Harbor porpoises have been well studied in locations worldwide, but relatively little research has focused on site fidelity of individuals, which influences population structure and determines appropriate management and conservation measures. This study investigated the site fidelity and behavior of harbor porpoises through long-term, land-based photo-identification around Fidalgo Island, Washington, USA. Individuals were cons...

Little is known about the in-water behavior and site fidelity of harbor seals (Phoca vitulina richardii), as most photo-identification (photo-ID) studies are typically conducted while they are hauled-out on land. We investigated in-water site fidelity rates and seasonal presence in Burrows Pass, Washington, using photographs collected during a long-term photo-ID and behavioral study from January 2015 through November 2019. The...

Harbor porpoises are typically seen in small groups of 1–3 individuals, with aggregations of 20+ individuals treated as rare events. Since the 1990s, the harbor porpoise population in the Salish Sea has seen a significant recovery, and an increased number of observed aggregations that exceed the more usual small group sizes has been observed in recent years. By combining the observational data of United States and Canadian res...

Demographic changes can result in alterations of social structure and behavior which in turn may affect survival, reproduction, or movement and may influence how populations respond to changes in the environment. In 2013, 52 Atlantic spotted dolphins ( Stenella frontalis ) left Little Bahama Bank (LBB) and immigrated into a resident group of spotted dolphins on Great Bahama Bank (GBB). Initially there was little interaction an...

The harbor porpoise ( Phocoena phocoena ) is one of the most abundant coastal cetacean species in the Northern Hemisphere with differential levels of regional knowledge. Gaps are particularly evident for the Pacific subspecies Phocoena phocoena vomerina . In the Salish Sea (a transboundary body of water spanning between Washington, United States and British Columbia (BC), Canada), there is a dearth of information on many aspec...

Harbor porpoise (Phocoena phocoena) diets are predominantly comprised of small fish species (<30 cm) and squid. However, predation on larger species (up to 63 cm) occurs, raising the question of increased risk of asphyxiation associated with this behavior. Literature was reviewed and stranding data from 1983 to 2020 from the U.S. West Coast (including California, Oregon and Washington) were searched for cases of prey-related a...

Little is known about harbor porpoises at the individual level or local group structure. Group characteristics, site fidelity, and photo‐identification of harbor porpoises were investigated off Fidalgo Island, Washington State. Harbor porpoise presence was affected by season and rip tide strength (Wald χ 2 P 2 P n = 266) was influenced by season, behavior, and calf presence ( F 7 = 9.71, P R 2 = 0.294). Fifty‐three individuals...

Animal populations can be affected by environmental disturbances in many ways including demographic and behavioral changes. This can affect interspecies associations for regularly interacting sympatric species, like bottlenose and spotted dolphins in the Bahamas (observed since 1985 and interspecies associations analyzed since 1993). After two hurricanes in 2004 each species lost roughly 30% of their respective communities res...

With the exception of primates, detailed interspecies behavioral studies are rare in mammalian species and for cetaceans, most are anecdotal descriptions. This study is the first long‐term study on interspecies associations of regularly interacting groups. In the Bahamas Atlantic bottlenose ( Tursiops truncatus ) and spotted dolphins ( Stenella frontalis ) regularly form mixed species encounters ( MSE ). Both species show stro...

Long‐term social structure data on small delphinids is lacking for most species except the bottlenose dolphin. This study describes the long‐term social structure of one community of Atlantic spotted dolphins, Stenella frontalis, divided into three social clusters. Data from 12 yr were analyzed using SOCPROG 2.3. Coefficients of association (CoA) were calculated using the half‐weight index. The overall mean community CoA range...

Extreme environmental events and demographic changes can have variable effects on the social structure of animal populations. This study compared the social structure of a community of Atlantic spotted dolphins in the Bahamas before and after two hurricanes. Approximately 36% of the individuals were lost, with no subsequent increase in immigration. The majority of the social structure characteristics were consistent with resul...

Fission‐fusion dynamics typical of many delphinid populations allow for a variety of social grouping patterns. Identifying these groupings is crucial before conducting a detailed social structure analysis. This study analyzed the structure of a population of Bahamian spotted dolphins, Stenella frontalis . Through long‐term observations and preliminary analysis, three clusters were defined: Northern, Central, and Southern. To q...

Environmental variations can influence the structure of ecological communities that in turn alter the grouping and association patterns of social communities. This study compares the social structure of bottlenose dolphins in the Bahamas before and after two major hurricanes. Approximately 30% of regularly seen individuals disappeared after the hurricanes, with an equal number of immigrants arriving afterwards. The primary goa...