San Francisco Bay Bird Observatory

Milpitas, CA, United States

San Francisco Bay Bird Observatory

Milpitas, CA, United States
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Athearn N.D.,U.S. Geological Survey | Athearn N.D.,U.S. Fish and Wildlife Service | Athearn N.D.,University of California at Davis | Takekawa J.Y.,U.S. Geological Survey | And 5 more authors.
Hydrobiologia | Year: 2012

Salt evaporation ponds are used in place of lost natural estuarine habitats for foraging and roosting by waterbirds around the world, but have started to be decommissioned in some areas due to low profitability. In San Francisco Bay, three former salt pond complexes (Alviso, Eden Landing, and Ravenswood) have been decommissioned, i. e., taken out of commission, and are planned for marsh restoration. We compared total and foraging abundance and densities of ducks, shorebirds, and piscivores, as well as eared grebes (Podiceps nigricollis) among decommissioned and commercial pond complexes. Complex use was consistent within groups and variable among groups, with most use occurring in decommissioned ponds: 73% of ducks were observed in the Alviso complex and 9% in the commercial ponds; 51% of shorebirds were in the Eden Landing complex and only 17% in commercial ponds; and 56% of piscivores were in the Alviso complex and <18% in commercial ponds. Only eared grebes were more abundant (59%) in commercial ponds. Differences among groups in within-complex and within-pond abundance were likely related to pond salinity and topography, respectively. Our results suggest that the effects of pond conversion on waterbird groups may be disproportionate to pond area depending on the characteristics of the converted ponds. © 2012 Springer Science+Business Media B.V. (outside the USA).


Wheat R.E.,University of California at Santa Cruz | Lewis S.B.,U.S. Fish and Wildlife Service | Wang Y.,San Francisco Bay Bird Observatory | Levi T.,Oregon State University | Wilmers C.C.,University of California at Santa Cruz
Movement Ecology | Year: 2017

Background: Quantifying individual variability in movement behavior is critical to understanding population-level patterns in animals. Here, we explore intraspecific variation in movement strategies of bald eagles (Haliaeetus leucocephalus) in the north Pacific, where there is high spatiotemporal resource variability. We tracked 28 bald eagles (five immature, 23 adult) using GPS transmitters between May 2010 and January 2016. Results: We found evidence of four movement strategies among bald eagles in southeastern Alaska and western Canada: breeding individuals that were largely sedentary and remained near nest sites year-round, non-breeding migratory individuals that made regular seasonal travel between northern summer and southern winter ranges, non-breeding localized individuals that displayed fidelity to foraging sites, and non-breeding nomadic individuals with irregular movement. On average, males traveled farther per day than females. Most nomadic individuals were immature, and all residential individuals (i.e. breeders and localized birds) were adults. Conclusions: Alternative movement strategies among north Pacific eagles are likely associated with the age and sex class, as well as breeding status, of an individual. Intraspecific variation in movement strategies within the population results in different space use patterns among contingents, which has important implications for conservation and management. © 2017 The Author(s).


Allen M.L.,University of California at Santa Cruz | Allen M.L.,University of Wisconsin - Madison | Wang Y.,University of California at Santa Cruz | Wang Y.,San Francisco Bay Bird Observatory | Wilmers C.C.,University of California at Santa Cruz
Canadian Field-Naturalist | Year: 2016

Communication is a central component of animal behaviour, yet communicative behaviours are poorly studied due to their complexity and varied functions. Pumas (Puma concolor) are wide-ranging, solitary felids that primarily use indirect cues (e.g., scent marking) for communication. Because these cryptic carnivores are rarely observed directly, little is known about their vocalizations in the wild. We recorded a variety of Puma vocalizations among females and family groups using motion-triggered video cameras and then attempted to understand the function of each vocalization. We found two categories of vocalizations: 1) attention-attracting (caterwauling and mewing), and 2) calls (contact, agitated, and alarm). Vocalizations to attract attention ranged across broad frequencies. Contact, agitated, and alarm calls are narrow-frequency vocalizations that varied in intensity and were used to communicate with nearby conspecifics. Vocal communication entails risk, and while some Puma vocalizations may provide benefits that outweigh their risk, others are structured to limit detection and risk. These observations highlight the importance of the structure of vocalizations used during different behaviours to understand their adaptive significance.


Kirkman K.P.,University of KwaZulu - Natal | Collins S.L.,University of New Mexico | Smith M.D.,Colorado State University | Knapp A.K.,Colorado State University | And 11 more authors.
Journal of Vegetation Science | Year: 2014

Question: Does fire frequency affect mesic grassland plant community structure and composition similarly in North America and South Africa? Location: Konza Prairie Biological Station (KNZ), Kansas, USA, and Ukulinga Research Farm (URF), KwaZulu-Natal, South Africa. Methods: Plant community structure and composition were compared among annually burned, unburned and intermediate treatments within two long-term fire frequency manipulation experiments in native grasslands in North America and South Africa using comparable methodology over a 5-yr period. Because fire may reduce soil nitrogen (N) availability and thus affect plant community structure, N additions were superimposed on the fire treatments as a means of assessing direct vs indirect mechanisms driving responses to fire. Results: The total number of species was higher at URF (183) than at KNZ (57). Overall divergence in plant community response to fire frequency occurred despite similar responses to nutrient additions. At KNZ, more frequent fire resulted in dominance by a few, tall, deep-rooted rhizomatous grasses (e.g. Andropogon gerardii). On unburned sites, shorter, more shade-tolerant species such as Poa pratensis increased in abundance, although A. gerardii remained dominant. Species richness increased with decreasing fire frequency at KNZ. At URF, frequent fire resulted in short, diverse grassland weakly dominated by a range of grass species, including Themeda triandra, Tristachya leucothrix and Hyparrhenia hirta. Decreasing fire frequency reduced species richness and resulted in dominance by a few, relatively tall caespitose grasses such as Aristida junciformis. There was a complete turnover of dominant species between annually burned and unburned treatments at URF, while at KNZ A. gerardii and Sorghastrum nutans occurred across the range of treatments. N addition reduced species richness in both sites. Conclusions: Different responses to fire frequency between KNZ and URF are likely linked to the dominant species and their characteristic traits, including height and method of clonal reproduction, with the rhizomatous growth form of A. gerardii dominating the North American grassland. South Africa does not have an equivalent grass species; instead, a range of tufted, non-rhizomatous species dominate across the fire frequency treatments at URF. Reductions in soil N due to frequent fire did not appear to be a common mechanism driving responses in community composition in these two grasslands. © 2013 International Association for Vegetation Science.


Harrison P.,Swingates | Sallaberry M.,University of Chile | Gaskin C.P.,400 Leigh Road | Baird K.A.,Forest and Bird | And 9 more authors.
Auk | Year: 2013

We describe a new species of storm-petrel, Oceanites pincoyae (Pincoya Storm-Petrel), from the Puerto Montt and Chacao channel area, Chile. The description is based on 1 specimen collected at sea in Seno Reloncavi on 19 February 2011 and 11 other individuals that were caught, examined, and released. The new taxon's foraging ecology and behavioral habits are unique among the southern Oceanitinae, including "mouse-runs" and repeated diving beneath the surface to retrieve food items. Its distinctive appearance includes bold white ulnar bars, extensive white panels to the underwing, and white to the lower belly and vent. Among species of Oceanites, it is unique in showing white outer vanes to the outer two pairs of rectrices. It further differs from all other storm-petrels in having a distinctive juvenile plumage. Morphometrically it is distinct from Oceanites gracilis gracilis (Elliot's Storm-Petrel) and smaller than O. oceananicus chilensis (the Fuegian form of Wilson's Storm-Petrel), having a shorter tarsus and longer middle toe. There also appear to be differences in the timing of breeding and molt between the new taxon and both O. o. chilensis and O. g. gracilis. We estimate the population size of the new species as ~3,000 individuals. Copyright © 2013 by The American Ornithologists' Union.


Carmi O.,San Francisco State University | Carmi O.,California Academy of Sciences | Witt C.C.,University of New Mexico | Jaramillo A.,San Francisco Bay Bird Observatory | And 2 more authors.
Molecular Phylogenetics and Evolution | Year: 2016

The Vermilion Flycatcher (Pyrocephalus rubinus) is a widespread species found in North and South America and the Galápagos. Its 12 recognized subspecies vary in degree of geographic isolation, phenotypic distinctness, and migratory status. Some authors suggest that Galápagos subspecies nanus and dubius constitute one or more separate species. Observational reports of distinct differences in song also suggest separate species status for the austral migrant subspecies rubinus. To evaluate geographical patterns of diversification and taxonomic limits within this species complex, we carried out a molecular phylogenetic analysis encompassing 10 subspecies and three outgroup taxa using mitochondrial (ND2, Cyt b) and nuclear loci (ODC introns 6 through 7, FGB intron 5). We used samples of preserved tissues from museum collections as well as toe pad samples from museum skins. Galápagos and continental clades were recovered as sister groups, with initial divergence at ~1 mya. Within the continental clade, North and South American populations were sister groups. Three geographically distinct clades were recovered within South America. We detected no genetic differences between two broadly intergrading North American subspecies, mexicanus and flammeus, suggesting they should not be recognized as separate taxa. Four western South American subspecies were also indistinguishable on the basis of loci that we sampled, but occur in a region with patchy habitat, and may represent recently isolated populations. The austral migrant subspecies, rubinus, comprised a monophyletic mitochondrial clade and had many unique nuclear DNA alleles. In combination with its distinct song, exclusive song recognition behavior, different phenology, and an isolated breeding range, our data suggests that this taxon represents a separate species from other continental populations. Mitochondrial and nuclear genetic data, morphology, and behavior suggest that Galápagos forms should be elevated to two full species corresponding to the two currently recognized subspecies, nanus and dubius. The population of dubius is presumed to be extinct, and thus would represent the first documented extinction of a Galápagos-endemic bird species. Two strongly supported mitochondrial clades divide Galápagos subspecies nanus in a geographic pattern that conflicts with previous hypotheses that were based on plumage color. Several populations of nanus have recently become extinct or are in serious decline. Urgent conservation measures should seek to preserve the deep mitochondrial DNA diversity within nanus, and further work should explore whether additional forms should be recognized within nanus. Ancestral states analysis based on our phylogeny revealed that the most recent common ancestor of extant Vermilion Flycatcher populations was migratory, and that migratory behavior was lost more often than gained within Pyrocephalus and close relatives, as has been shown to be the case within Tyrannidae as a whole. © 2016 Elsevier Inc.


Bluso-Demers J.D.,U.S. Geological Survey | Bluso-Demers J.D.,San Francisco Bay Bird Observatory | Ackerman J.T.,U.S. Geological Survey | Takekawa J.Y.,U.S. Geological Survey
Ardea | Year: 2010

In order to examine 24-hour colony attendance patterns by mated Forster's Terns Sterna forsteri in South San Francisco Bay, California, during incubation and chick-rearing stages, we radio-marked 10 individuals consisting of five pairs and recorded colony attendance using an automated data-logging receiver system. We calculated and analyzed five variables: the total attendance time by pairs and individuals, the duration of individual attendance bouts, and the duration both members of a pair either overlapped in colony attendance or were both absent from the colony. The percentage of time spent on the colony by at least one individual of a pair was highest during incubation and declined during chick rearing. Overall, male terns spent a greater proportion of time diurnally attending the colony than females. Females spent a greater proportion of time on colony at night, and without these nocturnal records, we would have reported overall female colony attendance rates as being much lower. Despite sex-specific differences in attendance rates, the length of attendance bouts did not differ between the sexes. Simultaneous colony attendance by both members of a pair was high at night, but during the day, pairs infrequently overlapped in their colony attendance and both members were frequently absent. Our datalogging system functioned well, and our data illustrates the importance of collecting 24-hour records when considering attendance rates.


Goodman R.E.,San Francisco State University | Lebuhn G.,San Francisco State University | Seavy N.E.,PRBO Conservation Science | Gardali T.,PRBO Conservation Science | Bluso-Demers J.D.,San Francisco Bay Bird Observatory
Global Change Biology | Year: 2012

There has been a growing interest in whether established ecogeographical patterns, such as Bergmann's rule, explain changes in animal morphology related to climate change. Bergmann's rule has often been used to predict that body size will decrease as the climate warms, but the predictions about how body size will change are critically dependent on the mechanistic explanation behind the rule. To investigate change in avian body size in western North America, we used two long-term banding data sets from central California, USA; the data spanned 40 years (1971-2010) at one site and 27 years (1983-2009) at the other. We found that wing length of birds captured at both sites has been steadily increasing at a rate of 0.024-0.084% per year. Although changes in body mass were not always significant, when they were, the trend was positive and the magnitudes of significant trends were similar to those for wing length (0.040-0.112% per year). There was no clear difference between the rates of change of long-distance vs. short-distance migrants or between birds that bred locally compared to those that bred to the north of the sites. Previous studies from other regions of the world have documented decreases in avian body size and have used Bergmann's rule and increases in mean temperature to explain these shifts. Because our results do not support this pattern, we propose that rather than responding to increasing mean temperatures, avian body size in central California may be influenced by changing climatic variability or changes in primary productivity. More information on regional variation in the rates of avian body size change will be needed to test these hypotheses. © 2011 Blackwell Publishing Ltd.


Spotswood E.N.,University of California at Berkeley | Goodman K.R.,University of California at Berkeley | Carlisle J.,Boise State University | Cormier R.L.,PRBO Conservation Science | And 4 more authors.
Methods in Ecology and Evolution | Year: 2012

The capture of birds using mist nets is a widely utilized technique for monitoring avian populations. While the method is assumed to be safe, very few studies have addressed how frequently injuries and mortalities occur and the associated risks have not been formally evaluated. We quantified the rates of mortality and injury at 22 banding organizations in the United States and Canada and used capture data from five organizations to determine what kinds of incidents occur most frequently. Analyses focused on passerines and near-passerines, but other groups were included. We evaluated whether body mass, age, sex, mist net mesh size, month and time of day or frequency of capture are related to the risk or type of incident. We also compared the recapture histories over time between birds that were injured and those that were never injured for 16 species. The average rate of injury was 0·59%, while mortality was 0·23%. Birds captured frequently were less at risk to incident. Body mass was positively correlated with incident and larger birds were at greater risk to predation, leg injuries, broken legs, internal bleeding and cuts, while smaller birds were more prone to stress, tangling-related injuries and wing strain. Rates of incident varied among species, with some at greater risk than others. We found no evidence for increased mortality over time of injured birds compared with uninjured birds. We provide the first comprehensive evaluation of the risks associated with mist netting. Our results indicate that (1) injury and mortality rates below one percent can be achieved during mist netting and (2) injured birds are likely to survive in comparable numbers to uninjured birds after release. While overall risks are low, this study identified vulnerable species and traits that may increase a bird's susceptibility to incident that should be considered in banding protocols aimed at minimizing injury and mortality. Projects using mist nets should monitor their performance and compare their results to those of other organizations. © 2011 The Authors. Methods in Ecology and Evolution © 2011 British Ecological Society.


PubMed | San Francisco State University, University of New Mexico and San Francisco Bay Bird Observatory
Type: | Journal: Molecular phylogenetics and evolution | Year: 2016

The Vermilion Flycatcher (Pyrocephalus rubinus) is a widespread species found in North and South America and the Galpagos. Its 12 recognized subspecies vary in degree of geographic isolation, phenotypic distinctness, and migratory status. Some authors suggest that Galpagos subspecies nanus and dubius constitute one or more separate species. Observational reports of distinct differences in song also suggest separate species status for the austral migrant subspecies rubinus. To evaluate geographical patterns of diversification and taxonomic limits within this species complex, we carried out a molecular phylogenetic analysis encompassing 10 subspecies and three outgroup taxa using mitochondrial (ND2, Cyt b) and nuclear loci (ODC introns 6 through 7, FGB intron 5). We used samples of preserved tissues from museum collections as well as toe pad samples from museum skins. Galpagos and continental clades were recovered as sister groups, with initial divergence at 1mya. Within the continental clade, North and South American populations were sister groups. Three geographically distinct clades were recovered within South America. We detected no genetic differences between two broadly intergrading North American subspecies, mexicanus and flammeus, suggesting they should not be recognized as separate taxa. Four western South American subspecies were also indistinguishable on the basis of loci that we sampled, but occur in a region with patchy habitat, and may represent recently isolated populations. The austral migrant subspecies, rubinus, comprised a monophyletic mitochondrial clade and had many unique nuclear DNA alleles. In combination with its distinct song, exclusive song recognition behavior, different phenology, and an isolated breeding range, our data suggests that this taxon represents a separate species from other continental populations. Mitochondrial and nuclear genetic data, morphology, and behavior suggest that Galpagos forms should be elevated to two full species corresponding to the two currently recognized subspecies, nanus and dubius. The population of dubius is presumed to be extinct, and thus would represent the first documented extinction of a Galpagos-endemic bird species. Two strongly supported mitochondrial clades divide Galpagos subspecies nanus in a geographic pattern that conflicts with previous hypotheses that were based on plumage color. Several populations of nanus have recently become extinct or are in serious decline. Urgent conservation measures should seek to preserve the deep mitochondrial DNA diversity within nanus, and further work should explore whether additional forms should be recognized within nanus. Ancestral states analysis based on our phylogeny revealed that the most recent common ancestor of extant Vermilion Flycatcher populations was migratory, and that migratory behavior was lost more often than gained within Pyrocephalus and close relatives, as has been shown to be the case within Tyrannidae as a whole.

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