Point Blue Conservation Science

About: Point Blue Conservation Science is a nonprofit organization based out in Petaluma, California, United States. It is known for research contribution in the topics: Population & Foraging. The organization has 151 authors who have published 330 publications receiving 11929 citations. The organization is also known as: Point Reyes Bird Observatory.

Initial growth of northern fur seal (Callorhinus ursinus) colonies at the South Farallon, San Miguel, and Bogoslof Islands

Abstract: Understanding the colonization or recolonization of breeding sites used by colonial animals is fundamental to metapopulation theory and has practical applications in conservation biology. Historically, pinniped species were heavily exploited worldwide, resulting in some breeding colonies becoming extirpated. As populations recover, some abandoned sites may be recolonized or new sites can be colonized. We analyzed aerial and ground survey data on pup counts from 3 islands (South Farallon, San Miguel, and Bogoslof) (re)colonized by northern fur seals (Callorhinus ursinus), using classical and Bayesian state-space modeling approaches to describe population growth rates during their initial 21 years, with particular focus on the South Farallon Islands. We used information from tagged animals that immigrated to the South Farallon Islands from San Miguel Island to describe the age and sex structure of the founding recolonizers of the South Farallon Islands. We also examined the evidence for the generality of Roux's (1987) description of fur seal population recovery using a literature review of published fur seal population growth rates. We found the 3 colonies had different annual population growth rates (South Farallon = 34%, San Miguel = 45%, Bogoslof = 59%), but all were growing at rates among the fastest observed for fur seals worldwide. Immigrants from San Miguel to the South Farallon Islands were younger and femalebiased relative to the tagged population at San Miguel Island. The general framework described by Roux (1987) was an effective description of observed fur seal population recovery. Our results inform our understanding of the initiation and growth of pinniped breeding colonies.

Projecting long-term impacts of a mortality event on vertebrates: incorporating stochasticity in population assessment

Abstract: Wildlife managers must be able to assess the long-term, population-wide impacts of mortality events on long lived vertebrates, taking into account the stochastic nature of population fluctuations. Here, we present a case study of the potential impacts onWestern gulls (Larus occidentalis) of a single, non-target mortality event, potentially resulting from exposure to rodenticide directed at eradicating house mice (Mus musculus) on the Farallon Islands National Wildlife Refuge. Firstly, we conducted a population viability analysis based on over 25 yr of Farallon Western gull demographic data to model future population trends under varying environmental conditions. Future population trends for Farallon Western gulls, independent of any potential mouse eradication-related mortality, depend on the frequency of years with near-failure in reproductive success, as was observed in 2009, 2010, and 2011. We modeled population trends under three environmental scenarios defined by the probability of near-failure in future breeding: optimistic (probability of nearfailure = 0.0), realistic (probability = 0.115), or pessimistic (probability = 0.25). Secondly, we determined the maximum level of additional mortality, C, that would result in a population outcome distribution that cannot be effectively distinguished from a no additional mortality scenario after 20 yr (defined as 95% overlap in the two frequency distributions). We determined the threshold of detection to be an additional mortality of 3.3% beyond normally observed levels under the realistic scenario, 2.8% under the optimistic scenario, and 4.2% under the pessimistic scenario. Results demonstrate that the greater the background stochasticity, the greater C must be to be able to discriminate a long-term effect of the mortality event against the backdrop of environmental variability. We demonstrate that incorporation of stochasticity is critical for evaluating one-time mortality events given the high degree of variability characterizing many ecosystems; deterministic projections alone may provide poor guidance. While the need to account for stochasticity in Population Viability Analysis models is well established, this study is innovative in addressing how to evaluate a future or retrospective one-time mortality event in the context of stochasticity. Our approach can help resource managers’ plan for both bestcase andworst-case scenarios when evaluating impacts of mortality events.

The Natural Introduction of Hectopsylla Psittaci, a Neotropical Sticktight Flea (Siphonaptera: Pulicidae), on Cliff Swallows in California, USA

Abstract: Nineteen specimens of Hectopsylla psittaci were collecled from 2 specimens of Cliff Swallow, Petrochelidon pyrrhonota , captured in misl nets at the Point Reyes Bird Observatory, Marin Co., California, in 1977 and 1978. This is the first record from North America of the natural introduction of this Neotropical sticktight flea. A single previous record apparently resulted from introduction with a shipment of Neotropical birds into lhe San Diego Zoo.

Maintenance of nest quality in Adélie penguins Pygoscelis adeliae: an additional benefit to life in the center

Abstract: In colonial seabirds, differences in the nesting or fledging success have been associated with differences in nest position within the breeding aggregation (subcolony): less successful nests are located on the periphery, with more successful nests closer to the center. For Pygoscelid penguins, central nests tend to be larger, with nest size being an indicator of individual quality because stones must be gathered singly, so more stones reflect more individual effort. Competition for nest materials, including the collection of materials from another’s nest, has also frequently been described in penguins and other colonial seabirds. We used the data collected during the incubation stage from a total of 20 subcolonies at two separate breeding colonies of Adelie penguins (Pygoscelis adeliae) on Ross Island (Antarctica) to test the influence of nest position on breeding success. We also investigated how competition for nest stones could occur at different intensities depending on size of the subcolony, nest position, and quality within a subcolony. We found that peripheral nests experienced lower breeding success and higher number of individuals attempting to remove stones with higher removal success rates than from nests toward the center. The higher costs associated with maintaining and defending nests that incur higher removal pressure could be an additional factor involved in the lower breeding success of peripheral nests.

A Potential New Colony of Ashy Storm-petrels on the Mainland Coast of California, USA

Abstract: We report evidence of likely nesting of the Ashy Storm-petrel (Oceanodroma homochroa) on islets adjacent to Vandenberg Air Force Base in northern Santa Barbara County, California, USA. Ten storm-petrels, along with extensive suitable habitat in the area, suggest a small colony of breeding birds. Other offshore islets along California’s central coast might hold small numbers of storm-petrels. In addition, there are possibly breeding storm-petrels in suitable remote mainland areas, such as at Vandenberg Air Force Base.