Using occupancy models to understand the distribution of an amphibian pathogen, Batrachochytrium dendrobatidis

Publication Type:

Journal Article

Authors:

Adams, Michael J.; Chelgren, Nathan D.; Reinitz, David; Cole, Rebecca A.; Rachowicz, Lara J.; Galvan, Stephanie; McCreary, Brome; Pearl, Christopher A.; Bailey, Larissa L.; Bettaso, Jamie; Bull, Evelyn L.; Leu, Matthias

Source:

Ecological Applications, Ecological Society of America, Volume 20, Issue 1, p.289–302 (2010)

Call Number:

A10ADA01IDUS

Keywords:

American bullfrog, Anaxyrus boreas, Batrachochytrium dendrobatidis, Bufo boreas, chytrid fungus, Columbia Spotted Frog, Lithobates catesbeianus, Rana luteiventris, Western Toad

Abstract:

Batrachochytrium dendrobatidis is a fungal pathogen that is receiving attention around the world for its role in amphibian declines. Study of its occurrence patterns is hampered by false negatives: the failure to detect the pathogen when it is present. Occupancy models are a useful but currently underutilized tool for analyzing detection data when the probability of detecting a species is <1. The authors use occupancy models to evaluate hypotheses concerning the occurrence and prevalence of B. dendrobatidis and discuss how this application differs from a conventional occupancy approach. They found that the probability of detecting the pathogen, conditional on presence of the pathogen in the anuran population, was related to amphibian development stage, day of the year, elevation, and human activities. Batrachochytrium dendrobatidis was found throughout the study area but was only estimated to occur in 53.4% of 78 populations of native amphibians and 66.4% of 40 populations of nonnative Rana catesbeiana [Lithobates catesbeianus] tested. The authors found little evidence to support any spatial hypotheses concerning the probability that the pathogen occurs in a population, but did find evidence of some taxonomic variation. They discuss the interpretation of occupancy model parameters, when, unlike a conventional occupancy application, the number of potential samples or observations is finite.