Chapter 1: A Literature Review of Wildlife-Vehicle Collisions

The overall focus of this report will be on the topic wildlife-vehicle collisions (WVCs). The first section will review the past observations made and studies conducted, while the second section will focus on answering the question “which factors have the strongest influence on WVCs in the Waterloo region?” The theory of why, how, when and where WVCs occur has been extensively studied in the past century with observations starting in the early 20th century. This report will present these findings in chronological order.

1920s

During the early 20th century, the automobile was invented, making WVCs a common occurrence in all industrialized nations. Joseph Grinnell, a wildlife biologist from California, was the earliest observer of the phenomenon of WVCs. Grinnel (1920) noted how "roadkill is a relatively new source of fatality; and if one were to estimate the entire mileage of such roads in the state California, the mortality must mount into the hundreds and perhaps thousands every 24 hours." The study of WVCs began because of this statement, with scientists now being able to connect the use of roads with the extinction of certain wildlife species.

Dill (1926) focused his observations on the decline of red-headed woodpecker (Melanerpes erythrocephalus) populations in Iowa. A main observation of Dill’s (1926) was how, based on the content of human food found in the birds stomachs, these woodpeckers seemed to be -in part-attracted to the road by the lunch waste of humans. Dill (1926) observed fewer dead woodpeckers on less heavily travelled roads. Baldwin (1926) contested the theories made by Dill (1926) about why these woodpeckers were found dead on the side of the road noting that he had no evidence that it was because of motorist...

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...944) observations made further supported the original theory made by Jones (1927) that the country roads (which had less traffic and a lower travelling speed) ultimately had lower amounts of roadkill. Haugen (1944) also notes how “the present federal law reducing speed limits to 35 miles an hour probably is causing some reduction in kill of game on highways.” Finally, Haugen (1944) mentions how the data produced from these wildlife road mortality studies may not always be completely accurate because predators may remove the wildlife killed from the side of the road. As previously reviewed, Robertson (1930) was the first to consider the importance of the surrounding habitat to the level of wildlife mortality observed and Haugen (1944) had a similar conclusion highlight how “seasonal changes in cover may in some places affect the rate of kill of animals on highways.”