Joan Walker; J. L. Hamrick (Conservation Biology, 1997)
We examined genetic diversity in 464 individuals of the monotypic lily Harperocallis flava in its two habitats (seepage bogs and a roadside right‐of‐way) and five populations of a co‐occurring related lily, Tofieldia racemosa. The endangered H. flava, endemic to the Apalachicola lowlands of the Florida panhandle, was monomorphic for the 22 loci scored. In contrast, T. racemosa had a high proportion of polymorphic loci ( P s = 68.2%; P p = 47.7%) with moderate genetic diversity ( H es = 0.134; H ep = 0.114). Estimated gene flow was moderately high ( Nm = 2.07) for T. racemosa, with most (93%) of the total genetic diversity found within populations. Despite the low level of genetic divergence, some isolation by distance was detected among T. racemosa populations. Harperocallis flava and other species without discernable genetic variation pose special problems for conservation biologists because genetic criteria are not available for the development of ex situ and in situ conservation and management strategies.

Population Viability Analysis of the Florida Manatee ( Trichechus manatus latirostris ), 1976–1991 - Miriam Marmontel; Stephen R. Humphrey; Thomas J. O'Shea (Conservation Biology, 1997)
Recent development of age‐determination techniques for Florida manatees (Trichechus manatus latirostris) has permitted derivation of age‐specific data on reproduction and survival of a sample of 1212 carcasses obtained throughout Florida from 1976–1991. Population viability analysis using these data projects a slightly negative growth rate (−0.003) and an unacceptably low probability of persistence (0.44) over 1000 years. The main factors affecting population projections were adult survival and fecundity. A 10% increase in adult mortality would drive the population to extinction over a 1000‐year time scale, whereas a 10% decrease in adult mortality would allow slow population growth. A 10% decrease in reproduction would also result in extinction. We conclude that management must focus on retaining and improving the conditions under which manatee demography operates. The major identified agent of mortality is boat‐manatee collisions, and rapidly increasing numbers of humans and registered boats portend an increase in manatee mortality. Zoning of manatee‐occupied waters for reductions in boating activity and speed is essential to safeguard the manatee population. If boating regulations being implemented by the state of Florida in each of 13 key coastal counties are completed, enforced, and effective, manatees and human recreation could coexist indefinitely. If regulation is unsuccessful, the Florida manatee population is likely to decline slowly toward extinction.

How Many Things Are There? A Reply to Oliver and Beattie, Beattie and Oliver, Oliver and Beattie, and Oliver and Beattie - Paul Z. Goldstein (Conservation Biology, 1997)

Enterococcal numbers measured in waters of marine, lake, and river swimming sites of the Bay of Plenty, New Zealand - Joanne Deely; Sean Hodges; John McIntosh; David Bassett (New Zealand Journal of Marine and Freshwater Research, 1997)
In the Bay of Plenty, New Zealand, 32 coastal beach sites, 23 lake beach sites, and 31 river swimming hole sites were sampled for enterococci as indicators of bathing suitability over 3 summers (from 1991 to 1995). The median enterococcal numbers of 5 samples collected from each site over each season were compared to the guideline medians: 35 and 33 enterococci per 100 ml for marine and fresh waters, respectively. The “5‐sample median” values generally agreed with longer‐term medians (n = 24, 28) from river and estuary sites sampled between 1990 and 1994. During the summers of 1991 and 1993, high enterococcal numbers at marine and lake swimming sites were assumed to be derived primarily from sewage effluent and farm run‐off, either directly or from freshwater inflows. Enterococcal numbers dropped significantly in these waters when effluents were either treated or removed from the waters. In 1995, all marine bathing waters complied with the guideline value of 35 enterococci per 100 ml. Evidence from long‐term monitoring of estuary sites indicated that most marine bathing sites have high‐quality bathing water with short‐term variability caused by winds, tides, and outfall discharges. In 1995, all but one lake site complied with the freshwater median guideline of 33 enterococci per 100 ml. Most upstream river sites also complied with the freshwater guideline. However, river sites in the mid reaches and down stream recorded high enterococcal numbers which increased slightly at some sites from 1992 to 1995. The most significant increase in bacterial numbers was recorded in the small river and stream swimming holes which carry low volumes of water ( −1 ), particularly in the western area of Lake Rotorua. The main source of enterococci in river waters was most likely run‐off from dairy farms on the flood plains of the various rivers of the Bay of Plenty.

Coolia monotis (Dinophyceae): A toxic epiphytic microalgal species found in New Zealand (Note) - Lesley L. Rhodes; Annabel E. Thomas (New Zealand Journal of Marine and Freshwater Research, 1997)
Coolia monotis Meunier (Dinophyceae) was isolated from drift seaweed collected from Ninety Mile Beach, Northland, New Zealand. It is a new record for New Zealand waters. The microalga was identified by scanning electron microscopy and cultured in a seawater‐based medium. Cultures grew preferentially at 25°C (subtropical temperatures), rather than at 20°C (temperate), and at salinities >28. Coolia monotis proved to be toxic to larvae of Artemia salina and Haliotis virginea .

Direct estimation of natural mortality of the New Zealand abalone, Haliotis iris (Note) - Paul E. McShane; J. Reyn Naylor (New Zealand Journal of Marine and Freshwater Research, 1997)
Rates of natural mortality (M) of Haliotis iris were estimated by monitoring enclosed populations, and from the frequency of empty marked shells recovered from natural populations. Annual instantaneous rates were ≤ 0.1 in all instances. The major source of mortality was predation by the starfish Astrostole scabra . Predation by fishes was evidently low. The low rates of natural mortality suggest that fisheries for H . iris may be less productive than those of other species of abalone.

Mortality and tag loss in dart and loop‐tagged captive snapper, Pagrus auratus (Sparidae), with comparisons to relative recapture rates from a field study - David McGlennon; Deborah Partington (New Zealand Journal of Marine and Freshwater Research, 1997)
Tag shedding rates of Hallprint dart and loop tags, and tag‐related mortality in the snapper Pagrus auratus were experimentally determined on fish held in captivity for periods up to 18 months. An artefact of the experimental process appeared to exacerbate dart tag shedding in one treatment. However, for other treatments, the instantaneous shedding rates for the first 7 months was 0.0006 day −1 . Shedding rates were not linear for periods beyond 7 months and were described by a logistic function. The instantaneous shedding rate for the loop tags was much lower at 0.00016 day −1 . Overall mortality during the experiment was only 1.9% and the causes of death could not be related to tagging. The relative return rates of the two different tag‐types from a field tagging programme were compared after analysis of fish size, spatial, temporal, and tagger‐type distribution. In all direct comparisons within each stratum, loop tag return rates were higher. It was concluded that the retention capabilities are better for loop tags than for dart tags in P. auratus .

Comparing past and present trophic states of seven Central Volcanic Plateau lakes, New Zealand - N. M. Burns; J. Deely; J. Hall; K. Safi (New Zealand Journal of Marine and Freshwater Research, 1997)
Data on seven lakes in the Rotorua District were examined to determine trophic state changes in these lakes. The method of data analysis was specifically designed to find small changes in the trophic state of lakes. For each variable, the P‐ value from 12 monthly paired sample Student t‐ test comparisons was calculated and a change of trophic state value (CTS) was assigned, based on the P‐value. The CTS values for all the variables examined for a single lake were averaged (C) with a standard error (CV). The resulting Change/ Confidence Value index (C/CV) indicated the nature of the trophic change observed and the degree of confidence that could be placed in the stated change. This study finds that in recent years Lakes Rotorua and Rotoiti have become less eutrophic; Lakes Okareka and Rotoma may have become less eutrophic; Lakes Okataina and Rotokakahi have not changed in trophic state in the last 22 years, and Lake Tikitapu may have become more eutrophic.

Uses and effects of cultured fishes in aquatic ecosystems, edited by H. L.SchrammJr and R. G.Piper1995. AFS Symposium 15, 608 p. ISBN 0–913235–91–1. Available from American Fisheries Society, 5410 Grosvenor Lane, Suite 110, Bethesda, Maryland 20814–2199, USA. Price: US$51.Seaweeds of New Zealand, an illustrated guide, by Nancy M.Adams, 1994. Canterbury University Press, Christchurch, New Zealand. 360 p. Price: $79.95 (incl GST). ISBN 0–908812–21–3. - Nigel McCarter; Murray J. Parsons (New Zealand Journal of Marine and Freshwater Research, 1997)

Spatial and temporal variation in the growth rate of elephantfish (Callorhinchus milii) - Malcolm P. Francis (New Zealand Journal of Marine and Freshwater Research, 1997)
Growth rate estimates were obtained for elephantfish using length‐frequency and tag‐recapture data from the east coast of South Island during 1966–88. Elephantfish hatch from egg cases at about 10 cm fork length (FL) during May‐July. Females grow faster than males after their first year and growth is fastest in summer. In 1966–68, elephantfish in Pegasus Bay grew faster than in Canterbury Bight, resulting in modal length differences that were maintained for the first 3 years of life. This suggests there are at least two distinct juvenile nurseries. Maximum observed lengths were 76 cm FL for males and 97 cm FL for females. Length‐frequency analyses identified 5–8 male age classes and 8–9 female age classes, but longevity probably exceeds these values. Growth rates of 0+ elephantfish in Pegasus Bay in 1983—84 and Canterbury Bight in 1988 were 33–56% greater than in 1966–68. The faster growth rate meant male age at maturity was 4+ in the 1960s and 2+ to 3+ in the 1980s. If female length at maturity was the same in the 1980s as in the 1960s, then female age at maturity would have been 5+ to 6+ in the 1960s and 4+ to 5+ in the 1980s. The increased growth rates and earlier maturity may have led to an increase in elephantfish stock productivity between the 1960s and 1980s.

Photosynthetic parameters in water masses in the vicinity of the Chatham rise, south pacific ocean, during late summer - Ian Hawes; Mark Gall; Mark Weatherhead (New Zealand Journal of Marine and Freshwater Research, 1997)
The relationship between photosynthesis (P) and light (E) was determined for phytoplankton from the mixed layer and the deep chlorophyll maximum (DCM) at 23 stations off the east coast of New Zealand during February‐March 1995. The stations encompassed three water masses, Sub‐tropical, Sub‐antarctic and the Sub‐tropical Convergence Zone. The light‐saturated rate of photosynthesis (P max ) and slope of the light‐limited portion of the curve (a) were determined using a light gradient incubator. The absorption spectra of the phytoplankton assemblages were used to calculate the maximum quantum efficiency of photosynthesis (ϕ max )‐ A higher mixed‐layer P max in Sub‐tropical water over Sub‐antarctic water (4.26 compared to 5.85 mg C (mg Chl.a) −1 h −1 ) was consistent with the temperature difference of 4°C, although there was also a taxonomic composition difference between these waters. The highest variability of P max and α, as well as the highest P max values, were seen within the STC, but ranges for all water masses overlapped. Physical conditions in the water masses were similar and no correlations between any measured physical or chemical feature of the stations and any P‐E parameter could be identified.

Avoidance of suspended sediment by the juvenile migratory stage of six New Zealand native fish species - Jacques A. T. Boubée; Tracie L. Dean; David W. West; Rhys F. G. Barrier (New Zealand Journal of Marine and Freshwater Research, 1997)
The avoidance response of the migratory juvenile stage of six species of diadromous fish to different levels of suspended solid (SS) was determined in the laboratory using a two‐choice avoidance tank. Trials were mostly conducted with resuspended sediment from the outlet of Lake Waahi, New Zealand, but a series of tests was also conducted with kaolin for comparison. Banded kokopu (Galaxias fasciatus) was the most sensitive species, displaying a 50% avoidance response to kaolin and Waahi silt at 17 and 25 NTU, respectively. Koaro (Galaxias brevipinnis) and inanga (Galaxias maculatus) were found to be less sensitive than banded kokopu, with a 50% avoidance response to Waahi silt at 70 and 420 NTU, respectively. Shortfinned and longfinned elvers (Anguilla australis and/1, dieffenbachii) , and redfinned bullies (Gobiomorphus huttoni) showed no avoidance behaviour, even at the highest turbidities (1100 NTU) tested. Based on these laboratory results, and until field testing is undertaken, a limit of about 15 NTU in otherwise clear waterways should ensure that the upstream migration of some of the most common New Zealand native freshwater species will not be affected.

Mitigation of Habitat “Take”: Application to Habitat Conservation Planning - Bruce B. Bingham; Barry R. Noon (Conservation Biology, 1997)
One of the most important provisions of the U.S. Endangered Species Act precludes the “taking” of listed species on both public and private land. In past Endangered Species Act litigation, take has been broadly interpreted to include the destruction or modification of habitats as well as the direct killing of animals. This requirement created an extensive burden on private landowners to provide habitats for listed species. This burden was substantially lessened when the ESA was modified in 1982 to allow incidental takings conditioned on preparation of a satisfactory “habitat conservation plan.” Because the majority of listed species are imperiled due to habitat modification, most habitat conservation plans must demonstrate defensible methods to mitigate against incidental habitat loss. A review of HCPs for the Northern Spotted Owl ( Strix occidentalis), and other species, indicates that mitigation solutions are often arbitrary, lacking an empirical foundation in the species’ life history requirements. Based on data from the Spotted Owl, we illustrate a biologically based method for estimating the areal requirements necessary to mitigate against the take of essential habitats. Toward this goal we adopt the concept of “core area,” that portion of an animal’s home range that receives disproportionate use. We estimated core areas by means of the adaptive kernel density function and tested against a null distribution of animal use that assumes a bivariate, uniform distribution of locations within the home range. The method we illustrate, which is defensible, repeatable, and empirical, is a clear improvement over the ad hoc methods used in many habitat conservation plans. Further, the methods we propose should be applicable to a large number of terrestrial species for which home range is a meaningful concept.

Biologically Significant Population Declines and Statistical Power - J. Michael Reed; Andrew R. Blaustein (Conservation Biology, 1997)

Reproductive Success of Worm‐Eating Warblers in a Forested Landscape - George A. Gale; Lise A. Hanners; Stephen R. Patton (Conservation Biology, 1997)

Balancing the Books on Biodiversity - Douglas W. Morris; Lawrence Heidinga (Conservation Biology, 1997)

Population Constraints Associated with the Use of Black Rhinos as an Umbrella Species for Desert Herbivores - Joel Berger (Conservation Biology, 1997)
The numerous tactics used to conserve biodiversity include the designation of protected areas, political change, and research and education, the latter involving paradigms such as insular biogeography and the “umbrella species concept.” In Namibia lands removed from national park status in 1970 and currently under the jurisdiction of indigenous people now contain one of the few unfenced populations of black rhinos (Diceros bicornis) remaining in Africa. Theory predicts that the protection of umbrella species will ensure the survival of other biota that require(s) less space. To gauge how well biodiversity might be retained by examining the spatial needs of a small population of black rhinos, I used data gathered under various ecological conditions to estimate mean and minimum population sizes of six large herbivores of the Namib Desert ranging in size from giraffe (Giraffa camelopardalis) to springbok (Antidorcas marsupialis) and ostrich (Struthio camelus). My results indicate that annual differences in rainfall, both within and between seasons, resulted in wide fluctuations in herbivore population sizes for all species except rhino. Although other herbivores switched to areas of higher rainfall, rhinos did not. The data suggest that under conditions of extreme environmental variance the space used by rhinos alone was unlikely to assure the existence of populations of other species in excess of 250 individuals. Fifty percent of the species failed to exceed 150 individuals 50% of the time and one third of the species never attained populations in excess of 50 individuals. However, by employing assumptions about the spatial needs of rhino populations numbering up to 100 individuals, the mean minimum population sizes attained by any of four desert herbivores is 535. A future challenge in using rhinos and other large‐bodied species as umbrellas for organisms of either similar or dissimilar trophic levels will be the refinement of estimates of population viability.

Paleontological and Cultural Perspectives on Livestock Grazing in Southwestern Rangelands: Response to Brown and McDonald - Joseph P. Dudley (Conservation Biology, 1997)

Minimal Genetic Variation in a Coastal Dune Arthropod: The Trapdoor Spider Aptostichus simus ( Cyrtaucheniidae ) - Martin G. Ramirez; Julie L. Froehlig (Conservation Biology, 1997)

Acceptance of Scientific Management by Natural Resource Dependent Communities - Priscilla Weeks; Jane M. Packard (Conservation Biology, 1997)
We explore the reaction of two resource dependent communities, west Texas ranchers and Gulf Coast oyster fishers, to scientific resource management. We examine the criteria these two social groups use to judge scientific claims, and by extension, scientific resource management. Although scientists rely on factors internal to the scientific enterprise (e.g., methodological rigor), natural resource dependent communities such as ranchers and fishers may rely on factors external to the scientific process. Such factors include the historical relationship the community has had with the managing agency, the extent to which scientific explanations match local experience, the conceptual fit between managers’ and communities’ views of the appropriate relationship between humans and nature, and the resources available to the community to argue against regulation. We conclude that (1) agencies should explore the possibility of including the experiential knowledge of natural resource users where applicable and (2) agencies should recognize that communication skills can be as important as scientific skills in reaching management goals.

Prioritizing Pacific Salmon Stocks for Conservation - Fred W. Allendorf; David Bayles; Daniel L. Bottom; Kenneth P. Currens; Christopher A. Frissell; David Hankin; James A. Lichatowich; Willa Nehlsen; Patrick C. Trotter; Thomas H. Williams (Conservation Biology, 1997)
Over 300 native stocks of Pacific salmon, steelhead, and coastal cutthroat trout (Oncorhynchus spp.) are at risk of extinction in the Pacific Northwest. With only limited resources available for conservation and recovery, prioritization of these stocks may become necessary if meaningful measures are to be implemented. We propose criteria by which prioritization may be guided. First, we rank stocks for risk of extinction, either by population viability analysis or by a set of surrogate measures. Then we rank stocks for biological consequences of extinction, using sets of questions designed to establish the genetic and evolutionary consequences and the ecological consequences if a stock were to become extinct. Together, these rankings allow stocks to be prioritized for a range of possible actions, with those stocks at highest risk and bearing the greatest biological consequences of extinction receiving attention first. Application of the prioritization process to 20 Pacific anadromous salmonid stocks worked as intended, although data limitations are considerable. The process is most likely to work successfully when applied to many stocks on which data exist, when several experts carry out the prioritization, and when the results are peer reviewed.

The Missing Awareness, Part 2: Teaching Students What a Billion People Looks Like - John B. Dunning (Conservation Biology, 1997)

Genetic Introgression of Endemic Taxa by Non‐natives: A Case Study with Leon Springs Pupfish and Sheepshead Minnow - Anthony A. Echelle; Alice F. Echelle (Conservation Biology, 1997)
Genetic studies of a pupfish (Cyprinodon bovinus) endemic to a small, spring‐fed system in west Texas illustrate the potential for small introductions of non‐native species to cause large‐scale genetic changes through hybridization and genetic introgression. We performed a genetic survey (allozymes and RFLP analysis of mtDNA) of four samples of C. bovinus representing all wild populations of the species and a captive population maintained since 1976 at Dexter, New Mexico. The results indicate genetic introgression of the entire wild population by sheepshead minnow (C. variegatus), a coastal species with a history of introductions in west Texas. Frequencies of foreign genetic elements averaged across four diagnostic allozyme loci and mtDNA varied from 6.1 to 15.1%. The captive population appears free of foreign genetic material. Comparisons with past studies of C. bovinus indicate the present situation is largely due to a recent introduction of C. variegatus, not to an introduction in the mid‐1970s; however, residual effects from the earlier introduction cannot be completely discounted. Genetic analysis indicates that the source of introduced C. variegatus in Diamond Y Draw is the nearest known population, an introduced stock in Lake Balmorhea approximately 90 km away. The results demonstrate the value of maintaining imperiled species in captivity. Captive C. bovinus provide an opportunity to restore the genetic integrity of wild populations.

Extinction Debts and Risks Faced by Abundant Species - Michael A. McCarthy; David B. Lindenmayer; Martin Drechsler (Conservation Biology, 1997)
A recent model indicating that good competitiors and abundant species face the greatest risk of extinction from habitat destruction is critically examined. The conclusions drawn from the model are shown to rely on a number of assumptions regarding the mechanism of species coexistence, the relationship between abundance and competitive ability, and spatial characteristics of habitat destruction. The generality of these assumptions is questioned. Of particular concern are the assumptions that good competitors are poor dispersers, and that good competitors are the most abundant species. Furthermore, we suggest that the spatial scale of metapopulation dynamics in the model may not be appropriate for representing impacts of habitat destrustion. Empirical evidence is discussed indicating the limited applicability of the model for describing effects of habitat destruction on risks of species extinctions. Examples from a number of fragmented systems demonstrate that poor competitors and rare species are vulnerable to habitat destruction.

Conservation Implications of Genetic Differentiation in Southern African Populations of Black Rhinoceros ( Diceros bicornis ) - M. K. J. Swart; J. W. H. Ferguson (Conservation Biology, 1997)
We analyzed 30 protein‐coding loci of four southern African black rhinoceros populations in order to calculate fixation indices and genetic distances for the different populations. We concluded that one of these populations is of the subspecies Diceros bicornis bicornis and the other three of Diceros bicornis minor. No evidence of inbreeding within populations was found. F‐ statistics revealed significant differentiation between populations. Small genetic distances found among the four populations reveal that they are conspecific, and no evidence was found to support the claim that the populations belong to discrete subspecies. Rather, an east‐west cline in genetic characteristics appears to exist with G6pd and HB‐2 alleles peculiar to western populations and Es‐2 and GP‐3 alleles peculiar to eastern populations.

Reflections on “What is Ecosystem Management?” - R. Edward Grumbine (Conservation Biology, 1997)
I review 10 dominant themes of ecosystem management described in the paper “What is Ecosystem Management?” (Grumbine 1994a) based on feedback received from managers actively implementing ecosystem management projects in the field. My emphasis is on practical advice from working professionals for working professionals. Key points include the importance of managing for ecological integrity, the need for social as well as scientific data, suggestions for implementing cooperation strategies and conservation partnerships, a pragmatic definition of adaptive management, and first steps toward changing the structure of natural resource organizations. As ecosystem management evolves, the pressure for change within traditional resource management agencies appears to be reaching a critical point.

Ecological Sustainability as a Conservation Concept - J. Baird Callicott; Karen Mumford (Conservation Biology, 1997)
Neither the classic resource management concept of maximum sustainable yield nor the concept of sustainable development are useful to contemporary, nonanthropocentric, ecologically informed conservation biology. As an alternative, we advance an ecological definition of sustainability that is in better accord with biological conservation: meeting human needs without compromising the health of ecosystems. In addition to familiar benefit‐cost constraints on human economic activity, we urge adding ecologic constraints. Projects are not choice‐worthy if they compromise the health of the ecosystems in which human economic systems are embedded. Sustainability, so defined, is proffered as an approach to conservation that would complement wildlands preservation for ecological integrity, not substitute for wildlands preservation.

Historical and Cultural Perspectives on Grazing: Reply to Dudley - James H. Brown; William McDonald (Conservation Biology, 1997)

Changes in Distribution and Abundance of the Loggerhead Shrike - Tom J. Cade; Christopher P. Woods (Conservation Biology, 1997)
The Loggerhead Shrike (Lanius ludovicianus) was once widely distributed and common over most of North America, occupying an exclusive breeding range with no other shrikes. Although it occurs in a wide variety of plant associations, this shrike is generally found in landscapes characterized by widely spaced shrubs and low trees interspersed with short grasses, forbs, and bare ground, habitats which include deserts, scrub lands, savannas, and some agricultural settings. The Loggerhead Shrike seems to have been always most abundant in the southern and western portions of its range, with high breeding densities from Florida across the gulf states to Texas and throughout the arid regions of the West. A northeastward expansion in range occurred in the late 1800s in association with deforestation and agriculture. A similar north central expansion occurred in the 1900s with agricultural development of the northern Great Plains and aspen parklands. Contraction and decrease in numbers have been noted in parts of its range since the 1940s, concurrent with the regrowth of forests, loss of pasturelands, and intensive row‐crop agriculture. More recently, Christmas Bird Count data and Breeding Bird Survey data have revealed an overall downward trend across the continent at least since 1966, although numbers are stable or increasing in some locations. Field studies generally implicate alterations in habitat structure and loss of habitat as factors responsible for changes in breeding distribution and overall abundance. Nevertheless, considering its entire distribution in North America and its historical expansions and contractions of range associated with habitat changes, the Loggerhead Shrike does not appear threatened with extinction as a species. We favor a hands‐on approach to management of the critically endangered subspecies, L. l. mearnsi and L. l. migrans, however, and recommend extensive preservation of the natural scrub desert, shrub‐steppe, western oak savanna, and southern savanna vegetation types, which appear to be optimal, core habitats for this species, as well as fostering land‐use practices that favor shrikes in agricultural and suburban landscapes.

Cytochrome b Sequences from the Endangered Saudi Gazelle ( Gazella Saudiya ) Suggest Hybridization with Chinkara ( G. bennetti ) - W. E. R. Rebholz; E. H. Harley (Conservation Biology, 1997)

Conservation Implications of Patterns of Horn Regeneration in Dehorned White Rhinos - Janet L. Rachlow; Joel Berger (Conservation Biology, 1997)
The demand for rhino horn has led to drastic declines in numbers of rhinos in Asia and Africa. Although all trade in rhino products has been illegal since the mid‐1970s, a lucrative illegal market flourishes and poaching continues. Horn removal from African rhinos has been conducted in Zimbabwe, Namibia, and Swaziland to deter poaching. Regeneration of horns following dehorning has created the potential for a sustainable harvest of rhino horn through dehorning programs. Establishment of a regulated legal market for rhino horn has been suggested to help fund rhino conservation programs in African countries. However, evaluation of an economic harvest of rhino horn from dehorning programs has been limited because few data on rates and form of horn regeneration exist. Because rate of horn regeneration will determine the interval at which rhino horns could be harvested profitably, we measured horn regrowth for two white rhino (Ceratotherium simum) populations studied in Zimbabwe between 1991–1995. Measurements of horn sizes were collected before and after dehorning, and mass to volume relationships were calculated. Von Bertalanffy growth curves were used to model horn size and rates of horn regrowth relative to age. Adult males had larger horn bases (p 1.3 kg/yr) was almost twice the mass of adult females. Based on an economic model for profit maximization, intervals for dehorning range from 1.16 to 1.51 years and vary with both sex and age. We suggest managers use these values as minimum dehorning intervals to balance profits with longer‐term management goals. Rates of horn regeneration are likely to be less important than law enforcement in determining the efficacy of dehorning as a deterrent to rhino poaching.

Hotspots of Epiphytic Lichen Diversity in Two Young Managed Forests - Peter N. Neitlich; Bruce McCune (Conservation Biology, 1997)
Understanding within‐stand variation in diversity of epiphytes will provide an improved basis for producing timber while conserving biological diversity. Two 80‐ha, 50–year–old managed stands of conifers were surveyed to locate 0.4 ha putative “diversity” plots, the areas appearing most diverse in lichen epiphytes. These plots were generally located in areas made heterogeneous by canopy gaps, wolf trees (trees with large‐diameter lower branches), and old‐growth remnant trees. “Matrix” plots, in contrast, were chosen at random from the remaining, more homogenous forest. Diversity plots hosted from 25% to 40% more epiphytic lichen species than matrix plots in both stands. The strongest within‐stand gradients in species composition were correlated with percentage of plot occupied by gaps and wolf trees. Percentage of the plot in gaps was correlated with species richness (r = 0.79). In the more structurally diverse stand, diversity and abundance of nitrogen‐fixing “cyanolichens” were correlated with percentage of the plot occupied by gaps (0.5

The Pollyannas vs. the Chicken Littles— Enough Already! - Hal Salwasser; Douglas W. MacCleery; Thomas A. Snellgrove (Conservation Biology, 1997)

History and Importance of Land Use and Protection in the North Quabbin Region of Massachusetts (USA) - Alisa D. Golodetz; David R. Foster (Conservation Biology, 1997)
Evaluating the consequences and future of land protection requires broad temporal and spatial perspectives of ecological and cultural factors. We assessed the development of a system of protected areas comprising 37% of central Massachusetts in terms of changing rates and means of land protection. We compared protected areas to the surrounding matrix in terms of physical, biological, and historical features and used these results to raise issues concerning future planning. The rate, purpose, and means of land protection in the North Quabbin Region (168,312 ha) have been dynamic as a result of changes in cultural values and transformation of the landscape from predominantly agriculture to forest. Protected lands are managed by 25 federal and state agencies, private groups, and municipal departments and commissions and are physically and biologically typical of the regional landscape which results from (1) participation of diverse organizations with varied agendas; (2) predominance of large government acquisitions driven by landscape‐scale criteria; and (3) absence of coordination among groups. The large area, relative homogeneity and largely undeveloped status of the North Quabbin Region suggest conservation goals distinct from those in the fragmented and extensively developed neighboring areas of the Connecticut River Valley and Cape Cod and Islands Region. Large tracts of forests, wetlands, and lakes in the North Quabbin Region provide (1) habitat for species requiring extensive, intact areas; (2) the opportunity to maintain broad‐scale ecological processes; (3) connections to regional conservation areas; and (4) recreation. To realize the area’s potential, a comprehensive plan must be based on a broad‐scale perspective and historical understanding of the landscape.

Predicting Invasions of Woody Plants Introduced into North America - Sarah Hayden Reichard; Clement W. Hamilton (Conservation Biology, 1997)
Plant species continue to be introduced in North America for various purposes. If the trend continues, it is probable that some will escape cultivation and become invasive in native ecosystems. We present a retrospective analysis of several structural, life history, and biogeographical attributes of woody plants introduced in North America to determine which traits characterize species that have and have not invaded. Predictive models derived from discriminant analysis correctly classified 86.2% of the species in cross‐validation, whereas those derived from classification and regression trees classified 76% correctly. From these models we created a hierarchical predictive tree that allows the user to divide species into three categories: admit (low risk of invasiveness), deny admission (high risk of invasiveness), or delay admission for further analyses and/or monitor intensively (risk cannot adequately be assessed based on only the included attributes). We recommend that species that are highly invasive elsewhere not be allowed into the U.S. and that a more conservative introduction policy using a hierarchical predictive method be employed.

The Rarest of Darwin’s Finches - Peter R. Grant; B. Rosemary Grant (Conservation Biology, 1997)
The Mangrove Finch (Cactospiza heliobates) is unique among Darwin’s finches in its specialized habits and naturally fragmented distribution on individual islands. It has been reported to occupy six patches of mangroves separated to varying degrees on two of the Galápagos islands, Isabela and Fernandina. We present the results of a field study in three of the patches. The species appears to have become extinct on Fernandina and to be restricted now to a maximum of four habitat islands on Isabela. In one of them, Playa Tortuga Negra, we estimate the population of breeding adults to be 10–20 pairs. At another, west of Villamil, the population size is probably now small due to the cutting of mangroves. The other two populations, close to each other east of Punta Moreno, probably hold the largest demes. Their status is unknown. We estimate that the genetically effective size of the combined populations is 30–380 individuals. Because the populations are so small and restricted, they are vulnerable to any disturbance of the environment. This has probably been so throughout their history because they inhabit a fragmented habitat in a tectonically active region. New anthropogenic threats this century are an introduced wasp (Polistes versicolor), which may be a predator on a major food item (insect larvae) of the finches, and destruction of the habitat. Protection of the occupied habitat against human exploitation is required for the preservation of the species because no alternative habitat is known.

Influences of Egg Laying Behavior on Pathogenic Infection of Amphibian Eggs - Joseph M. Kiesecker; Andrew R. Blaustein (Conservation Biology, 1997)
Mass mortality of developing amphibian eggs and larvae from pathogenic infection has been recently documented in some amphibian populations. For example, the pathogenic fungus, Saprolegnia ferax, has been linked with amphibian embryo mortality in the Pacific Northwest. Continued mortality in early life history stages may ultimately contribute to a population decline. We document the prevalence of S. ferax on embryos of three anuran species ( Bufo boreas, Rana cascadae, and Hyla regilla) common to the Pacific Northwest. These species differ in key aspects of their behavior and ecology, and these differences may lead to differential susceptibility to S. ferax. R. cascadae often lays its eggs communally and B. boreas usually deposits its eggs communally. We observed embryos at natural oviposition sites. Eggs laid communally had higher mortality than those laid away from other egg masses. Field experiments that manipulated both the spatial position and timing of egg laying demonstrated that eggs laid later and in closer proximity to communal masses had higher mortality. Our results suggest that eggs in communal masses are highly susceptible to infection with S. ferax.

Threats from Alien Plant Species in the Galápagos Islands - A. Mauchamp (Conservation Biology, 1997)

Trophy Hunting and Wildlife Conservation in Zambia - Dale M. Lewis; Peter Alpert (Conservation Biology, 1997)
For wildlife conservation to succeed in developing countries, people who live in or near protected areas must receive benefits that offset the costs of their reduced access to natural resources. International trophy hunting is currently generating significant economic benefits for residents of game management areas in Zambia. This has been made possible through a revolving fund and an administrative program that direct revenues from trophy hunting to local wildlife management and community development projects. Benefits might be enhanced by better biological information for management, greater local participation in the allocation and operation of hunting concessions, and the promotion of ecological and ethical standards for trophy hunting. An international system of certification for trophy hunting operations could foster these improvements.

Representativeness and Efficiency of Bird and Insect Conservation in Norwegian Boreal Forest Reserves - Jogeir N. Stokland (Conservation Biology, 1997)
I quantified local species richness of birds in different forest types and of beetles in spruce forests at different altitudes. In both cases I quantified timber production as a measure of land acquisition cost and used the ratio between the species richness and timber production as a measure of conservation cost‐efficiency. I found a positive correlation between timber production and local species richness of birds as well as beetles, indicating that the forests most valuable for forestry are also the ones most valuable for biodiversity conservation. I used different selection procedures for combining sites in a reserve network to find the minimum set of sites that included all vulnerable species. The minimum set of sites for birds was 30% spruce forest, 30% pine forest, and 40% broad‐leaved forest (the three main forest types). The minimum set of sites for the beetles was uniformly distributed along the altitudinal gradient. Both minimum sets were most cost‐efficient for species conservation. I suggest that equal coverage of different productivity classes is more efficient for optimizing biodiversity conservation than over‐representing low productivity sites. Less than 1% of Norwegian boreal forests have been protected as nature reserves. The reserve network is fairly representative with respect to altitude, but it is seriously skewed toward low productivity sites. The current network is suboptimal with respect to forest type representativeness, species protection, and cost‐efficiency. This is a result of an inefficient strategy of selecting reserve sites and an unfortunate combination of selection criteria.

A Practice‐based Approach to Ecosystem Management - Ronald D. Brunner; Tim W. Clark (Conservation Biology, 1997)
Ecosystem management is a rapidly evolving philosophy or paradigm of natural resource management intended to sustain the integrity of ecosystems. The problem is that principles of ecosystem management are unsatisfactory for practical purposes. Three major approaches to the problem are evaluated: (1) clarification of the goals of ecosystem management, (2) construction of a better scientific foundation for management decisions, and (3) comparative appraisal of current practices. The evaluation concludes that neither of the first two approaches is necessary or sufficient for better management decisions because better decisions depend upon the complexities of particular contexts. The third, practice‐based approach makes the most of the limited human capacity to cope with the complexities of ecosystem management in order to improve principles of ecosystem management, to inform particular management decisions through improved principles, and to incorporate clearer goals and a better scientific foundation as they become available. The evaluation draws on experience and disciplines beyond conservation biology and natural resource management, including policy sciences.

Fitness in the Endangered Gila Topminnow - Ruby J. Sheffer; Philip W. Hedrick; W. L. Minckley; Anthony L. Velasco (Conservation Biology, 1997)
The Gila topminnow (Poeciliopsis o. occidentalis) is a small, live‐bearing, endangered fish extant in a maximum of nine locales in four separate watersheds in the United States. To determine if these populations differed in their fitness, we obtained samples from the four watersheds and examined them for four fitness correlates: survival, growth rate, fecundity, and bilateral asymmetry. Earlier research found that one population, Sharp Spring, had higher allozyme heterozygosity than the other three and had higher survival, growth rate, and fecundity and lower bilateral asymmetry than a sample from one of the other populations with no polymorphic allozyme loci, Monkey Spring. We also verified that Sharp Spring fish were polymorphic for the same allozyme loci whereas the Monkey Spring population was not. We did not, however, find positive associations of allozyme heterozygosity with the four fitness correlates for the four samples. Because the earlier study had much lower survival, it is likely that the differences resulted from differential response of the two populations to a stressful laboratory environment. Whether this unknown stress occurs in natural environments or its effect is predictive of other stresses remains unresolved. As a result, we concur with suggestions in the draft recovery plan that topminnows from nearby sources be used for reintroductions and that the Sharp Spring stock not be used outside the upper Santa Cruz River drainage.

Plant Reproductive Traits as a Function of Local, Regional, and Global Abundance - William E. Kunin; Avi Shmida (Conservation Biology, 1997)
Most ecological generalizations stem from the study of common organisms, but most species are rare. There are a number of reasons to expect that rare and common species may differ consistently in their characteristics, with possible implications for conservation. Past analyses of this issue, however, have generally considered only a single measure of rarity and have not corrected analyses for the lack of independence in the traits of related species. We compared several reproductive characteristics of Mediterranean annual crucifers as a function of their global range, regional abundance, and local population density in Israel, making use of independent contrast methods to correct for the phylogenetic relationships of the species involved. We found plants growing at low local density to be disproportionately likely to be self‐compatible. Petal length and floral depth (sepal length) were correlated with breeding system but showed significant interaction effects between breeding system and abundance. Floral longevity was inversely related to abundance and also showed significant interaction effects between breeding system and abundance. Overall, rare species tended to display more extreme values for floral traits than did common plants with the same breeding systems; they had unusually large and deep flowers if self‐incompatible and unusually small, shallow ones if self‐compatible.

Old‐Growth Mangrove Forests in the United States - Ariel E. Lugo (Conservation Biology, 1997)
Criteria used to identify old‐growth forests in the Pacific Northwest have not been proven applicable in other ecological life zones. For example, Pacific Northwest criteria are not suitable for the identification of old‐growth mangrove forests. To identify old‐growth mangroves one has to take into account differences in stand structure and function due to geomorphology, within‐site environmental gradients, and regional disturbance regimes. A flexible and holistic approach is needed. Stand age, defined in terms of Pacific Northwest forests, is not necessarily the best criterion for identifying for conservation mangrove forests or any forest outside the Pacific Northwest. No single stand will have all old‐growth characteristics, and even if they are present in a stand, these characteristics do not necessarily assure that the stand is old growth. Whether a mangrove stand reaches old‐growth stage depends on the dynamics of coastal conditions under which it grows. Moreover, it is necessary to differentiate between the age of trees in a stand and the age of the mangrove system, which includes the substrate. Old‐growth mangrove stands are improbable states for this ecosystem type, and they can revert to younger stages. Mangroves offer a challenge to the concept of the old‐growth forest, and through our analysis of this system we show that when ecosystem functions and states are evaluated it is necessary to avoid geographic biases based on particular ecological conditions.

Retrospective Power Analysis - Len Thomas (Conservation Biology, 1997)

Statistical Power Analysis and Amphibian Population Trends - John P. Hayes; Robert J. Steidl (Conservation Biology, 1997)

Modeling the Persistence of Small Populations of Strongly Interdependent Species: Figs and Fig Wasps - Marie‐Charlotte Anstett; Martine Hossaert‐McKey; Doyle McKey (Conservation Biology, 1997)
Conservation problems are usually studied at the population or ecosystem levels. Formulating predictive theory for the domain in between has been difficult. Fig trees and their pollinating wasps, principally tropical groups of organisms, form pairs of obligate mutualists that provide unique opportunities for studying the influence of species interactions on the survival of small populations. Survival of each partner depends on that of the associated species. The pollinator population can be maintained only if figs are produced year‐round. Because fig trees flower synchronously at the individual level, wasps have to locate a new individual host tree at each generation. We describe results of simulation models estimating the minimum number of trees required to maintain a wasp population using two levels of the criteria: (1) different probability of survival (50% and 99%) and (2) different time of survival (5 or 1000 years). We also examined how these different estimates are sensitive to differences in the seasonality of flowering period and in the length of the period of female receptivity in figs. Such estimates can be used to understand the potential effects of the reduction of fig population size via fragmentation. Unlike most studies on the effect of low population size on population viability, our paper focuses on maintenance of a biotic interaction, rather than on single‐species dynamics. The biotic interaction on which we focus is important because figs in many tropical ecosystems may be keystone resources for frugivores that are in turn essential seed dispersal agents for other plants.

Patterns of Rarity in the Birds of the Atlantic Forest of Brazil - Jaqueline M. Goerck (Conservation Biology, 1997)
Patterns of rarity in species are generally explained by several factors: evolutionary history, spatial distribution, and genetic structure of each taxon. Human intervention also leads to or increases rarity in species. The discernment of causes of rarity is essential to the understanding of extinction patterns, and thus to devising conservation strategies. I examine patterns of rarity among bird species in the Atlantic forest region in Brazil, one of the most threatened ecosystems in the world. I assigned bird species to one of eight possible categories that differ in degree of vulnerability and that are based on three parameters of rarity: geographic distribution, habitat specificity, and population size. The Atlantic forest avifauna is a highly endangered group; 68% of the species are rare. Patterns of rarity among the birds in the region likely result from their specific ecologies or evolutionary histories. In addition, human alteration of natural habitats and hunting pressures have undoubtedly influenced rarity for a number of species.

Patches, Corridors, and Matrices (Conservation Biology, 1997)

Geographical Range Size and the Conservation of Mexican Mammals - Héctor T. Arita; Fernanda Figueroa; Astrid Frisch; Pilar Rodríguez; Karina Santos‐Del‐Prado (Conservation Biology, 1997)
Range was estimated for the 423 noninsular mammals of Mexico to identify those species with more restricted distributions and to detect priority areas for conservation based on the presence of such species. Thirty‐eight percent of nonvolant mammals and 15.4% of bats are restricted in Mexico to areas of less than 114,000 km 2 . Restricted species were defined as those occurring in ranges smaller than the median for bats and for nonvolant species. Following this criterion, most nonvolant species with restricted distribution in Mexico are either endemic to the country or are shared with the United States, whereas endemic chiropteran species are few, and most Mexican bats with restricted distribution also occur in South America. Nonvolant mammals with restricted distribution in Mexico tend to be of small body size, herbivore or granivore, and fossorial or semifossorial. Among bats, gleaners are significantly more restricted than aerial insectivores. Species with restricted distribution are inadequately represented in the current official list of endangered species, particularly in the case of nonvolant mammals. Similarly, some areas of Mexico that harbor several species with restricted distribution are not represented in the Mexican system of protected areas. Therefore, rarity, in this case measured by the area of distribution, should be included as an additional criterion for conservation of the Mexican mammal fauna.

The Private-Land Problem - Michael J. Bean; David S. Wilcove (Conservation Biology, 1997)

Archie Carr, Model Naturalist - Archie Carr (Conservation Biology, 1997)

11th Annual Meeting of the Society for Conservation Biology (Conservation Biology, 1997)