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Current Herpetological Research Projects

• Western Diamondback Rattlesnake Abundance and Distribution

Western Diamondback Rattlesnake Abundance and Distribution

Summary

A new project is underway at The University of Arkansas at Monticello, that will help us better understand western diamondback abundance and distribution in Arkansas. A better understanding of abundance and distribution can lead to better management recommendations for this species. The lead PI on this project is Dr. Todd Fearer (http://www.afrc.uamont.edu/fearert/).

This project is being supported by a State Wildlife Grant from the Arkansas Game and Fish Commission (http://www.wildlifearkansas.com/Proposals2009.html) and by the Arkansas Forest Resources Center (http://www.afrc.uamont.edu/)

Project Title: Adapting a habitat model for timber rattlesnakes to assess the potential distribution of western diamondback rattlesnakes in Arkansas.

Project Summary: We will use habitat measurements with statistical modeling and aerial photography in geographic information systems (GIS) to measure and map areas of west-central Arkansas potentially containing western diamondback rattlesnake den site habitat. Our approach will attempt to adapt a method that successfully predicted timber rattlesnake basking habitat in Virginia. If successful, such a method will improve our knowledge of western diamondback rattlesnake abundance and distribution in Arkansas.

This project hopes to improve distribution and abundance data for western diamondback rattlesnakes in Arkansas. This project may also benefit conservation of the eastern collared lizard. This lizard shares some habitat preferences with western diamondback rattlesnake den site habitat (rocky outcroppings within forest stands, bare rocks and talus slopes) and their projected ranges overlap in portions of the Ouachita and Ozark Mountains. We will document any sightings of eastern collared lizards while conducting this project to improve distributional records through this portion of their range.

Objectives: The goal of this project is to develop a technique for predicting western diamondback rattlesnake den site habitat in Arkansas by adapting a technique used to measure timber rattlesnake habitat in Virginia. We will use aerial photos to produce a map predicting locations of den habitat in Arkansas and help plan site surveys for improving data on western diamondback rattlesnake distribution and abundance. The final completion date for all portions of this project is April 2011.

Study Location: The distribution of western diamondback rattlesnakes in Arkansas is likely limited to the Ouachita and Ozark Mountains in the west-central and northwest portion of the state. We will concentrate most of our efforts on the Ouachita and Ozark National Forests.

Methods: The presence of suitable habitat is one of the most basic requirements for a species’ existence in an area. Because little is known about the distribution of western diamondback rattlesnakes in Arkansas, their habitat preferences are poorly understood. However, a habitat that is likely crucial to western diamondbacks in Arkansas is exposed rocky areas used for den sites. After modifying a technique used in Virginia to successfully locate similar habitat for timber rattlesnakes, we feel that it can be used to identify potential western diamondback habitat because the land form, forest types, and management practices of the Ouachita and Ozark Mountains in Arkansas are similar to those of the Appalachian region of Virginia. Also, many of the characteristics of the habitat in this part of the western diamondback’s range can be distinguished using aerial photography.

We will visit known den sites during the late summer and fall of 2009 and collect habitat data to identify habitat characteristics distinctive to these areas. This will help us develop baseline information regarding den site characteristics and help identify critical habitat components that are easily distinguished using aerial photography.

During the fall of 2009 and winter of 2010, we will use the information collected at the locations of known den sites and a number of random sites to identify sites with similar habitat characteristics based on aerial photos and similar types of imagery and create a map of our study region identifying potential western diamondback rattlesnake denning habitat. After emerging from hibernation, western diamondbacks remain near the den for a few days before dispersing to summer ranges. After dispersing, individuals become very difficult to locate. Because snakes emerge from hibernation during March and early April in this part of their range, we will visit a subset of sites identified by our habitat map that are located on National Forest land during this time period. We will classify sites with snakes present as occupied. If a site contains suitable habitat but no rattlesnakes are observed, it will be classified as suitable and visited at later dates when snakes are most likely to be present and observed (fall 2010 and/or March-April 2011).