By Mark P. Nelder, Public Health Ontario
William R Maples’ Dead Men Do Tell Tales: The Strange and Fascinating Cases of a Forensic Anthropologist, created a lasting memory for me. Aside from the fascinating science, Dead Men Do Tell Tales underscored that passion and resourcefulness is the key to learning.
With an interest in blowfly ecology and ectoparasites, I set out to study these two fields as side projects during my graduate research at University of South Alabama (MSc) and Clemson University (PhD). Yes, “side projects” is a phrase that can send any supervisor running in fear, but I was lucky.
During my research on black fly larvae and their gut fungi in Alabama, I initially thought that the undersides of bridges (easiest place to look for streams and black flies; #overlyhonestmethods) are where headless white-tailed deer went to die. These morbid scenes of poaching were both a source of amazement and one of convenience – easily accessed streams with black fly larvae accompanied by robust populations of blowflies and louse flies (my first sight of the very cool Lipoptena mazamae). These deer were just a gateway carcass, leading to a downward spiral of seeking out additional species of dead wildlife and their ectoparasites. I was now a roadkill prospector.
Realizing that I needed experience with ectoparasites, prior to starting research on biting flies and ectoparasites of South Carolina zoos, I turned to the sometimes flattened, bloated, and unrecognizable critters I saw on my daily drive to campus. Equipped with latest intelligence on a fresh carcass, all I needed was a garbage bag, latex gloves, and a vehicle.
Roads pose a real threat to animal populations. The numbers are staggering, as reported by @TetZoo or Darren Naish in Dead Animals at the Roadside. In Belgium, an estimated 230,000 and 350,000 hedgehogs fall victim to vehicles per year. Not exploring this biodiversity source would constitute a wasted opportunity.
Insects and roads do not mix either. In Japan, a study of two routes resulted in 5000 dead insects per kilometer, collections dominated by Coleoptera, Lepidoptera, and Diptera (Yamada et al. 2010).
Roadkill are ideal subjects for biodiversity studies (the vertebrate hosts, along with their ectoparasites and internal parasites). As One Health opens the doors to collaboration between the fields of human medicine, veterinary medicine, and the environment, scientists often remain confined in their respective silos. Roadkill offers a potentially important source of data on zoonoses and generate collaboration between veterinarians, entomologists, microbiologists, ecologists, and others.
Interest in roadkill science is about as old as the automobile, albeit slower wildlife succumbed to horse drawn carriages of the 1800s. AW Schorger had more than a passing interest in roadkill, identifying 64 species of birds from 1932 to 1950, on the same roads between Madison, Wisconsin and Freeport, Illinois. Avian roadkill was dominated by English (House) Sparrows (N = 2784), Red-headed Woodpeckers (389), American Robins (310), Ring-necked Pheasants (271), Screech Owls (235), and Northern Flickers (230). Imagine the possible research if Schorger had a curious entomologist to tag along on these trips and to inspect each bird.
Transportation ecology is a relatively new field that looks to study how wildlife interacts with our roads and how road design can minimize wildlife impact. The University of California Davis and partners have established a citizen-science project that allows the public to report roadkill on California highways, California Roadkill Observation System (see Maine and Idaho). Championed by the Toronto Zoo, the Ontario Road Ecology Group looks to combat the impact of roads on biodiversity in southern Ontario. Yet another is the South African initiative Wildlife Road Traffic Accidents – A Biodiversity Research Project. These programs offer an existing infrastructure that provides the basis for longitudinal studies of ectoparasites and their hosts.
Aside from the basic understanding of host-ectoparasite relationships, roadkill are increasingly becoming a tool for hypothesis testing. A few examples are worth mentioning here. The Cardiff University Otter Project provided road-killed otters to test hypotheses surrounding otters, ticks, and climate. The prevalence, but not intensity, of the tick Ixodes hexagonus infestation on otters was associated with higher Central England temperatures, while both prevalence and intensity were associated with positive phases of the North Atlantic Oscillation.
Without roadkill, we would not know that as lice burden increases in barn owls, the number of pectinate claw teeth decreases and bill hook length increases (Bush et al. 2012). Bush and colleagues also noted rodent ectoparasites on barn owls; e.g., the louse Hoplopleura acanthopus (normally found on rats) and the flea Malaraeus telchinus (from mice and voles). Is this a potential example of incipient evolution through host switching?
Roadkill prospecting excited me (and still does)….not unlike an unexplored stream has excited many a black fly expert, as an illuminated cloth at night for the moth lover, and as CDC light trap the mosquito ecologist. As Dr. Diane Kelly said in her excellent Story Collider tale Confronting Death on the Road
When you open up an animal, there is all kinds of awesome in there.