Effectiveness of light-reflecting devices: A systematic reanalysis of animal-vehicle collision data

Wildlife warning reflectors and white canvas reduce deer–vehicle collisions and risky road‐crossing behavior

“…These typically attempt to modify driver or animal behavior and include driver warning signs, reduced speed limits, deer whistles, mirrors, and reflectors. Yet studies of these methods have mostly shown limited to zero effectiveness (D'Angelo and van der Ree , Huijser et al , Brieger et al ).…”

“…Previous studies of the effectiveness of wildlife warning reflectors have produced results ranging from no effect to 97% reduction in carcass rates (Table ). This wide variation has led to a general conclusion that wildlife warning reflectors are not reliably effective (D'Angelo and van der Ree , Brieger et al ). We found that reflectors reduced deer–vehicle collisions by 33% compared with when reflectors were covered with nonreflective black canvas, which was a moderate reduction but considerably less than the 50–97% reported in some previous studies (Schafer and Penland , Pafko and Kovach , Grenier ).…”

“…Although many studies have found no effect of reflectors on collision rates, as measured via carcass counts (Woodard et al , Waring et al , Armstrong , Ford and Villa , Reeve and Anderson ), other studies have found that reflectors reduced collision rates by anywhere from 19–90% (Gladfelter , Schafer and Penland , Pafko and Kovach , Gulen et al ). A recent meta‐analysis of all light‐reflecting devices, including reflectors and mirrors, found no consistent effect of these devices on collision rates (Brieger et al ). Study designs have been highly variable among these studies.…”

“…Study designs have been highly variable among these studies. Many studies have relied upon before–after comparisons, which is problematic given that wildlife–vehicle collision rates can vary from year to year at a specific location because of annual fluctuations in deer activity (Brieger et al ). Other studies have used case‐control designs with questionable controls, such as substantially fewer carcasses at the control site relative to the treatment site before the reflectors were installed (Gladfelter ).…”

“…In another study, deer were found to react to reflectors initially but became increasingly habituated over a period of 17 days, suggesting no long‐term effect of the reflectors on deer behavior (Ujvári et al ). The lack of consistent deer behavioral responses to reflectors, coupled with inconclusive or weak evidence from carcass counts, has led some to conclude that reflectors are ineffective (D'Angelo and van der Ree , Brieger et al ).…”