The eastern massasauga rattlesnake (Sistrurus catenatus catenatus) is a federally Threatened species due to factors that include degradation and fragmentation of habitat and corresponding population declines throughout the species range. Further, a fungal pathogen (Ophidiomyces ophiodiicola) which affects snake species across North America is a potential threat to massasauga populations. The ability to identify and assess suitability of current and potential habitats, to effectively locate massasaugas, and to determine population demographic rates, are warranted for conservation of the species. In 2015 and 2016, we identified 27 20-ha study sites of varying habitat quality throughout southern Michigan where massasaugas were known to occur historically. At these sites, we applied and validated a habitat suitability index (HSI) model by quantifying the habitat attributes defined by the model (% live and dead herbaceous cover, number and DBH of trees and shrubs >3 m in height, % area in early successional deciduous upland and wetland). Habitat suitability index scores across all sites ranged from 0.21 to 0.95. We used HSI scores to predict the likelihood that a given site is occupied by massasaugas (i.e., occupancy probability). For sites approaching maximum suitability (HSI = 1), predicted occupancy was > 0.5, while for poor suitability sites (HSI scores approaching 0) predicted occupancy was < 0.2. We used resource selection probability function analysis to quantify habitat use versus availability and found a positive relationship between probability of use and % live and dead herbaceous cover, and a negative relationship between probability of use and number of stems and DBH of trees >3 m in height.To aid researchers and managers in successfully detecting massasaugas in occupied habitat we developed and tested a visual encounter survey method. We quantified detection probability for massasaugas using this method and determined factors important in influencing detection probability (i.e., environmental conditions, surveyor conditions) at 4 study sites. In 2016, we completed 54 detection surveys with 5 surveyors; we detected ≥1 massasauga at 11 surveys. Our null detection probability was 0.31. We found that time spent searching and minimum air temperature were the most important correlates of detection probability of the variables we measured: detection probability approached 1.00 as searcher time exceeded 90 minutes and approached 0.80 on cooler mornings (down to 12.8°C). At six of our 27 study sites, we obtained sufficient massasauga locations (i.e., ≥30) via radio telemetry or random encounters to estimate survivorship for the study region. In total, we telemetered 22 adults, 6 juveniles, and 10 neonates using both surgical implantation of transmitters and external attachment. For the 137-day study period during the active season, adult massasauga survivorship estimated using the Mayfield method was 0.767 (SE = 0.016). For juveniles and neonates, apparent survivorship was 0.65. Radiograph imagery or palpation of 17 gravid females resulted in embryo counts ranging from 5 to 18; litter counts in the field ranged from 1 to 15 (n = 6). We radio tracked neonate massasaugas from 2 to 26 days and found that they moved up to 551.2 m from the gestation site. Snake fungal disease is a potential threat to massasauga populations and has been found in Michigan. To determine the presence of snake fungal disease at our study sites, we collected skin swab samples of all captured massasaugas. Out of 24 and 46 samples collected in 2015 and 2016, respectively, 3 individuals at good and optimal suitability sites tested positive for the pathogen in two counties where the pathogen had not yet been documented.
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