To the Carcass in the Road, I’m Sorry

As someone who drives 23 miles each direction on my way to and from work, I cover a lot of pavement. I have a beautiful drive on a state route that follows along a major river, passing through forested and agricultural lands. During the warmer months, I often have the pleasure of seeing a bald eagle soaring over the river, or turkeys and deer grazing what’s left of the corn fields. Unfortunately, along my 23 mile drive, I often see many dead animals as well, particularly at this time of year and again in the fall.

*Side story: While in the process of writing this article, I was up in northern New Hampshire delineating wetlands for work, and a moose ran out in front of the car I was in (I was carpooling with a co-worker). Luckily, he stopped in time as we were on the lookout knowing the habitat. However, it was definitely scary as moose hits often end in serious injury or fatality.* (the moose is pictured in the feature image and was not injured).

It can be difficult to estimate wildlife mortality due to vehicular collisions, in part because of the lack of standardized surveying methods. One study that evaluated several existing methods and created a protocol for surveying roadkill. Using their protocol, they identified 413 individuals from 106 species along a 100km transect of road in a 40-day period¹ (holy numbers!) It is generally believed that most roadkill surveys underestimate wildlife mortality due to vehicular collisions, in part because not all animals die on impact but manage to run off the road before dying.

In New England and other regions with similar seasonal variation, animal activity changes with the seasons². Spring and fall are typically when animals are most active, preparing for winter in the fall and emerging in the spring to take advantage of the bountiful resources. Fall and spring also coincide with breeding seasons, resulting in increased activity as animals roam their territory looking for mates. Lastly, most animals give birth to their young in the spring, with the parents having to gather extra food to feed them. All of these factors influence the movement of animals and therefore can result in variation of wildlife collision frequency.

If you see an animal you think may be alive but injured, you should immediately contact a local wildlife rehabilitator. Wildlife rehabbers must be licensed by their state and can also obtain a federal license to handle protected species. You can typically find a list of licensed rehabbers on your state’s fish and game/wildlife department website. When you contact your local rehabber, they will likely send a volunteer to come pick up the animal and transport them to the rehab facility. Another option is to keep a wildlife rescue kit in your car, typically consisting of an animal carrier, gloves, sheets, etc. However, you should still call a local rehabber so they can direct you in the safest way possible to handle and transport the animal. The Center for Wildlife, a rehab center I volunteered with in college, has a great website with plenty of resources: https://www.thecenterforwildlife.org/rescue.

There has been an increasing awareness of the impact roadways have on wildlife populations. With that, there has also been a rise in the study and implementation of wildlife crossing structures and mitigation strategies to help reduce collisions and roadkill. These strategies range from signage in areas of high animal activity like turtle, moose, and deer crossings, to wildlife overpasses like those in Montana. My college had an underpass walkway to allow students to cross under a major road, that also had documented use by wildlife from skunks and raccoons to deer and fox.

Wildlife mitigation strategies depend on the frequency of wildlife-vehicle incidents and severity or cost per incident. More extensive mitigation strategies such as fencing, overpasses, and underpasses are most cost effective for areas that have higher and more severe rates of wildlife-vehicle collisions per year, while lower cost strategies like signage are more feasible for lower frequency and severity collision areas³. Time of year, surrounding habitat, and species all influence likelihood and severity of wildlife-collision rates.

What are the take aways:

• There’s no standardized method for estimating wildlife mortality rates due to vehicular collisions, therefore it’s hard to fully understand the impact cars and roadways have on wildlife populations.
• If you find an animal in the road you think may still be alive, immediately contact a local wildlife rehabber. If you’re prepared with a wildlife rescue kit in your car, they may instruct you on how to properly secure the animal or send a registered volunteer transporter to meet you.
• There are many wildlife collision mitigation strategies, and the best fitting approach depends on species, surrounding habitat, and time of year. If you’re noticing high roadkill rates in a particular spot that has no existing mitigation, notify your municipal public works, state biologists, and applicable non-profit organizations.

Citations

1. Collinson, W. J., Parker, D. M., Bernard, R. T., Reilly, B. K., & Davies-Mostert, H. T. (2014). Wildlife road traffic accidents: A standardized protocol for counting flattened fauna. Ecology and Evolution,4(15), 3060-3071. doi:10.1002/ece3.1097
2. Smith-Patten, B. D., & Patten, M. A. (2008). Diversity, Seasonality, and Context of Mammalian Roadkills in the Southern Great Plains. Environmental Management,41(6), 844-852. doi:10.1007/s00267-008-9089-3
3. Huijser, M. P., Duffield, J. W., Clevenger, A. P., Ament, R. J., & Mcgowen, P. T. (2009). Cost-Benefit Analyses of Mitigation Measures Aimed at Reducing Collisions with Large Ungulates in the United States and Canada: A Decision Support Tool. Ecology and Society,14(2). doi:10.5751/es-03000-140215