SREL Reprint #3092

Roads as Catalysts of Urbanization: Snakes on Roads Face Differential Impacts Due to Inter- and Intraspecific Ecological Attributes

Kimberly M. Andrews and J. Whitfield Gibbons

Savannah River Ecology Laboratory, University of Georgia, Aiken, South Carolina 29802, USA

Abstract: Roads enable human access to previously undeveloped land and thereby are catalysts for urbanization. Assessments of the differential impacts of roads among and within wildlife species in pre-urbanized areas can offer insights into how species will be affected by roads in urban and suburban areas. We used a long-term (1951-2005) snake database from the Savannah River Site in South Carolina, USA to evaluate inter- and intraspecific differences among snakes captured on roads vs. off-road habitats. Data were collected on 15,697 snakes (35 species) of which 2,577 (29 species) were road captures. In evaluating differences in road-use between sexes of 15 species (n=1,574), we found that significantly more were males. In the analyses of individual species, 7 of the 15 were significantly male-biased and none were female-biased. Significantly more males than females were also collected in off-road habitats. However, the proportion of males (64%) observed in on-road specimens was significantly greater than that observed in off-road captures (54%). Of 2,233 captures of 17 snake species for which condition on road was known, significantly more were dead-on-road (DOR; 61%) relative to the number of alive-on-road (AOR). Eight species had significantly higher DOR frequencies compared to one with a significantly higher AOR frequency. For seven species, longer and heavier individuals were more likely to be DOR. Snakes captured on the road were significantly longer and heavier than those observed in off-road captures. On-road captures within species were significantly larger than off-road captures in five species and significantly smaller in one. Our findings indicate that when assessing the impact of roads and subsequent urbanization on snakes, attention must be given to the differential impacts roads have among species and in relation to individual sex and body size within species.

Keywords: Alive on Road, Body Size, Dead on Road, Ecology, Highway, Mortality, Sex Ratio, Snakes, Suburban, Urban

SREL Reprint #3092

Andrews, K. M. and J. W. Gibbons. 2008. Roads as Catalysts of Urbanization: Snakes on Roads Face Differential Impacts Due to Inter- and Intraspecific Ecological Attributes. In: J. C. Mitchell, R. E. Jung Brown, and B. Bartholomew (Eds.). Urban Herpetology. Society for the Study of Amphibians and Reptiles. Herpetological Conservation Number 3: 145-153.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).