The Eastern Massasauga Rattlesnake: - U.S. Fish and Wildlife Service

population restrict overwintering activity to a 37 ha peatland within a larger wetland complex
and gravid females remain there from spring emergence to parturition as well. Mean 100%
minimum polygon activity range size for gravid females was 2.0 ha. Gravid females moved less
total distance (45.5 m), mean distance per day (7.1 m), and less often (45.5% of observations)
than male or nongravid females, who exhibited no differences in these measures. This reduction
in vagility associated with gravidity has been observed in other live-bearing snake species
(Brown et al. 1982, Reinert and Zappalorti 1988, Secor 1994, Viitanen 1967, Fitch and Shirer
1971). One hypothesis offered to explain this phenomenon is that gravid massasaugas are
selecting a location that maximizes thermoregulatory opportunity to reduce gestation time. King
(1997) also found differences between gravid females and males and nongravid females in
Wisconsin, although the differences between female groups were not very pronounced. In
Wisconsin, gravid females moved away from overwintering sites following emergence,
presumably to find suitable open-canopy basking sites that were not available near hibernacula.
Weatherhead and Prior (1992) found that female massasaugas had significantly smaller activity
ranges and other movement parameters than males at their site in Ontario, however, it was
unknown or unclear if any of the females were gravid. Reinert and Kodrich (1982) found no
differences between gravid female massasaugas and other classes in most movement parameters
in Pennsylvania, however, tracking periods were short and snakes were force-fed transmitters,
potentially inducing thermophily and reducing movement.
No significant differences were detected between male and nongravid female activity
ranges in Cicero Swamp (composite mean 100% activity range = 29 ha) (Johnson 2000). Males
and nongravid females did show a difference in range length (812 m for males, 1212 m for
females), which may be explained by the more straight-line, back and forth general movement
pattern from emergence to hibernation by the females or simply an artifact of the small sample
size. Males appear to wander more, perhaps related to the dual need of foraging and mate
location. Male massasaugas tracked for multiple years generally showed significant overlap in
yearly movements, however, core areas of activity varied. However, King (1997) found
significant differences between the sexes in several movement parameters and nongravid females
had significantly smaller activity ranges than males. Several other studies of snakes have
detected no differences between the sexes (e.g. Clark 1970, Plummer 1981, Michot 1981), while
some studies find clear differences (Madsen 1984, Slip and Shine 1988), with the females
generally possessing smaller activity ranges.
Only one study (King 1997) has included data on movement from radio-marked neonate
massasaugas. In his study, neonates made considerable movements, averaging similar distances
per move and per day as nongravid females. Total distance moved per season and home range
areas were similar to adult female massasaugas as well, although neonates were tracked for a
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