TY - JOUR
T1 - Demographic effects of road mortality in black ratsnakes (Elaphe obsoleta)
AU - Row, Jeffrey R.
AU - Blouin-Demers, Gabriel
AU - Weatherhead, Patrick J.
N1 - Funding Information:
We are grateful to the numerous field assistants that have helped us with fieldwork over the years. In particular, we are grateful to J. Svec for dutifully collecting road kill information in 1997. We thank J. Brennan, J. Tews, and L. Tischendorf for helpful discussions on population viability analyses, T. Robb for her help with coding in R, and the staff at the Queen’s University Biological Station for logistical support. We acknowledge Parks Canada (including support from J. Leggo and K. Prior), the Ontario Ministry of Natural Resources (including support from S. Thompson), the Natural Sciences and Engineering Research Council of Canada, the University of Illinois, and the University of Ottawa for funding our long-term studies on ratsnakes.
PY - 2007/6
Y1 - 2007/6
N2 - Roads negatively affect animal populations by presenting barriers to movement and gene flow and by causing mortality. We investigated the impact of a secondary road on a population of black ratsnakes (Elaphe obsoleta) in Ontario, Canada by radio-tracking 105 individuals over 8 years. The road was not a significant barrier to movement and none of the reproductive classes examined (male, non-reproductive female, reproductive female) avoided crossing the road. However, the road was a significant source of mortality. From a total of 115 road crossings by radio-implanted snakes, 3 individuals were killed by cars, resulting in a mortality rate of 0.026 deaths per crossing. We multiplied this mortality rate by the total number of expected road crossings by all individuals in the population in an active season (340) to estimate the number of road kills (9 individuals) each year. This estimate was higher than the actual number of road kills found, but half the number estimated from road kill models. Population viability analysis revealed that our estimate of road mortality was enough to increase the extinction probability for this population from 7.3% to 99% over 500 years. Road mortality of more than 3 adult females per year increased the extinction probability to >90%. Our results strengthen the view that road mortality can have a pronounced negative effect on populations of long-lived species.
AB - Roads negatively affect animal populations by presenting barriers to movement and gene flow and by causing mortality. We investigated the impact of a secondary road on a population of black ratsnakes (Elaphe obsoleta) in Ontario, Canada by radio-tracking 105 individuals over 8 years. The road was not a significant barrier to movement and none of the reproductive classes examined (male, non-reproductive female, reproductive female) avoided crossing the road. However, the road was a significant source of mortality. From a total of 115 road crossings by radio-implanted snakes, 3 individuals were killed by cars, resulting in a mortality rate of 0.026 deaths per crossing. We multiplied this mortality rate by the total number of expected road crossings by all individuals in the population in an active season (340) to estimate the number of road kills (9 individuals) each year. This estimate was higher than the actual number of road kills found, but half the number estimated from road kill models. Population viability analysis revealed that our estimate of road mortality was enough to increase the extinction probability for this population from 7.3% to 99% over 500 years. Road mortality of more than 3 adult females per year increased the extinction probability to >90%. Our results strengthen the view that road mortality can have a pronounced negative effect on populations of long-lived species.
KW - Ontario
KW - Population viability analysis
KW - Reptile
KW - Road avoidance
KW - Road mortality rate
UR - http://www.scopus.com/inward/record.url?scp=34047181526&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=34047181526&partnerID=8YFLogxK
U2 - 10.1016/j.biocon.2007.01.020
DO - 10.1016/j.biocon.2007.01.020
M3 - Article
AN - SCOPUS:34047181526
SN - 0006-3207
VL - 137
SP - 117
EP - 124
JO - Biological Conservation
JF - Biological Conservation
IS - 1
ER -