A Model to Inform Management Actions as a Response to Chytridiomycosis-Associated Decline
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Decision-analytic models provide forecasts of how systems of interest will respond to management. These models can be parameterized using empirical data, but sometimes require information elicited from experts. When evaluating the effects of disease in species translocation programs, expert judgment is likely to play a role because complete empirical information will rarely be available. We illustrate development of a decision-analytic model built to inform decision-making regarding translocations and other management actions for the boreal toad (Anaxyrus boreas boreas), a species with declines linked to chytridiomycosis caused by Batrachochytrium dendrobatidis (Bd). Using the model, we explored the management implications of major uncertainties in this system, including whether there is a genetic basis for resistance to pathogenic infection by Bd, how translocation can best be implemented, and the effectiveness of efforts to reduce the spread of Bd. Our modeling exercise suggested that while selection for resistance to pathogenic infection by Bd could increase numbers of sites occupied by toads, and translocations could increase the rate of toad recovery, efforts to reduce the spread of Bd may have little effect. We emphasize the need to continue developing and parameterizing models necessary to assess management actions for combating chytridiomycosis-associated declines.
keywordsAnaxyrus boreas boreas boreal toads decision analysis disease resistance evolutionary rescue translocation
We thank the Zoological Society of London, and especially JG Ewen, for inviting SJC to take part in the symposium on health and disease in translocated wild animals that prompted development of this model. The useful input of JG Ewen, S Canessa, and JD Nichols contributed to the symposium presentation and the evolution of this modeling effort. We thank the members of the Southern Rocky Mountain Boreal Toad Conservation Team, especially H Crockett, for their enthusiastic participation in the SRM boreal toad conservation planning effort. We also appreciate the contribution of RD Scherer, who provided us with the model output necessary to include CMR-based toad survival in our model. Finally, 2 anonymous reviewers and AW Sainsbury made useful comments on the original manuscript. This is contribution number 527 of the USGS Amphibian Research and Monitoring Initiative (ARMI).
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