California Institute of Environmental Studies

Davis, CA, United States

California Institute of Environmental Studies

Davis, CA, United States
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Anderson D.W.,University of California at Davis | Anderson D.W.,California Institute of Environmental Studies | Henny C.J.,U.S. Geological Survey | Godinez-Reyes C.,CONANP SEMARNAT | And 5 more authors.
Marine Ornithology | Year: 2014

In 2009, the Brown Pelican Pelecanus occidentalis was removed from the US Endangered Species List. The California subspecies P. o. californicus (hereafter CABRPE) was also removed from the California state endangered species list. Three years earlier (2006), we estimated the metapopulation of CABRPE to be 70 680 ± 2 640 breeding pairs (mean ± SD) and 195 900 ± 7 225 individuals. The largest single breeding aggregation within the range occurred among two to three islands of the San Lorenzo Archipelago, Gulf of California (GOC), totaling ~17 225 breeding pairs, or ~24.4% of the metapopulation. This and the other 4 subpopulations were composed of a single "core" breeding aggregation (on one or a few adjacent islands) and many smaller but isolated colonies (a colony represents all birds on a single island). Extremely small colonies (<65 nests) made up ~35.6% of total colonies, but only ~ 0.9% of the total estimated numbers, corrected for detectability. Modal colony size throughout the range was much smaller (230 to 1 300 breeding pairs), indicating that small, scattered colonies and sub-colonies have a function in CABRPE distributional dynamics and demography. Thus, negative single-survey data (no occupancy and small numbers) still have conservation importance as alternate or growing colonies in source-sink dynamics. Little numerical change in CABRPE in at least three decades was indicated from less precise data south of the northernmost Southern California Bight (SCB) subpopulation, but significant recent improvements in the SCB were reflected by our high estimates in 2006, supporting the USFWS delisting. At that time, we estimated the improved SCB breeding population as 11 695 ± 450 pairs. However, continuing threats throughout the range, especially in the south, now include commercial fishing, tourist developments, increased human activities, and extensive/expanding aqua-cultural developments (as well as, to a lesser degree, agricultural activities). Repeated endangerment is a possibility. Continued monitoring will be important.

Robison K.M.,University of California at Davis | Robison K.M.,Colibri Ecological Consulting LLC | Anderson D.W.,University of California at Davis | Anderson D.W.,California Institute of Environmental Studies | And 2 more authors.
Waterbirds | Year: 2015

Western (Aechmophorus occidentalis) and Clark's (A. clarkii) grebes are long-lived, migratory waterbirds that are sensitive to human-caused disturbance while nesting. Sampling the age distribution of post-hatch chicks provides a method for estimating the timing of nest initiation without causing disturbance to breeding colonies. The goals of this work were to describe trends in breeding productivity at two of the largest nesting colonies in northern California and illustrate how brood size can be used to evaluate nesting phenology in Aechmophorus grebes. No differences were found in brood size between species. Brood size decreased linearly as nest initiation date increased, showing no differences in the rate of decline among age classes of young. Within seasons, older broods were found to be significantly smaller than younger broods, suggesting that mortality was occurring after hatching thereby reducing the potential number of chicks recruited into the adult population.

Wallace S.J.,Queen's University | Wolf S.G.,Center for Biological Diversity | Bradley R.W.,Point Blue Conservation Science formerly PRBO | Harvey A.L.,California Institute of Environmental Studies | Friesen V.L.,Queen's University
Journal of Biogeography | Year: 2015

Aim: Our aim was to investigate the influence of biogeographical barriers along the Pacific coast of North America on population genetic structure and gene flow using Cassin's auklet (Ptychoramphus aleuticus) as a test case. Location: We collected samples from 287 Cassin's auklets breeding along the Pacific coast of North America from the Aleutian Islands, Alaska, USA, to Baja California, Mexico. Methods: We amplified a 706 base pair fragment of the mitochondrial control region and 11 microsatellites to obtain independent estimates of population genetic structure and gene flow among colonies using programs based on coalescent and Bayesian theory. We tested whether genetic differentiation was related to geographical distance between sampling sites, and whether gene flow has occurred between differentiated groups. Results: We found two distinct genetic groups along the Cassin's auklet breeding range. These clusters matched the current subspecies designations, except that individuals breeding in the Channel Islands, California, were traditionally classified with the northern subspecies but were more genetically similar to the Baja California subspecies. Population genetic differentiation was not evident within either of the two genetic groups, despite large geographical distances between sampling locations. Evidence suggests that gene flow has occurred from the northern genetic group (Aleutian Islands to Southeast Farallon Islands) into the southern genetic group (Channel Islands to San Benito Island) since divergence, but gene flow may not have occurred in the opposite direction. These results suggest that a barrier to gene flow from south to north may occur at Point Conception. Main conclusions: Although a relatively short geographical distance occurs between sampling sites of Cassin's auklets across Point Conception, individuals breeding north of Point Conception are genetically differentiated from individuals breeding in southern California and Baja California. Population genetic differentiation of the southern genetic group provides support for a role of a barrier to gene flow around Point Conception in generating biodiversity in this area. © 2015 John Wiley & Sons Ltd.

Harvey A.L.,Channel Islands National Park | Mazurkiewicz D.M.,Sutil Conservation Ecology | McKown M.W.,Conservation Metrics Inc | Barnes K.W.,Sutil Conservation Ecology | And 2 more authors.
Marine Ornithology | Year: 2016

Ashy Storm-Petrels (ASSP) breed in a range restricted to the southern California Current, from Mendocino County in northern California, United States, to the Coronado Islands in northwest Baja California, Mexico. Approximately half the global population nests on the California Channel Islands, but nesting at one of them, Anacapa Island, had not been recorded before this study. In 2011, 10 years af ter rats were eradicated, we conducted a study to determine the breeding status of ASSP on Anacapa Island. We used habitat searches coupled with acoustic sensors to assess potential nesting areas and conducted mist netting to determine general presence. We found one active nest containing a nearly fledged ASSP chick in 2011, representing the first breeding record for the island. © 2016, Marine Ornithology. All rights reserved.

Adams J.,U.S. Geological Survey | Carter H.R.,Humboldt State University | McChesney G.J.,Humboldt State University | McChesney G.J.,U.S. Fish and Wildlife Service | And 2 more authors.
Marine Ornithology | Year: 2016

We mist-netted and examined Leach’s Storm-Petrels Oceanodroma leucorhoa (LESP) caught during 1991-2015 at three locations in the California Channel Islands (CCI): Prince Island, Santa Barbara-Sutil islands and Scorpion Rock. Although mist-netting methods and effort varied between two study periods (1991-1995, 2004-2007 and 2015), during 750 h effort we captured 41 LESP during April-August, with two of these recaptured after initial banding. The majority (78%) were classified as likely breeders based on a well-developed incubation patch. We summarize island-specific efforts, capture rates and morphological measurements made at these three CCI locations. Captured LESP displayed a multimodal distribution in the overall degree of white rump plumage, with 28% classified as mostly “dark-rumped.” The majority of LESP (72%) captured in the CCI have variable white rumps, similar to what has been reported for northern California and the Farallon Islands. However, the relative proportions of “dark-rumped” individuals captured in the northern CCI is intermediate, within the shift starting at the Farallon Islands and increasing in prevalence toward the San Benito Islands, Baja California. More remains to be learned about LESP in the CCI, for which additional mist-netting efforts are needed, using a standardized approach that targets LESP. © 2016, Marine Ornithology. All rights reserved.

Birt T.P.,Queen's University | Carter H.R.,California Institute of Environmental Studies | Whitworth D.L.,California Institute of Environmental Studies | McDonald A.,Queen's University | And 6 more authors.
Auk | Year: 2012

Population genetic structure was characterized in Xantus's Murrelet (Synthliboramphus hypoleucus) by analyzing variation in the mitochondrial control region (505 samples) and 12 microsatellite loci (428 samples) in birds captured at all 13 current breeding areas in southern California and northwestern Baja California, Mexico. The two types of molecular markers were consistent in revealing strong genetic differentiation between the two currently recognized subspecies (S. h. hypoleucus and S. h. scrippsi) and little or no differentiation among breeding areas within subspecies. Estimates of gene flow were essentially zero, and no evidence for admixture was found. Gene flow among breeding locations within subspecies, on the other hand, was seemingly high. Given these genetic results, as well as clear morphological differences between the subspecies and the apparent lack of interbreeding at breeding areas where the two forms are sympatric, we suggest that two species be recognized. Both forms are genetically distinct from Craveri's Murrelet (S. craveri), a closely related species whose breeding range partially overlaps that of Xantus's Murrelet. Taxonomic subdivision of Xantus's Murrelet introduces new conservation concerns, especially for S. h. hypoleucus, which urgently requires greater study and protective efforts. © The American Ornithologists' Union, 2012.

Barbaree B.A.,Oregon State University | Nelson S.K.,U.S. Geological Survey | Dugger B.D.,Oregon State University | Roby D.D.,U.S. Geological Survey | And 3 more authors.
Condor | Year: 2014

Studying the ecology of endangered species in portions of their range where the population remains abundant can provide fundamental information for conservation planners. We studied nesting by radio- Tagged Marbled Murrelets (Brachyramphus marmoratus) during 2007 and 2008 in Port Snettisham, a relatively pristine, remote mainland fjord in southeast Alaska with high at-sea densities of Marbled Murrelets during the breeding season. Of 33 active Marbled Murrelet nest sites located during the study, we found 15 within forested habitat (tree nest sites), 16 in nonforested habitat (ground nest sites), and 2 that could not be determined. Some nests were located farther inland from the coast (range: 1-52 km) and at higher elevations (range: 42-1,100 m) than previously documented in Alaska. Nesting success to 20 days posthatch (0.20 6 0.07 [SE]) was less than half of similar estimates in British Columbia and more comparable to estimates from California and Washington. A logistic regression found that nesting success did not differ between years, but nesting success was higher for tree nests than for ground nests. Conservation planners should consider that Marbled Murrelets will use certain nonforest habitat types for nesting in mainland southeast Alaska. Our reported nesting success was likely a maximum, and our results indicate that nesting success can be low even when nesting habitat is seemingly abundant and marine habitat appears excellent. © 2014 Cooper Ornithological Society.

Becker B.H.,Pacific Coast Science and Learning Center | Carter H.R.,California Institute of Environmental Studies | Carter H.R.,Humboldt State University | Henderson R.P.,California Institute of Environmental Studies | And 3 more authors.
Marine Ornithology | Year: 2016

While the largest Ashy Storm-Petrel Oceanodroma homochroa (ASSP) colonies are at offshore islands, small colonies also occur along the mainland coast of northern and central California. We describe past and current monitoring efforts along the coastline of Point Reyes National Seashore, California. From 2012 to 2015, we conducted nest searches and mist netting in late August or early September at the Bird Rock and Stormy Stack colonies, as well as the Point Reyes Headlands. Potential nest sites on Stormy Stack (~17) and Bird Rock (~40) included 4-7 and 3-6 active nests, respectively. These nest numbers were similar to those from past complete surveys at Bird Rock in 1989 and Stormy Stack in 2001, suggesting little change in colony size over time. Birds per capture hour during single nights of mist-netting at Bird Rock in 2012 (1.46) and 2013 (1.44) were lower than on two nights in 1989 (5.47 and 3.08), leading to a higher estimate of 37 pairs in 1989. Two ASSP were also netted at the Point Reyes Headlands in 2013, but no nests were found during limited searches in 2013 and 2015. Standardized long-term monitoring of nests at Bird Rock and Stormy Stack will provide better information on future population trends and conservation issues. © 2016, Marine Ornithology. All rights reserved.

Carter H.R.,California Institute of Environmental Studies | Parker M.W.,California Institute of Environmental Studies | Koepke J.S.,California Institute of Environmental Studies | Whitworth D.L.,California Institute of Environmental Studies
Western Birds | Year: 2015

In August 2012, we confirmed breeding by an estimated 50 pairs of Ashy Storm-Petrels (Oceanodroma homochroa) at four nearshore rocks (Franklin Smith Rock, Wharf Rocks, Casket Rock, and SrJllwell Point Rock) along the central coast of Mendocino County, California. Nesting in this region at the northern end of the species' range was first discovered in 1926, when four eggs were collected by Franklin J. Smith on nearshore rocks and preserved in private collections but not published. Ashy Storm-Petrel colonies were not detected north of Marin County during major surveys of seabird colonies in 1969,1979-1980, or 1989, but specific efforts to detect storm-petrels were made at only a few rocks. In 2012, we did not find Ashy Storm-Petrels breeding north of Stillwell Point Rock (39.3° N), which appears to be the current northern limit of the species' breeding range.

Whitworth D.L.,California Institute of Environmental Studies | Carter H.R.,Humboldt State University | Gress F.,California Institute of Environmental Studies
Biological Conservation | Year: 2013

Eradication of introduced predators has become an increasingly important restoration strategy on islands since the 1970s, but the benefits for impacted seabird populations are seldom examined. Scripps's murrelet (Synthliboramphus scrippsi), a small crevice nesting alcid, suffered severe impacts from introduced mammals at all breeding islands through much of the 19th and 20th centuries. From 2001 to 2010, nest monitoring was conducted to assess responses of the remnant murrelet population at Anacapa Island, California after black rats (Rattus rattus) were eradicated in 2002. Baseline (2001-2002) and post-eradication (2003-2010) monitoring in ten sea caves recorded a nearly 3-fold increase in hatching success (30% versus 85%), due mainly to a drastic reduction in egg predation. Post-eradication monitoring in caves was augmented with three plots in previously vacant "non-cave" habitats that were occupied within 1-3. years of rat eradication. Nests increased 10% per annum in sea caves, 24% in non-cave plots and 14% overall. Murrelet nesting was limited mostly to remnant breeding habitats, consistent with recruitment of philopatric local cohorts as the major factor in colony growth. No nests were found during limited searches of suitable crevices on upper-island slopes and cliffs. Continued monitoring at Anacapa is needed to document the long-term progress and rate of colony recovery and detect nesting in currently vacant habitats. Better knowledge of the post-eradication responses of seabirds will assist development of more effective island restoration actions; thus, baseline and post-eradication monitoring should be essential components of more eradication programs in the future. © 2013 Elsevier Ltd.

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