Snakes are important predators of rodents and other pests in natural systems and are an integral part of functional ecological systems. In order to document and monitor the snake species on Jekyll Island we began a mark-recapture program in the summer of 2011. Employing various surveying techniques such as road cruising, field surveys, coverboards, and opportunistic captures we have successfully documented eight species of snakes, including: eastern king snakes (Lampropeltis getula), banded water snakes (Nerodia fasciata), yellow rat snakes (Elaphe obsoleta), southern ringneck snakes (Diadophis punctatus), eastern garter snakes (Thamnophis sirtalis), rough green tree snakes (Opheodrys aestivus) and black racers (Coluber constrictor).
When a snake is captured it is brought to the Georgia Sea Turtle Center (GSTC) where it is measured, weighed, and sexed. Each snake is also branded using a small portable cautery device. Branding is a permanent form of tagging that facilitates identification of the individual on subsequent encounters. Data collected will be used to monitor the status of snake populations as well as overall ecosystem health on Jekyll Island.
Venomous snakes are present on the island. To date, cottonmouths (Agkistrodon piscivorus) and eastern diamondback rattlesnakes (Crotalus adamanteus) have been confirmed. These snakes present an interesting management issue as venomous snakes in urbanizing areas can sometimes result in potential risks in human-dominated areas. Research on habitat use and movement patterns is vital to understanding the ecological needs of venomous snakes. Furthermore, it is necessary to assess management alternatives, such as relocation of individual snakes in order to reduce encounter risks of residents and visitors.
Thus, as of September 2011 we began implanting large eastern diamondback rattlesnakes with transmitters for use in a radio telemetry study. This study will serve as an elaboration of research being done on canebrake rattlesnakes at Palmetto Bluff, Beaufort County, SC by Dr. Kimberly Andrews and Joseph Colbert in conjunction with Palmetto Bluff Conservancy. Telemetry data will provide information on the home range sizes, site fidelity, and overwintering ecology of eastern diamondback rattlesnakes on Jekyll Island. Also, this approach is important for determining the effects of development on eastern diamondback rattlesnake populations because individuals might respond to development in ways that cannot be detected through a traditional mark-recapture, population-level study. For example, individuals could redistribute and adjust home range size, home range location, and habitat use to avoid disturbance associated with development. Such a response at the individual level might not immediately affect survival and thus not be detectable at the population level. Conversely, rattlesnake populations might not redistribute in response to development, in which case we expect increased human-wildlife interaction to reduce rattlesnake survival. Thus, we use radio telemetry data to examine home range and habitat parameters to detect individual responses to development. Further, on-going collection of radio telemetry data will allow us to develop known-fate survivorship models that can be used to predict population change in response to development activities. Additionally, visual encounter surveys in salt marshes and maritime forests are conducted to further assess status and detectability of eastern diamondback rattlesnakes on Jekyll Island while allowing for the collection of baseline data.
A study started by Dr. Andrews with canebrake rattlesnakes (Crotalus horridus) in South Carolina on relocation as a “last resort” management tool will be initiated on Jekyll Island. While most captures are managed through public awareness and the provision of tools needed to establish the appropriate comfort level to release individuals at their point of capture some locations are deemed inappropriate as they present direct risk to the animal due to the high potential for human interaction. However, before establishing relocation protocols, we must develop an understanding of whether relocated rattlesnakes can survive and establish in a new location as opposed to recurring at their original point of capture. Relocation results on rattlesnakes are inconsistent and need further articulation in order to develop recommendations for planners and managers. The development of these protocols could be disseminated and applied within the states of South Carolina and Georgia for both species of rattlesnakes. Further, these data facilitate the development of wildlife management protocols where alternatives must be employed.
Jekyll Island, as a State Park that also contains residential, recreational and commercial development, serves as an ideal location to investigate patterns of space use and survivorship in human-dominated landscapes. Since Jekyll Island is a State Park, management of native wildlife is a priority for biologists and managers on the island. Further, a Conservation Plan was finalized in summer 2011 that includes biological exploration as a priority for retaining native species that pose potential risk to inhabitants and visitors.