Great Lakes Biological Diversity

Activity Patterns and SPATIAL RESOURCE Selection of the Eastern Massasauga Rattlesnake in NORTHEASTERN INDIANA

EXECUTIVE SUMMARY

The Eastern Massasauga Rattlesnake, Sistrurus c. catenatus is being considered for federal listing as Threatened under the Endangered Species Act of 1973.  Management planning for this species would greatly benefit from ecological studies conducted at local scales and in habitats where their ecology is not yet well understood. Efforts have been increased to ascertain its ecological requirements and develop proper management approaches for it, especially in habitats not yet well understood.  Fens have received relatively little attention thus far in massasauga literature despite the fact that, in some regions, fens may support the largest populations of massasaugas (i.e. Indiana, Casebere 1997).

This report details findings from a four-year study (plus the current field season) of the massasauga at Cline Fen in northeastern Indiana. Patterns of movement, macrohabitat and microhabitat use were examined using radio telemetry. The results obtained for this site were also compared to findings by other researchers across the range of the subspecies.

Males exhibit the largest home ranges. One of the reasons for this is their tendency to make extensive moves in the summer to find females. Both males and nongravid females typically have two or three activity centers, and they may revisit these areas repeatedly over the activity season. Gravid females have the smallest home ranges, and usually only a single activity center. By late spring they establish themselves at a gestation site where they usually stay at until parturition in August. After giving birth, they show more extensive movements before returning to the hibernaculum. All classes of massasauga are usually, but not always, underground by mid-October.

All snakes prefer emergent vegetation for both their home range and their activity centers.  Of the emergent vegetation habitats Shore Line was selected the most often with respect to its availability. This is likely due to two reasons.  Most importantly, four gravid females used this habitat.  Within days of their emergence form hibernation these four females moved to locations along the lake shore where they established gestation sites and remained until early August.  Their use, along with the occasional use by others, likely led to the high ranking. In addition, the lake shore also only comprises a small amount of the study site (0.4%) and compositional analysis is susceptible to bias when habitat availability is low.  

Management efforts should focus on maintaining the early successional stages in the wetlands and their margins. Trees and shrubs should be discouraged, but complete removal of all shrub cover is inappropriate. While many commonly used management practices are compatible with massasaugas, timing considerations are very important for avoiding take. Many techniques are best used during the winter months, save water drawdowns, which could freeze hibernating snakes. Hibernacula are critical habitat- all known hibernacula should be aggressively protected.

EPA Home | Privacy and Security Notice | Contact Us