The Experts below are selected from a list of 984 Experts worldwide ranked by ideXlab platform
David N Bonter - One of the best experts on this subject based on the ideXlab platform.
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the sound of danger threat sensitivity to predator vocalizations alarm calls and novelty in Gulls
PLOS ONE, 2013Co-Authors: Sarah Maclean, David N BonterAbstract:The threat sensitivity hypothesis predicts that organisms will evaluate the relative danger of and respond differentially to varying degrees of predation threat. Doing so allows potential prey to balance the costs and benefits of anti-predator behaviors. Threat sensitivity has undergone limited testing in the auditory modality, and the relative threat level of auditory cues from different sources is difficult to infer across populations when variables such as background risk and experience are not properly controlled. We experimentally exposed a single population of two sympatric Gull species to auditory stimuli representing a range of potential threats in order to compare the relative threat of heterospecific alarm calls, conspecific alarms calls, predator vocalizations, and novel auditory cues. Gulls were able to discriminate among a diverse set of threat indicators and respond in a graded manner commensurate with the level of threat. Vocalizations of two potential predators, the human voice and bald eagle call, differed in their threat level compared to each other and to alarm calls. Conspecific alarm calls were more threatening than heterospecfic alarm calls to the larger Great Black-Backed Gull, but the smaller herring Gull weighed both equally. A novel cue elicited a response intermediate between known threats and a known non-threat in herring Gulls, but not Great Black-Backed Gulls. Our results show that the relative threat level of auditory cues from different sources is highly species-dependent, and that caution should be exercised when comparing graded and threshold threat sensitive responses.
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Intensity of response to auditory threats.
2013Co-Authors: Sarah A. Maclean, David N BonterAbstract:Intensity of response by (a) herring Gulls and (b) Great Black-Backed Gulls to various auditory stimuli and a physical approach by a human. Raw means and standard errors are reported, with different letters indicating statistically significant differences among stimuli, based on log odds ratios. SOSP = song sparrow, WESJ = western scrub-jay, HERG = herring Gull, GBBG = Great Black-Backed Gull, BAEA = bald eagle.
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Duration of response to auditory threats.
2013Co-Authors: Sarah A. Maclean, David N BonterAbstract:Duration of response by (a) herring Gulls and (b) Great Black-Backed Gulls to various auditory stimuli and a physical approach by a human. Because the majority of responses fell in lower time intervals, latencies above 15 sec have been binned to aid visualization. SOSP = song sparrow, WESJ = western scrub-jay, HERG = herring Gull, GBBG = Great Black-Backed Gull, BAEA = bald eagle.
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The sound of danger: threat sensitivity to predator vocalizations, alarm calls, and novelty in Gulls
2013Co-Authors: Sarah A. Maclean, David N BonterAbstract:The threat sensitivity hypothesis predicts that organisms will evaluate the relative danger of and respond differentially to varying degrees of predation threat. Doing so allows potential prey to balance the costs and benefits of anti-predator behaviors. Threat sensitivity has undergone limited testing in the auditory modality, and the relative threat level of auditory cues from different sources is difficult to infer across populations when variables such as background risk and experience are not properly controlled. We experimentally exposed a single population of two sympatric Gull species to auditory stimuli representing a range of potential threats in order to compare the relative threat of heterospecific alarm calls, conspecific alarms calls, predator vocalizations, and novel auditory cues. Gulls were able to discriminate among a diverse set of threat indicators and respond in a graded manner commensurate with the level of threat. Vocalizations of two potential predators, the human voice and bald eagle call, differed in their threat level compared to each other and to alarm calls. Conspecific alarm calls were more threatening than heterospecfic alarm calls to the larger Great Black-Backed Gull, but the smaller herring Gull weighed both equally. A novel cue elicited a response intermediate between known threats and a known non-threat in herring Gulls, but not Great Black-Backed Gulls. Our results show that the relative threat level of auditory cues from different sources is highly species-dependent, and that caution should be exercised when comparing graded and threshol
Susan Elbin - One of the best experts on this subject based on the ideXlab platform.
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contaminant levels in herring larus argentatus and Great black backed Gull larus marinus eggs from colonies in the new york harbor complex between 2012 and 2013
Ecotoxicology, 2015Co-Authors: Joanna Burger, Susan ElbinAbstract:Birds living in coastal areas are exposed to severe storms and tidal flooding during the nesting season, but also to contaminants that move up the food chain from the water column and sediment to their prey items. We examine metals in Herring Gull (Larus argentatus) and Great Black-Backed Gull (Larus marinus) eggs collected from the New York/New Jersey harbor estuary in 2012 and in 2013 to determine if there were significant yearly differences in metal levels. We test the null hypothesis that there were no significant yearly differences in metal levels. We investigate whether there were consistent differences in metals from 2012 to 2013 that might suggest a storm-related effect because Superstorm Sandy landed in New Jersey in October 2012 with high winds and extensive flooding, and view this research as exploratory. Except for arsenic, there were significant inter-year variations in the mean levels for all colonies combined for Herring Gull, and for lead, mercury and selenium for Great Black-Backed Gulls. All metal levels in 2013 were less than in 2012, except for lead. These differences were present for individual colonies as well. Metal levels varied significantly among islands for Herring Gulls in both years (except for cadmium in 2013). No one colony had the highest levels of all metals for Herring Gulls. A long term data set on mercury levels in Herring Gulls indicated that the differences between 2012 and 2013 were Greater than usual. Several different factors could account for these differences, and these are discussed.
Eric W. M. Stienen - One of the best experts on this subject based on the ideXlab platform.
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Seabird avoidance and attraction at an offshore wind farm in the Belgian part of the North Sea
Hydrobiologia, 2015Co-Authors: Nicolas Vanermen, Thierry Onkelinx, Wouter Courtens, Marc Van De Walle, Hilbran Verstraete, Eric W. M. StienenAbstract:Through before–after control-impact designed ship-based seabird surveys, seabird displacement occurring after the installation of an offshore wind farm at the Belgian Bligh Bank in 2010 was studied. Results demonstrate that northern gannet ( Morus bassanus ), common guillemot ( Uria aalge ) and razorbill ( Alca torda ) avoided the wind farm area, and decreased in abundance with 85, 71 and 64%, respectively. Lesser Black-Backed Gull ( Larus fuscus ) and herring Gull ( Larus argentatus ) were attracted to the wind farm, and their numbers increased by a factor 5.3 and 9.5. Other Gull species too were found to frequent the turbine-built area, most notably common Gull ( Larus canus ), black-legged kittiwake ( Rissa tridactyla ) and Great Black-Backed Gull ( Larus marinus ). The ecological incentives behind the observed attraction effects are still poorly understood, but on top of the increase in roosting possibilities it is plausible that offshore wind farms offer enhanced feeding opportunities. Importantly, attraction of seabirds to offshore wind farms implies an increased collision risk.
Sarah Maclean - One of the best experts on this subject based on the ideXlab platform.
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the sound of danger threat sensitivity to predator vocalizations alarm calls and novelty in Gulls
PLOS ONE, 2013Co-Authors: Sarah Maclean, David N BonterAbstract:The threat sensitivity hypothesis predicts that organisms will evaluate the relative danger of and respond differentially to varying degrees of predation threat. Doing so allows potential prey to balance the costs and benefits of anti-predator behaviors. Threat sensitivity has undergone limited testing in the auditory modality, and the relative threat level of auditory cues from different sources is difficult to infer across populations when variables such as background risk and experience are not properly controlled. We experimentally exposed a single population of two sympatric Gull species to auditory stimuli representing a range of potential threats in order to compare the relative threat of heterospecific alarm calls, conspecific alarms calls, predator vocalizations, and novel auditory cues. Gulls were able to discriminate among a diverse set of threat indicators and respond in a graded manner commensurate with the level of threat. Vocalizations of two potential predators, the human voice and bald eagle call, differed in their threat level compared to each other and to alarm calls. Conspecific alarm calls were more threatening than heterospecfic alarm calls to the larger Great Black-Backed Gull, but the smaller herring Gull weighed both equally. A novel cue elicited a response intermediate between known threats and a known non-threat in herring Gulls, but not Great Black-Backed Gulls. Our results show that the relative threat level of auditory cues from different sources is highly species-dependent, and that caution should be exercised when comparing graded and threshold threat sensitive responses.
Morten Helberg - One of the best experts on this subject based on the ideXlab platform.
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relationships between reproductive performance and organochlorine contaminants in Great black backed Gulls larus marinus
Environmental Pollution, 2005Co-Authors: Morten Helberg, Jan Ove Bustnes, Kjell Einar Erikstad, Kai Ove Kristiansen, Janneche Utne SkaareAbstract:Abstract The Great Black-Backed Gull Larus marinus is a top predator in subarctic and temperate marine ecosystems, and the aim of this study was to investigate if organochlorines (OCs) were related to reproductive performance in this species at the subarctic parts of the Norwegian Coast. We measured blood levels of various OCs in 53 breeding birds. The OC levels were relatively low compared to levels found in nearby arctic areas. In females, however, there was a significant positive relationship between blood concentrations of OCs, especially hexachlorobenzene (HCB) and, p , p ′-dichlorodiphenyldichloroethylene (DDE), and egg laying date, and a positive relationship between the probability of nest predation and blood concentration of β-hexachlorocyclohexane (β-HCH), oxychlordane, and DDE. In females with high levels of OCs, especially persistent polychlorinated biphenyls (PCBs), there was also a decline in egg volume as egg laying progressed; i.e. the second and third laid egg were relatively smaller, compared to females with low OC levels. No relationships between reproductive parameters and OC levels were found in males.
