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An evaluation of weather and disease as causes of decline in two populations of boreal toads

Ecological Applications

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Abstract

Two populations of boreal toads (Bufo boreas) experienced drastic declines in abundance in the late 1990s. Evidence supported the hypothesis of disease (the chytrid fungus, Batrachochytrium dendrobatidis) as the cause of these declines, but other hypotheses had not been evaluated. We used an 11-year capture-recapture data set to evaluate weather and disease as causes of these declines. We developed sets of mathematical models that reflected hypothesized relationships between several weather variables and annual survival rates of adult males in these populations. In addition, models that reflected the possibility that the declines were caused by an introduced fungus were developed. All models were fit to the data and were evaluated using a model selection criterion (QAICc). Our analysis provided strong support for the hypothesis of an introduced fungus and little support for the hypothesis that weather conditions caused the declines. Our results also suggest a strong, negative 'marking effect' on survival rates of boreal toads. Model-averaged estimates of survival rate are presented.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
An evaluation of weather and disease as causes of decline in two populations of boreal toads
Series title:
Ecological Applications
Volume
15
Issue:
6
Year Published:
2005
Language:
English
Contributing office(s):
Fort Collins Science Center
Description:
p. 2150-2160
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
2150
Last page:
2160
Number of Pages:
11