A before-after-control-impact study of wildlife fencing along a highway in the Canadian Rocky Mountains

Wildlife exclusion fencing has become a standard component of highway mitigation systems designed to reduce collisions with large mammals. Past work on the effectiveness relied heavily control–impact (i.e., space-for-time substitutions) and before–after study designs. These designs limit inference may confound co-occurring process that also changes rate collisions. We used replicated ( n = 2 sites monitored for over 1000 km years combined) before-after-control-impact design assess along Trans-Canada Highway in Rocky Mountains Canada. found declined common ungulates species (elk, mule deer, white-tailed deer) by up 96% but not carnivores. The weak response carnivores is likely due combination fence intrusions low sample sizes. calculated realized applying same change collision rates observed at control (unfenced) as expected adjacent fenced sections. Compared apparent difference WVCs before after was installed), estimates 6% one site increased 10% another site. When factoring cost ungulate society, provided net economic gain within 1 year construction. Over 10-year period, would provide > $500,000 per reduced Our highlights benefits long-term monitoring road projects provides evidence reducing wildlife–vehicle involving