Roadkill is an animal or animals that have been struck and killed by motor vehicles. In the United States of America, removal and disposal of animals struck by motor vehicles is usually the responsibility of the state's state trooper association or department of transportation.
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During the early 20th century, roadkill or "flat meats" became a common sight in all industrialized First World nations, as they adopted the internal combustion engine and the automobile. Roadkill can be eaten, and there are several recipe books dedicated to roadkill. (See Roadkill cuisine) One of the earliest observers of roadkill was the naturalist Joseph Grinnell, who noted in 1920: "This [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."
In Australia, specific actions taken to protect against the variety of animals that can damage vehicles – such as bullbars (usually known in Australia as 'roo bars', in reference to kangaroos) – indicate the Australian experience has some unique features with road kill.[1] In North America, deer are the animal most likely to cause vehicle damage.
The Simmons Society was founded by Professor Roger M. Knutson of Luther College in Decorah, Iowa, US to further studies of road fauna. Professor Knutson also published a book called "Common Animals of Roads, Street, and Highway: A Field Guide To Flattened Fauna".[2]
A recent study showed that insects, too, are prone to a very high risk of roadkill incidence.[3] Research showed interesting patterns in insect/butterfly road kills in relation to the vehicle density. Although the insect community is equally at risk, much of the attention goes to bigger, more charismatic animals.
About 350,000 to 27 million birds are estimated to be killed on European roads each year.[4]
In 1993, 25 schools throughout New England participated in a roadkill study involving 1,923 animal deaths. By category, the fatalities were:[5]
Extrapolating these data nationwide, Merritt Clifton, editor of Animal People Newspaper estimated that the following animals are being killed by motor vehicles in the United States annually:[6]
This study may not have considered differences in observability among taxa (i.e. dead raccoons are easier to see than dead frogs), and has not been published in peer-reviewed scientific literature.
Recently (since 2009), statewide roadkill observation systems have sprung up, enrolling hundreds of observers in reporting roadkill on a website. The observers, who are usually naturalists or professional scientists, provide identification, location, and other information about the observations. The data are then displayed on a website for easy visualization and made available for studies of proximate causes of roadkill, actual wildlife distributions, wildlife movement, and other studies. Roadkill observation system websites are available for the US states of California [7] and Maine. [8] In both cases, index roads are used to help quantify total impact of vehicle collisions on specific vertebrate taxa.
The first wildlife roadkill identification guide produced by a state agency in North America was published by the British Columbia Ministry of Transportation (BCMoT) in Canada in 2008.[9] BCMoT’s “Wildlife Roadkill Identification Guide” focused on the most common large carnivores and ungulates found in British Columbia. The guide was developed to assist BCMoT's maintenance contractors in identifying wildlife carcasses found on provincial highways as part of their responsibilities for BCMoT’s Wildlife Accident Reporting System (WARS).[10]
In 1994, Michigan reported 56,666 deer collisions, of which five resulted in human fatalities, according to Mark Matthew Braunstein of the Santa Cruz Hub. The problem is so pervasive that, according to an article by Hank Pellissier of the San Francisco Chronicle, Michigan uses roadkill statistics to estimate its deer population.[11]
Collisions with animals can have many negative consequences:
Collisions with animals with antlers (e.g., deer) are particularly dangerous, as the head has a tendency to separate and come through the windshield, but any large, long-legged animal (e.g. horses, larger cattle, camels) can pose a similar cabin incursion hazard. Injury to humans due to driver failure to maintain control of a vehicle either while avoiding, or during and immediately after an animal impact, is also not infrequent.
Deer horns can be mounted on vehicles to warn deer of approaching automobiles, though their effectiveness is disputed.
The Jackson Hole Wildlife Foundation is an example of an organization advocating roadkill prevention.
Although strikes can happen at any time of day, deer tend to move at dawn and dusk, and are particularly active during the October–December mating season. Driving at night presents its own challenges: nocturnal species are on the move, and visibility, particularly side visibility, is reduced. When headlights approach a nocturnal animal, this makes it hard for the creature to see the approaching car (nocturnal animals see better in low than in bright light). Furthermore, the glare of vehicle headlights can dazzle some species, such as rabbits; they will freeze in the road rather than flee. The simple tactics of reducing speed and scanning both sides of the road for foraging deer can improve driver safety at night. Drivers may see the glow of a deer's eyes before seeing the animal itself.
Wildlife crossings allow animals to travel over or underneath roads. They are most widely used in Europe, but have also been installed in a few U.S. locations and in parts of Western Canada. As new highways cause habitats to become increasingly fragmented, these crossings could play a crucial role in protecting endangered species.
In the United States, sections of road known to have heavy deer cross-traffic will usually have a warning sign depicting a bounding deer. Similar signs exist for moose, elk and other species.
In the American West, roads may pass through large areas designated as "open range", meaning no fences separate drivers from large animals such as cattle or bison. A driver may round a bend to find a small herd standing in the road. Open range areas are generally marked with signage and protected by a cattle guard.
A few states now have sophisticated systems to protect motorists from large animals. One of these systems is called the roadway animal detection system. A solar powered sensor detects animals near the roadway and flashes a light to alert oncoming drivers.
In the New Forest, in southern England, there is a proposal to fence roads to protect the New Forest pony. However, this proposal is controversial.[12]
There has been at least one case in the United States where a jail inmate was allegedly forced to eat roadkill.