45 research outputs found

    WETLAND OCCUPANCY OF POND-BREEDING AMPHIBIANS IN YOSEMITE NATIONAL PARK, USA

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    We estimated wetland occupancy and population trends for three species of pond-breeding anurans in Yosemite National Park from 2007 – 2011. We used a double survey technique in which two observers independently surveyed each site on the same day. Double surveys allowed us to calculate detectability for the three most common anurans within the park: Rana sierrae, Anaxyrus canorus, and Pseudacris regilla. Annual estimates of detectability were generally high; mean detectability ranged from 73.7% + 0.6 (SE) for any life history stage of A. canorus to 86.7% + 0.7 for sites with P. regilla reproduction (eggs or larvae present). Detectability was most variable for Anaxyrus canorus, which ranged from 45.9% to 99.7%. The probability of occupancy for R. sierrae was highest in larger, low-elevation wetlands that lacked fish. Anaxyrus canorus were more common in shallow high-elevation ponds; their occurrence was minimally impacted by the presence of fish. Finally, occurrence of P. regilla was largely unrelated to wetland size and elevation, but like R. sierrae, they were less likely to occupy sites with fish. Occupancy showed no trend over the five years of our study for R. sierrae or A. canorus when considering either sites with any life stage or only sites with reproduction. However, P. regilla showed a modest downward trend for sites with any life stage and sites with reproduction. Our results for R. sierrae run counter to expectations given recent concern about the decline of this species, while our findings for P. regilla raise concerns for this widespread and generally common species

    Quantitative Evidence for the Effects of Multiple Drivers on Continental-Scale Amphibian Declines

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    Since amphibian declines were first proposed as a global phenomenon over a quarter century ago, the conservation community has made little progress in halting or reversing these trends. The early search for a “smoking gun” was replaced with the expectation that declines are caused by multiple drivers. While field observations and experiments have identified factors leading to increased local extinction risk, evidence for effects of these drivers is lacking at large spatial scales. Here, we use observations of 389 time-series of 83 species and complexes from 61 study areas across North America to test the effects of 4 of the major hypothesized drivers of declines. While we find that local amphibian populations are being lost from metapopulations at an average rate of 3.79% per year, these declines are not related to any particular threat at the continental scale; likewise the effect of each stressor is variable at regional scales. This result - that exposure to threats varies spatially, and populations vary in their response - provides little generality in the development of conservation strategies. Greater emphasis on local solutions to this globally shared phenomenon is needed

    Quantitative Evidence for the Effects of Multiple Drivers on Continental-Scale Amphibian Declines

    Get PDF
    Since amphibian declines were first proposed as a global phenomenon over a quarter century ago, the conservation community has made little progress in halting or reversing these trends. The early search for a “smoking gun” was replaced with the expectation that declines are caused by multiple drivers. While field observations and experiments have identified factors leading to increased local extinction risk, evidence for effects of these drivers is lacking at large spatial scales. Here, we use observations of 389 time-series of 83 species and complexes from 61 study areas across North America to test the effects of 4 of the major hypothesized drivers of declines. While we find that local amphibian populations are being lost from metapopulations at an average rate of 3.79% per year, these declines are not related to any particular threat at the continental scale; likewise the effect of each stressor is variable at regional scales. This result - that exposure to threats varies spatially, and populations vary in their response - provides little generality in the development of conservation strategies. Greater emphasis on local solutions to this globally shared phenomenon is needed

    Status and Distribution of Ants in the Crater District of Haleakala National Park

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    The Crater District of Haleakala National Park was surveyed for ants. Three species were found. Argentine ants (Iridomyrmex humilis) occurred only within I km of the park headquarters and the nearby research facility. Hypoponera opaciceps was found in small numbers throughout the Crater District. Cardiocondyla emeryi was present only at the head of Kaupo Gap. Possible impacts of these ant species on the endemic, flightless insects of the park are discussed

    California Myotis search call

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    AnimaliaCraniataMammaliaChiropteraVespertilionidaeMyotisCompressed from .wav format into .mp3 delivery formatSearch phase calls of a California MyotisSearch phase calls. These calls are used to detect what is present in the vicinity of a bat, be it food or obstacles that the bat must navigate around. These calls are often species specific and can thus be used to identify the type of bat making the call. Source: http://www.werc.usgs.gov/bats/searchphasecall.html.This recording was made by a high frequency bat detector. The pitch (frequency) for this recording has been lowered by a factor of 16 so the calls fall within the range of human hearing

    Western Mastiff Bat search call

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    AnimaliaCraniataMammaliaChiropteraMolossidaeEumopsCompressed from .wav format into .mp3 delivery formatSearch phase call of a Western Mastiff BatSearch phase calls. These calls are used to detect what is present in the vicinity of a bat, be it food or obstacles that the bat must navigate around. These calls are often species specific and can thus be used to identify the type of bat making the call. Source: http://www.werc.usgs.gov/bats/searchphasecall.html. This recording was made by a high frequency bat detecto

    Big Brown Bat search call

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    AnimaliaCraniataMammaliaChiropteraVespertilionidaeEptesicusCompressed from .wav format into .mp3 delivery formatSearch phase calls of a Big Brown BatSearch phase calls. These calls are used to detect what is present in the vicinity of a bat, be it food or obstacles that the bat must navigate around. These calls are often species specific and can thus be used to identify the type of bat making the call. Source: http://www.werc.usgs.gov/bats/searchphasecall.html. This recording was made by a high frequency bat detector. The pitch (frequency) for this recording has been lowered by a factor of 16 so the calls fall within the range of human hearing

    Silver-haired Bat search call

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    AnimaliaCraniataMammaliaChiropteraVespertilionidaeLasionycterisCompressed from .wav format into .mp3 delivery formatSearch phase call of a Silver-haired BatSearch phase calls. These calls are used to detect what is present in the vicinity of a bat, be it food or obstacles that the bat must navigate around. These calls are often species specific and can thus be used to identify the type of bat making the call. Source: http://www.werc.usgs.gov/bats/searchphasecall.html. This recording was made by a high frequency bat detector. The pitch (frequency) for this recording has been lowered by a factor of 16 so the calls fall within the range of human hearing
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