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White-nose syndrome is likely to extirpate the endangered Indiana bat over large parts of its range

Thogmartin, W.E., Sanders-Reed, C.A., Szymanski, J.A., McKann, P.C., Pruitt, L., King, R.A., Runge, M.C., Russell, R.E., 2013, White-nose syndrome is likely to extirpate the endangered Indiana bat over large parts of its range. Biological Conservation, v160, p 162-172. http://dx.doi.org/10.1016/j.biocon.2013.01.010

Abstract

 White-nose syndrome, a novel fungal pathogen spreading quickly through cave-hibernating bat species in east and central North America, is responsible for killing millions of bats. We developed a stochastic, stage-based population model to forecast the population dynamics of the endangered Indiana bat (Myotis sodalis) subject to white-nose syndrome. Our population model explicitly incorporated environmentally imposed annual variability in survival and reproductive rates and demographics to chasticity in predictions of extinction. With observed rates of disease spread, >90% of wintering populations were predicted to experience white-nose syndrome within 20 years, causing the proportion of populations at the quasi- extinction threshold of less than 250 females to increase by 33.9% over 50 years. At the species’ lowest median population level, ca. year 2022, we predicted 13.7% of the initial population to remain, totaling 28,958 females(95%CI=13,330;92,335).By2022,only 12 of the initial 52 wintering populations were expected to possess wintering populations of >250 females. If the species can acquire immunity to the disease, we predict 3.7% of wintering populations to be above 250 females after 50 years (year 2057)after a 69%decline in abundance (from 210,741 to 64,768 [95%CI=49,386;85,360] females). At the nadir of projections, we predicted regional quasi-extirpation of wintering populations in 2 of 4 Recovery Units while in a third region, where the species is currently most abundant, >95% of the wintering populations were predicted to be below 250 females. Our modeling suggests white-nose syndrome is capable of bringing about severe numerical reduction in population size and local and regional extirpation of the Indiana bat.

Keywords

Bats Demographic model Endangered species Extinction risk Fungus Geomyces destructans Myotis sodalis WNS