Clarkson ID

Dr. Tom A. Langen

Impact of Road Mortality on Turtles and other Herpetofauna


I am involved in three interrelated projects related to understanding and reducing road impacts on herpetofauna. Support for this research has come from the US Fish & Wildlife Service State Wildlife Grants Program (administered through the New York State Department of Environmental Conservation), the New York State Department of Transportation, the New York State Biodiversity Institute, and the Clarkson Center for the Environment.


Female common snapping turtle nesting along a highway.
Marilyn Gonzalez places a radiotransmitter on a painted turtle.

The first road research crew, in 2001.



Demographic Consequences of Road Mortality on Turtles.

The goal of this project is to measure the impact of road mortality and other road effects on survival and reproduction of three turtle species (snapping, painted and Blandingís turtles). Presently I am comparing the nesting success of turtles that nest on the verges of roads (a site favored by turtles) versus more natural areas.  I am also measuring the risk to adult turtles of death by collision with motor vehicles, by marking turtles that inhabit the vicinity of roads (using passive integrated transponders), and monitoring roads for turtle mortality. Finally I am are radio-tracking individual turtles to understand how their movements place them at risk.


Predicting Hotspots of Herpetofauna Road Mortality.


This project's goal is to develop an accurate, practical method of predicting hotspots of amphibian and reptile road mortality, so that hotspots can be located for mitigation. To accomplish this, I have been  validating methodologies for road mortality surveys. I use GIS to compare the results of road surveys (hotspots and coldspots of road mortality) with publicly-available data on land use, road features, and wetland features. At present, I am using the configuration of wetlands along roads to predict hotspots of road mortality along northern New York highways. I have found that it is possible to accurately predict hotspots of herpetofauna highway mortality in northern New York using GIS, which should be a great aid to road managers and others concerned with the effects of roads on reptiles and amphibians.


Preventing Herpetofauna Road Mortality Using Barriers & Culverts.

Barriers and passageways are technologies that are increasingly being mandated to prevent wildlife road mortality while preserving connectivity across both sides of a highway. I collaborate with civil engineers and Dept. of Transportation and Dept. of Environmental Conservation personnel on designing and field testing barrier designs for reptiles and amphibians. We are evaluating these barriers for effectiveness at preventing road crossing, unintended risks (increased predation, altered nesting behavior), durability, and cost. I am also examining whether water equalization culverts, which often occur near hotspots or road crossing, can serve as effective passageways for herpetofauna.


Selected Publications

Langen, T.A.. 2009. Predictive models of herpetofauna road mortality hotspots in extensive road networks: three approaches and a general procedure for creating hotspot models that are useful for environmental managers. Proceedings of the 2009 International Conference on Ecology and Transportation. reprint

Langen, T.A., K. Ogden, and L. Schwarting. 2009. Predicting hotspots of herpetofauna road mortality along highway networks. Journal of Wildlife Management 73: 104-114. reprint

Langen T.A., A. Machniak, E. Crowe, C. Mangan, D. Marker, N. Liddle, and B. Roden. 2007. Methodologies for surveying patterns of herpetofauna road mortality along a highway network. Journal of Wildlife Management 71:1361-1368. reprint


Steen, D.A., M.J. Aresco, S.G. Beilke, B.W. Compton, C.K. Dodd Jr., H. Forrester, J.W. Gibbons, J. Greene-McLeod, G. Johnson, T.A. Langen, M.J. Oldham, D.N. Oxier, R.A. Saumure, F.W. Schueler, J. Sleeman, L.L. Smith, J.K. Tucker,  J.P. Gibbs. Relative vulnerability of turtles to road mortality. 2006. Animal Conservation 9:269-273. reprint


Press Releases & Clippings (linked)


last updated 17 Aug 2010


free hit counters
free hit counters