Keyler, D.E. and J. Wilzbacher. 2002. Timber rattlesnake reproduction at XXX (2000 - 2002), Minnesota. Final report submitted to the Nongame Wildlife Program, Minnesota Department of Natural Resources. 10 pp.
XXX ecosystem appeared to support the largest timber rattlesnake population on state land in Minnesota a decade ago. Comprehensive field surveys conducted in southeastern state parks in Goodhue, Wabasha, Filmore, Winona, and Houston Counties during 1990-1991, and later surveys in 1998 in Olmsted County, yielded data, which supported this proclamation. Timber rattlesnake reproduction in XXX, from 1992 ?1997, had been previously confirmed by sporadic observation of neonates with maternal females, primarily at two sites; A1 and A2. Visual observation and recording the location of litters, number of litters, and the number of neonates per litter is an effective, noninvasive, method of monitoring timber rattlesnake reproduction. Timber rattlesnakes reproduce at approximately a 3-year cycle in northern latitudes, and formal monitoring of these XXX sites, over a time period which encompassed this 3-year female Timber Ratlesnake reproductive cycle, had not been previously attempted. Reproduction monitoring at A1 and A2 has now been completed for the consecutive three-year (2000 ? 2002) period with rookery and hibernacula at each site having been surveyed 2-3 times during the active seasons. Since neonates remain with their maternal females for 10 ? 14 days following birth and, given the three-year time-window study period, the number of surveys per site, specific timing of seasonal surveys, the confirmation of reproduction during the study period was probable. It was anticipated that optimal reproduction at the two study sites would have yielded annual observations of reproduction, while minimal reproduction would have resulted in only a single observation of reproduction at each site over the three active seasons. It was hoped that the overall viability of each den complex could be assessed. However, surveys made during favorable conditions resulted in no observations of Timber Rattlesnakes at A1 during any of the 2000-02 seasons. Concurrent surveys of A2 resulted in the observation of only four adult Crotalus horridus with the finding of only a single gravid female in August/September, 2002. Collectively, the results of the current survey support the conclusion that there has been a substantial decline in the Timber Rattlesnake population at A1 and A2 in XXX. Furthermore, recruitment of newborn snakes into the remaining population is minimal if not nil. Insults to Timber Rattlesnake habitat were observed at A1 each season during surveys, and they were the direct result of malicious human behavior. There is no doubt that this behavior has impacted the Timber Rattlesnake population. The negative findings of the current study demonstrate a profound loss that should serve as a driving force to increase conservation efforts for the Timber Rattlesnake in Minnesota. Protection of habitat, prevention of human intrusion and collecting, increased vigilance and surveillance, and appropriate land management should be of highest priority if the Timber Rattlesnake is to survive in the state of Minnesota.
Full document (46 KB)
Please note that all location information has been removed from this document to protect the timber rattlesnake populations