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.

Seasonal trends and primary contributors to the low-frequency soundscape of the Cordell Bank National Marine Sanctuary.

Abstract: Passive acoustic monitoring of ocean soundscapes can provide information on ecosystem status for those tasked with protecting marine resources. In 2015, the National Oceanic and Atmospheric Administration (NOAA) established a long-term, continuous, low-frequency (10 Hz–2 kHz) passive acoustic monitoring site in the Cordell Bank National Marine Sanctuary (CBNMS), located offshore of the central United States of America (U.S.) west coast, near San Francisco, CA. The California Current flows southward along the coast in this area, supporting a diverse community of marine animals, including several baleen whale species. Acoustic data analysis revealed that both large vessels and vocalizing baleen whales contribute to the ambient soundscape of the CBNMS. Sound levels fluctuated by month with the highest levels in the fall and lowest levels in the summer. Throughout the year, very low-frequency (10–100 Hz) sound levels were most variable. Vessels and whales overlap in their contributions to ambient sound levels within this range, although vessel contributions were more omnipresent, while seasonal peaks were associated with vocalizing whales. This characterization of low-frequency ambient sound levels in the CBNMS establishes initial baselines for an important component of this site's underwater soundscape. Standardized monitoring of soundscapes directly supports NOAA's ability to evaluate and report on conditions within national marine sanctuaries.

Further evidence that Antarctic toothfish are important to Weddell seals

Abstract: Antarctic toothfish Dissostichus mawsoni and Weddell seals Leptonychotes weddellii are important mesopredators in the waters of the Antarctic continental shelf. They compete with each other for prey, yet the seals also prey upon toothfish. Such intraguild predation means that prevalence and respective demographic rates may be negatively correlated, but quantification is lacking. Following a review of their natural histories, we initiate an approach to address this deficiency by analysing scientific fishing catch per unit effort (CPUE; 1975–2011 plus sporadic effort to 2018) in conjunction with an annual index of seal abundance in McMurdo Sound, Ross Sea. We correlated annual variation in scientific CPUE to seal numbers over a 43 year period (1975–2018), complementing an earlier study in the same locality showing CPUE to be negatively correlated with spatial proximity to abundant seals. The observed relationship (more seals with lower CPUE, while controlling for annual trends in each) indicates the importance of toothfish as a dietary item to Weddell seals and highlights the probable importance of intra- and inter-specific competition as well as intraguild predation in seal-toothfish dynamics. Ultimately, it may be necessary to supplement fishery management with targeted ecosystem monitoring to prevent the fishery from having adverse effects on dependent species.

Hybridization of Glaucous and Herring Gulls at the Mackenzie Delta, Canada

Abstract: Interbreeding between two holarctic species, the Glaucous Gull and Herring Gull (Larus hyperboreus and L. argentatus) has been documented only at Bear Island (Barents Sea) and Iceland (reviewed by Ingolfsson 1970). Ingolfsson (1970) classified parental and hybrid phenotypes relative to pigmentation patterns of distal primaries, where a hybrid index (HI) of 0 = pure hyperboreus and HI 5 = pure argentatus, although \"an occasional pure bird (argentatus) may score as low as 4.2.\" Based on this system, interbreeding in North America has been suspected. In 595 museum specimens (most taken during the breeding season) of the two species from Canada and Alaska, Ingolfsson (1970) found 7 with HI's of 4.0-4.6, and 26 with HI's of 0.2-1.8. However, with the possible exception of two birds with HI's of 1.8 and 4.0, only two obvious hybrids are known from North America: a bird (HI = 3.6) collected at San Diego, California, and a bird (HI = 3.0-3.5) collected at Pt. Barrow, Alaska (Ingolfsson 1970; Jehl 1971, MS). While working near the Mackenzie Delta, Canada, in August 1984, I observed hybrid hyperboreus x argentatus regularly, and documented the first instance of interbreeding of the two species in North America. During 9-31 August 1984, I used 8x binoculars and a 20-45 x spotting scope to study the frequency of various phenotypes among adults at two breeding sites [Kay Point, Yukon (69ø13'N, 138ø17'W), and Escape Reef, Yukon (68ø59'N, 137ø11'W)], at three loafing sites [Tuktoyaktuk dump and harbor, Northwest Territories (69ø27'N, 133ø05'W), and Pauline Cove, Herschel Island, Yukon (69ø34'N, 138ø55'W)], and once at sea (69ø37'N, 133ø07'W) when gulls were attracted to our drifting boat. Most adults were probably residents because young were being fed at colonies, and the postbreeding dispersal does not begin until late August or early September (Barry and Barry 1982). I distinguished gulls of the hyperboreus-argentatus type from Thayer's Gulls (L. thayeri, of which only two were seen) by their larger size, lighter mantle color, yellow to orange eye rings, pale yellow irises, and, in the case of pure argentatus, their wing-tip pattern (see MacPherson 1961, Smith 1966). I observed and classified each intermediate according to Ingolfsson's (1970) system. Unlike Ingolfsson (1970), I did not collect specimens, and therefore used a larger scale interval (0.5) than his (0.2). This produced less precise classifications. To reduce the chance of including the same individual more than once, data from only one session of observations at each of the six locations were used in the analyses. My HI estimates are based on scrutiny of primaries 7-10; I usually could not see primary 6 adequately. Each gull was missing one or two of primaries 5-8 because of molt. This exposed any pigmentation on the inner vane of at least one primary, but necessitated that HI's be based on 2-4 feathers instead of 5.

Migration pattern of Gambel’s White-crowned Sparrow along the Pacific Flyway

Abstract: White-crowned Sparrow (Zonotrichia leucophrys) populations of western North America exhibit dramatic differences in life history strategies including migration behavior However, individual migration strategies and population-level migratory patterns remain largely unknown for this species Here, we focused on the long-distance migratory subspecies, Gambel’s White-crowned Sparrow (Zonotrichia leucophrys gambelii) We used ringing, tracking and stable hydrogen isotope (δ2H) analysis of individuals migrating along the Pacific Flyway to assess individual phenology and routes as well as the pattern of connectivity between breeding and non-breeding sites Results from all three methods, consisting of 79 ring recoveries, four light level geolocator tracks and 388 feather δ2H values, indicate low degrees of migratory connectivity The isotope data provide evidence for leapfrog migration with the more southerly populations traveling greater distances to the breeding grounds than more centrally wintering individuals Location estimates of four annual journeys revealed individually consistent migration strategies with relatively short flight bouts separated by two to three and two to six stopover sites during spring and autumn migration, respectively However, combined results from all methods indicate high variability in migration distance among individuals These findings confirm the phenotypic flexibility observed within this species and highlight the potential of White-crowned Sparrows for further investigations of evolutionary adaptations to ongoing changes in the environment

Evaluating Riparian Restoration Success: Long-Term Responses of the Breeding Bird Community in California’s Lower Putah Creek Watershed

Abstract: Restoration of river processes and riparian vegetation is a high priority, particularly in the western United States, where it provides critical habitat for fish and wildlife along with many other environmental and economic benefits, yet few studies have quantified long-term responses of wildlife. We evaluated responses of the breeding bird community to restoration and management of the lower Putah Creek watershed in the Central Valley of California following the establishment of the Putah Creek Accord in 2000, an historic agreement designed to improve ecosystem structure and function and protect the livelihoods of farmers and residents along the lower creek. We surveyed the breeding bird community at 14 sites distributed over 38 km of the creek between 1999 and 2012, and we detected significant increases in the abundance of 27 breeding bird species as well as increases in the size and diversity of the entire breeding bird community, which could not be accounted for by broader regional trends or the influence of local nest box installation. Further, changes in the watershed favored riparian and woodland-associated species over synanthropic species. However, in comparison with Central Valley Joint Venture density objectives for seven riparian focal bird species, there is still considerable room for improvement, particularly at sites farthest downstream. Overall, our results echo shifts in the Putah Creek fish community and provide evidence that the Putah Creek Accord and subsequent management actions have contributed to a long-term improvement in riparian ecosystem condition for both aquatic and terrestrial organisms.