Midwest Fish & Wildlife Conference 2016

AUTHORS: Sarah J. Baker*, Michael J. Dreslik, Christopher A. Phillips – Illinois Natural History Survey

ABSTRACT: Long-term monitoring projects are rare in ecological studies but provide invaluable information for conservation. We have been conducting annual population monitoring (including a combination of mark-recapture and telemetry) of eastern massasaugas Sistrurus catenatus at the last extant population in Illinois since 1999. Long-term mark-recapture has allowed us to document population crashes relating to stochastic flood events, but we also determined that population size is relatively stable over time. Such stability may indicate the population is near its carrying capacity, and an increase in habitat will be necessary to increase population size. Because of the temporal span of our data we can report detailed information regarding sources of mortality, reproduction, population genetics, and disease prevalence. The two greatest sources of mortality are automobiles and depredation. Telemetry studies are more likely to encounter depredation and observational studies are more likely to find automobile casualties. Our reproduction data indicate that mother size does not influence offspring number or size, and although some years neonate sex ratios appear to be skewed, overall sex ratios do not differ from 1:1. Evaluating population genetic parameters over a 10-year span revealed the loss of several rare alleles from the population, which could be a precursor to the loss of genetic diversity. Since the identification of an emerging fungal pathogen in 2008, continued disease monitoring has shown that its prevalence rate is relatively stable at 15-20%. Given the limitations of time and funding, long-term studies are not feasible for all populations. Therefore, existing long-term monitoring projects should be continued for comparison and extrapolation to other eastern massasauga populations, as well as other species with similar life histories.