Conservation Science

Massasaugas utilize low-lying, poorly drained open habitats in the spring, fall and winter. They rely on crayfish burrows and other fissures to access ground water that remains unfrozen throughout the winter for hibernation. This habitat allows snakes to find refuge from the freezing Pennsylvania winters and retreat from predators in the spring and fall. After emerging from hibernation in April, the massasauga begins feeding on small rodents and sunning in lowland areas for about a month.

In late spring and summer, they move upland to nearby drier fields, prairies or meadows. During this time, males and non-pregnant females will spend the summer foraging. Breeding takes place in August and September. Pregnant females will choose sparsely vegetated dry areas to bask until they give birth to their young in August or early September. Females reach breeding age at four years and give birth to an average of six or seven young every other year. The average seasonal home range for the massasauga in Western Pennsylvania is 3.8 acres.

Many species, such as the massasauga, are uniquely important as indicators of environmental quality and function as “environmental monitors.” They also control the rodent population, thereby controlling rodent-carried diseases. Breakthroughs in the medical field have even resulted in medications for hypertension and diabetes from rattlesnake venom.

There are many direct and indirect benefits to conserving this species in Pennsylvania. Yet these docile and ecologically important creatures are in great jeopardy. Without immediate conservation of critical habitat for the massasauga, remaining populations may be lost in the near future.

The dramatic decline of the eastern massasauga is alarming. Since the early 1900s damming, road building, surface mining and urbanization have destroyed large amounts of Pennsylvania’s massasauga habitat. Since the massasauga requires open space, the habitat that remains is threatened by becoming overgrown by trees and shrubs.

Managing Massasauga Habitat

In general, massasauga habitat can be established and managed using a variety of practices, including the following:

• Brush clearing
• Carefully timed seasonal mowing
• Establishing/seeding prairie grasses, wildflowers and other native plants
• Prescribed burning
• Selective use of herbicides

Most of the management activities should occur during the massasauga’s hibernation period between November and March when the ground is frozen. Reclaimed massasauga habitat must be maintained periodically to keep forest encroachment in check. This may require management as often as every few years to as rarely as every 20 years, depending on the site.

Inventory (2003-2005)

The Conservancy and the Pennsylvania Natural Heritage Program investigated the presence of the eastern massasauga at 63 locations in Western Pennsylvania where the snake was historically known to reside. Over the past century, the eastern massasauga has declined from 19 populations in six counties to only four isolated populations in Butler and Venango counties.

The results of the two-year inventory found only four locations with known massasauga populations. Nineteen locations provided doubtful evidence for the support of populations and 38 were considered extirpated. Two locations were believed to have been reported erroneously. The massasauga’s decline happened despite identification of contributing factors and state listing as an endangered species. Habitat loss, once caused most prominently by the destruction of wetlands, is now primarily caused by forest succession and is the main factor for modern-day population declines. If this habitat loss remains unchecked, it will likely result in the extirpation of the remaining populations.

Radio Telemetry (2005-2006)

As WPC considered ways to help conserve this species, an important piece of information was missing: the way that massasaugas use the habitat and the role that temperature plays in movement and hibernation.

To better understand the ecology of these animals within specific locations in Pennsylvania, WPC undertook a study of movement of individual snakes over a two-year period. In all, 51 free-ranging individuals – 17 gravid (pregnant) females, 7 non-gravid females, 12 males and 15 juveniles – were equipped with temperature sensitive radio transmitters and monitored every 48 hours.

Through this study, WPC and PNHP concluded that adult massasaugas in Pennsylvania had a mean home range of 3.8 acres, and mean total distance moved over a season of 2,465 feet. Gravid females had smaller home ranges and movement parameters than males, non-gravid females and postpartum females. When tracked over the entire activity season, there was no significant difference in the home ranges or movements of snakes of different sexes or reproductive conditions.

We were also able to determine the massasauga’s seasonal movements and habitat preferences. Seasonal movements were characterized by a general tendency to remain in or near hibernacula in the spring. In the summer, the snake expanded its range and movement to surrounding areas of drier, upland habitat dominated by forbs and open canopy. In autumn, massasauga showed a gradual return to the hibernacula, with a preference for areas with forbs and open canopy. Gravid females showed a particular preference for dry areas of very low vegetation, often in proximity to shrubs.

Fields of forbs and low-growing grasses with an open canopy and spotty distribution of woody shrubs characterize the habitat of the massasauga in Pennsylvania. Habitat is consistently found in proximity to wetland soils. Snakes of different age and fitness respond to subtle differences in micro-habitat that meet their individual needs and this is true throughout their life histories.