Timber Rattlesnake

Timber Rattlesnake

The timber rattlesnake (crotalus horridus) plays an important predator role in deciduous forests. One of New England’s few venomous snake species, they generally prefer more thickly wooded habitats where the closed forest canopy keeps air temperatures cooler. In the summer, gravid (pregnant) females can be found on open, rocky ledges where temperatures are higher. 

These rattlers eat (and therefore manage populations of) small mammals, birds, and sometimes lizards, frogs and other snakes. In turn, theses snakes provide a source of food for hawks, bobcats, coyotes, and foxes, while black racers and king snakes will prey upon young timber rattlers. Human fear, however, is the greatest threat to the timber rattlesnake. Timber rattlesnake territories have declined from 31 states to 27, and populations have been completely extirpated from Maine, Rhode Island, central New Hampshire, most of Vermont, Long Island, and eastern and northern Ohio) and probably from Michigan and possibly from Delaware.

Currently, nine states (including all New England states) and the Province of Ontario offer the timber rattlesnake some form of protection, listing it as threatened or endangered, or having a restricted or no-take policy. Fifteen other states have general regulations that protect some or all herpetofauna [the class of animals that includes amphibians and reptiles] and therefore the timber rattlesnake by default.

This serious concern is multiplied by the fact that since 2009, timber rattlesnakes from separate populations in eastern, central and western Massachusetts have been found to have significant disease identified as fungal dermatitis.  This disease has been previously documented by scientists as a cause of morbidity and mortality in both captive and free-ranging viperidae [venomous viper taxon] snakes.

Questions? Contact Louis Perrotti, director of conservation programs at Lperrotti@rwpzoo.org or call (401) 785-3510 ext. 335.

The Recovery Program

In 2011, RWP Zoo staff members joined New England biologists and conservationists in a collaborative regional effort created to save the remaining timber rattlesnake populations. They believe that a protected genetic reservoir from the most threatened populations in the northeast should be established in captivity until a solid conservation initiative develops; this involves head-starting and possibly captive reproduction in the future as well as addressing the fungal dermatitis problem.

In 2012, Disney’s Animal Kingdom provided $6,000 for a pilot program to help develop the protocols that would be needed for a larger-scale project. In early 2013, the collaborators received an $81,300 Northeast Regional Conservation Needs Grant for the assessment and evaluation of the prevalence of the fungal dermatitis in New England timber rattlesnake populations.

Wildlife disease studies in natural populations are becoming increasingly important in aiding wildlife management and conservation. Many infectious agents pose a threat to wildlife populations, and there is a growing body of literature documenting disease outbreaks which are effecting populations and even extirpated species. The grant monies will undertake a comprehensive evaluation and a baseline health assessment of multiple New England populations as well as to provide scientific support for future policy and wildlife management decisions for this species. The study will present evidence of the extent of fungal dermatitis among multiple rattlesnake populations, and evaluate potential underlying stressors or factors predisposing the species to fungal disease.

The partners will use the information to try to determine whether the fungal disease seen is a primary pathogen or a secondary opportunistic invader. They also will look for insight as to whether these are isolated cases or if they are indicative of wider health concerns within timber rattlesnake populations. Additionally, they will produce a geographical map of fungal infections identified in New England populations. Researchers will evaluate the presence of heavy metals and toxins as potential immune system stressors thus utilizing the timber rattlesnake as an indicator of potential environmental pollutants as well as overall ecosystem health.

In 2014, the RWP Zoo veterinary and conservation departments in partnership with state biologists finished the two-year federally-funded study doing research to learn more about the fungus, and determine how prevalent the fungus is in New England Populations. This work was featured on “Ocean Mysteries” with Jeff Corwin in November 2014.

Currently, RWP Zoo staff members conduct biopsies and blood work for the project for the on-going fungal disease study and work with adult snakes and neonates [newborns] for captive breeding and head starting. All the head started individuals will be used to augment existing populations in MA and to create new populations within its historic range in the state of MA.