A paper recently published by reported a molecular genetic study of all recognized subspecies of the common snapping turtle ( Chelydra serpentina) and concluded from patterns of geographic variation in isozyme and mitochondrial DNA restriction fragment pattern data that three evolutionary species should be recognized in this group. We suggest that this paper is fundamentally flawed because it fails to present any species conce...

We used visual transect surveys to study the effects of forest fragmentation on abundance of two species of Leptodactylid frogs in an Andean forest of northern Ecuador. We measured the abundances of Eleutherodactylus chloronatus and E. trepidotus at various distances from the forest edge in one large forest patch (200 ha) and four adjacent forest fragments (0.25–5.3 ha). We also collected data on forest characteristics ( leaf...

In North America’s Great Basin Desert changes in plant communities that occurred after the introduction of domestic livestock in the late 1800s resulted in the irruption of mule deer (Ocodoileus hemionus) and expansion of mountain lions ( Felis concolor). We report on a situation in which mountain lion predation caused the near‐extinction of another native species, porcupines ( Erethizon dorsatum). We used demographic informat...

The sustainability of the indigenous dugong ( Dugong dugon) fishery in Torres Strait is evaluated on the basis of aerial survey estimates of the size of the regional dugong population in 1987 and 1991 and a survey of catches of dugongs taken by local communities between 1991 and 1993. The estimate of the dugong population in the Torres Strait region in November‐December 1991 was 24,225 (± SE 3,276) compared with the correspond...

We evaluated the consequences of parameter errors for predictions of spatially explicit population models. We examined a simple model for organisms dispersing in a fragmented landscape and assessed how errors in three model input parameters propagate into errors in model predictions: (1) misclassification of habitat suitability (landscape error); (2) incorrect estimation of how far a disperser can travel (mobility error); and...

The natterjack toad ( Bufo calamita) is an endangered species in Britain and has been legally protected since 1975. This amphibian suffered a major decline during the first half of the twentieth century, due partly to habitat destruction but mostly to successional changes in its specialized biotopes and anthropogenic acidification of breeding sites. In addition to site and species protection, extensive autecological research o...

It is generally expected that exploited whale populations should rebuild following the end of whaling. Using photographic identification of individuals during a series of field projects, we studied female and immature sperm whales ( Physeter macrocephalus) that visit the waters off the Galápagos Islands, Ecuador. Analysis of mark‐recapture data, using a likelihood model, indicates the population decreased at a rate of about 20...

This study was prompted by international concern over the expanding global trade in wildlife parts and derivatives. Pinniped (seals, sea lions, fur seals, and walrus) penises purchased in traditional Chinese medicine shops in Asia and North America were examined using molecular genetic techniques. A 261 base pair region of the cytochrome b gene was sequenced for 21 unknown samples, 3 harp seal ( Phoca groenlandica) reference s...

Population ecology and foraging theory can be combined to simulate the population dynamics of hunter‐gatherers and their prey resources. Such simulation study is important to issues of conservation because many of the population processes that link human foragers and their prey occur over time scales that elude both ethnographic and archaeological fieldwork. To demonstrate, we used the model to examine hunter‐gatherer populati...

Over 1,400,000 m of line transect data were collected in collaboration with Ache Indians to determine encounter rates with all large vertebrates in the Mbaracayu Reserve Paraguay. The data were analyzed using logistic regression in order to determine the impact of human hunting on animal encounter rates in the reserve. The method controlled for effects of season, weather, time of day, and habitat in order to statistically isol...

An emerging goal of ecosystem management is to maintain ecosystems within their range of natural variability, which requires attention to pre‐EuroAmerican landscape‐scale processes and corresponding landscape structures (e.g., old‐growth forest distribution). The prevailing “equilibrium” view of ponderosa pine forest landscapes, for example, holds that frequent, low‐intensity surface fires maintained open, park‐like forests of...

Fragmentation of forested landscapes can reduce the reproductive success of birds occupying residual forest patches. Previous studies, however, have focused primarily on how nest predation can change when landscapes become fragmented by agriculture rather than by logging. To determine if predation on artificial nests in forest patches was influenced by the surrounding landscape, we placed ground and shrub nests along the edge...

Many of the recent, widespread declines and disappearances of amphibian populations have taken place in seemingly undisturbed, montane habitats. The question of whether the observed patterns differ from those expected from natural population dynamics is the subject of an ongoing controversy with important implications for conservation. We examined this issue for the Monteverde region of Costa Rica’s Cordillera de Tilarán, wher...