The Suitability Of Large Culverts As Crossing Structures For Deer

Scientific Disciplines
Biological Sciences - Terrestrial
Montana State University
Flathead Indian Reservation
Western Transportation Institute
Volume 17, No. 1-4

The suitability of large culverts as crossing structures 
For deer
Jeremiah Purdum, Western Transportation Institute, Montana State University, P.O. Box 17883 
Missoula, Montana 59808,
Marcel P. Huijser, Western Transportation Institute, Montana State University, P.O. Box 174250 
Bozeman, Montana 59717-4250,
Whisper Camel, Confederated Salish and Kootenai Tribes, P.O. Box 278, Pablo, Montana 59855,
Len Broberg, Environmental Studies Program, University of Montana, Jeanette Rankin Hall 106A, 
Missoula, Montana 59812-4320,
Pat Basting, Montana Department of Transportation, P.O. Box 7039
Missoula, MT 59807-7039,
Most researchers that have investigated the use of wildlife crossing structures have 
done so through counting the number of animals present in the structures or the number of 
animals that crossed the road using the structures. However, we argue that crossing structure 
acceptance, as a percentage of all approaches, is a better measure of suitability. Once the 
acceptance of certain types and dimensions of crossing structures is known for different 
wildlife species, agencies can select crossing structures that meet certain goals. We used 
this method for one particular type of crossing structure; large diameter culverts. We placed 
wildlife cameras (Reconyxâ„¢) at the entrance of nine corrugated metal arched culverts located 
along US Highway 93 on the Flathead Indian Reservation, Montana; to capture approach 
behavior. We specifically examined the number of successful and aborted crossing attempts. 
White-tailed and mule deer were the most frequently observed species and had an acceptance 
rate of 84 percent (n = 455) and 66 percent (n = 56) respectively. Only 49 percent (n = 426) of 
the groups that passed the structures successfully showed an alert posture versus 93 percent (n 
= 98) for the groups that aborted the attempts. The two deer species showed slightly different 
levels of alertness with an alert posture for 55 percent of white-tailed deer (Odocoileus 
virginianus) events and 68 percent for mule deer (O. hemionus)events for all crossing 
attempts combined. The data show that wildlife acceptance rates and behavior at structures 
can vary between species and data on varying structure type and dimensions will add to our 
understanding of structure acceptability for various target species.