Surveying wintering warbler populations in Jamaica: point counts with and without broadcast vocalizations
Article Abstract:
The effectiveness of vocalization playbacks in the survey of warbler populations in Jamaica was evaluated. Playbacks resulted in the detection of more birds for both species studied. Older males in American redstart populations responded more strongly to the playbacks than yearling males or females, while no sex or age differences were detected in black-throated blue warblers. The time of day did not have any effect on the responsiveness of both species. The playbacks also attracted other species, with some being more visible during the playbacks with others being less detectable. Both species were highly territorial in distribution.
Publication Name: The Condor
Subject: Biological sciences
ISSN: 0010-5422
Year: 1992
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Biased detection of bird vocalizations affects comparisons of bird abundance among forested habitats
Article Abstract:
Vocalizations for nine bird species were broadcast to detect biases in detection of bird vocalizations among four forested habitats. All of the broadcasts were heard at 50 m. from the speaker but only 27% were detected at 100 m. away. Detection was greatest in white spruce forest and lowest in young aspen forest. It was also found that detection had negative relation to the minimum vocalization frequency, was greater for broadcasts from the canopy than for those from the shrub layer, and was greater for broadcasts before than after leaf formation. Biases among habitats moderately affected measures of habitat preference for birds.
Publication Name: The Condor
Subject: Biological sciences
ISSN: 0010-5422
Year: 1997
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Annual survival of breeding Cassin's auklets in the Queen Charlotte Islands,British Columbia
Article Abstract:
Survival data for a colony of Cassin's auklets in the Queen Charlotte islandswere calculated using the SURGE capture-recapture program and the regression method. Annual survival estimates were similar, 0.86 for the SURGE estimate and0.88 for the regression estimate, although the former is probably more accurate. Estimated life expectancy was computed at 7.6 years with regression and 8.8 years using the SURGE method. Both parameters are higher than those of ancient murrelets breeding in the same area.
Publication Name: The Condor
Subject: Biological sciences
ISSN: 0010-5422
Year: 1992
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