Institution
Point Blue Conservation Science
Nonprofit•Petaluma, California, United States•
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.
Topics: Population, Foraging, Climate change, Habitat, Pygoscelis
Papers published on a yearly basis
Papers
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TL;DR: The practice of variable drawdown successfully extended the availability of waterbird habitat provided by post-harvest flooded rice fields later into winter.
Abstract: Wetland loss and degradation have been extensive across the world, especially in California's Central Valley where over 90% of the natural wetlands have been converted to agricultural and urban uses. In the Central Valley today, a much smaller network of managed wetlands and flooded agricultural fields supports almost five million waterfowl and half a million shorebirds. Over 50% of waterbird habitat in the Central Valley is provided by flooded agricultural land, primarily rice (Oryza sativa). Each year non-breeding waterbird habitat decreases in the late winter as flooded agricultural fields are drained after waterfowl hunting season in late-January to prepare for the next crop. This study evaluated a practice called 'variable drawdown' that involves delaying the removal of water from rice fields by 1, 2, and 3 weeks to extend the availability of flooded habitat later into February and March. We studied waterbird response to variable drawdown in 2012 and 2013 at twenty rice farms throughout the northern half of the Central Valley. The staggered drawdown created a mosaic of water depths throughout the six-week study period. The 3-week delay in drawdown supported more dabbling ducks than earlier drawdowns in the first half of the study and more shorebirds and long-legged wading birds during the second half of the study. The timing of highest use of each drawdown treatment differed for each waterbird guild; dabbling ducks, geese and swans benefited at the beginning, then long-legged wading birds, followed by shorebirds. Despite the presence of appropriate water depths for shorebirds across the treatments during the entire study period, shorebird densities were highest near the end of the study when the 3-week-delayed drawdown was providing the majority of the habitat on the landscape. This suggests that shorebirds may have concentrated in our study fields due to decreasing availability of shallow water habitat elsewhere. The practice of variable drawdown successfully extended the availability of waterbird habitat provided by post-harvest flooded rice fields later into winter.
14 citations
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TL;DR: A strong inference path is suggested that incorporates what the authors know about population dynamics in penguins and Ross Sea food webs into life history parameterizations of penguins, toothfish and silverfish population dynamics models and effectively test the prey release hypothesis.
14 citations
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TL;DR: Commentaries on the modified version of the H-P system represents a significant improvement in terminology, and will better reflect the homologies of molts and the first plumage cycle are offered.
Abstract: In this issue, Jenni and Winkler, Piersma, Thompson, and Willoughby offer commentaries on our modifications (Howell et al. 2003) to the Humphrey-Parkes system for naming molts and plumages (Humphrey and Parkes 1959; the H-P system). Piersma generally accepts our revision and outlines how its use could improve our ability to understand other cyclic life-history phenomena. Both Jenni and Winkler and Willoughby disagree with the philosophy of the H-P system, particularly its ability to reveal homologies. Thompson accepts the H-P system but argues that our elaboration on the system is faulty. However, we believe that despite a diversity of opinion concerning our proposal there is much common ground, including agreement regarding the homology of juvenal and basic plumages across species and the utility of the new term “formative.” The main points we review here are the potential dichotomy between homologies of molt and homologies of plumage coloration; the caution that should be applied when using plu...
13 citations
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University of St Andrews1, University of Exeter2, Swansea University3, Royal Society for the Protection of Birds4, University of Montpellier5, Percy FitzPatrick Institute of African Ornithology6, University of Leeds7, Point Blue Conservation Science8, Natural Environment Research Council9, University of Liverpool10, British Antarctic Survey11, University of Glasgow12, University of Auckland13
TL;DR: Analysis of geolocation and stable isotope data across multiple years to investigate individual variation in the non-breeding movements and diets of northern gannets Morus bassanus indicates that a consistent migratory strategy can be effective regardless of wintering region or diet, but that there may be additional benefits to those individuals able to display increased flexibility.
Abstract: Migration is a fundamental behavioral process prevalent among a wide variety of animal taxa. As individuals are increasingly shown to present consistent responses to environmental cues for breeding or foraging, it may be expected that approaches to migration would present similar among-individual consistencies. Seabirds frequently show consistent individual differences in a range of traits related to foraging and space-use during both the breeding and non-breeding seasons, but the causes and consequences of this consistency are poorly understood. In this study, we combined analysis of geolocation and stable isotope data across multiple years to investigate individual variation in the non-breeding movements and diets of northern gannets Morus bassanus, and the consequences for changes in body condition. We found that individuals were highly repeatable in their non-breeding destination over consecutive years even though the population-level non-breeding distribution spanned >35° of latitude. Isotopic signatures were also strongly repeatable, with individuals assigned to one of two dietary clusters defined by their distinct trophic (δ15N) and spatial (δ13C) position. The only non-breeding destination in which the two dietary clusters co-occurred was off the coast of northwest Africa. The majority of individuals adopted a consistent foraging strategy, as they remained within the same dietary cluster across years, with little variation in body mass corrected for size among these consistent individuals. In contrast, the few individuals that switched clusters between years were in better condition relative to the rest of the population, suggesting there may be benefits to flexibility during the non-breeding period. Our results indicate that a consistent migratory strategy can be effective regardless of wintering region or diet, but that there may be benefits to those individuals able to display flexibility. This appears to be an important behavioral strategy that may enhance individual condition.
13 citations
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TL;DR: In this article, the authors observed that harbor seals of San Francisco Bay, California, have a higher incidence of red pelage than is observed along the outer eastern-Pacific coast or elsewhere in the world.
Abstract: Harbor seals of San Francisco Bay, California, have a higher incidence of red pelage (range, 4–32% of the total count) than is observed along the outer eastern-Pacific coast or elsewhere in the world. Red pelage was observed among all sex and age classes, except for pups. The pattern of red coloration on the body varied; most seals had red hair extending from the head down to the shoulder. Elemental analyses of hair samples revealed that red coloration was from deposition of iron oxide precipitates on the hair shaft. We postulate that the particular conditions within San Francisco Bay, including large areas of shallow water and strong summer winds with resuspension of sediments, bring sufficient quantities of ferrous iron from the sediments into the water column where it may serve as a principal source of the ferric oxide deposited on pelage of seals.
13 citations
Authors
Showing all 153 results
Name | H-index | Papers | Citations |
---|---|---|---|
Keith A. Hobson | 103 | 653 | 41300 |
John A. Wiens | 75 | 193 | 26694 |
David G. Ainley | 61 | 200 | 10383 |
William J. Sydeman | 57 | 180 | 13698 |
Grant Ballard | 38 | 98 | 3643 |
Steven D. Emslie | 36 | 126 | 3595 |
Nadav Nur | 34 | 87 | 3479 |
C. John Ralph | 28 | 72 | 3848 |
Larry B. Spear | 26 | 55 | 2542 |
Matthew D. Johnson | 25 | 62 | 3309 |
David F. DeSante | 24 | 62 | 2462 |
Nathaniel E. Seavy | 24 | 67 | 1780 |
Gary W. Page | 24 | 48 | 2679 |
Harry R. Carter | 23 | 97 | 1640 |
Jaime Jahncke | 23 | 76 | 1628 |