Roadside carrion is a sure sign of spring, and when I saw a raccoon shuffling along the
shoulder of the interstate highway in full daylight today, I wondered about its prospects
for longevity. After a long winter, both hunger and the urge to mate compel raccoons to
travel, and of course the Interstate is very convenient. But what are the odds this animal
will see another spring?
Seeing an adult raccoon behaving oddly is, of course, also a potential sign of danger to
people. The masked one can suffer from a number of pathogens including rabies,
distemper, and infectious roundworms. The chances are good that the roadside raccoon
was simply on a quest for food and love, but with raccoons, you can never be sure.
Raccoons can meet their ultimate fate in many ways. Predators, including owls and
coyotes, take kits when they are out and about in summer. Vehicle collisions, hunting,
rabies, and distemper are the other chief causes of mortality. Life expectancy is only one
to three years, with only about half of all males surviving their first year.
Raccoons prefer to live along streams, where they canvass the streambanks for crayfish,
frogs, berries, nuts, and just about anything halfway edible. Their omnivory, along with
their opposable thumbs, binocular vision, and relentless curiosity is not unlike that of a
north woods primate. Their hankering for corn and chicken, along with dog food and
fragrant trash, frequently leads them into conflict with humans.
Raccoons are rightly known as a reservoir for the rabies virus, which humans can
contract through a bite with exposure to saliva or being exposed to brain and nerve tissue.
The current rabies epizootic began in the 1950s, when it was first reported in the
southeastern states. In the 1970s, rabid raccoons showed up in the mid-Atlantic states.
From there the virus spread up the Hudson River Valley and arrived in Vermont in 1992.
In New Hampshire, reports of rabies among raccoons are highest along the Seacoast and
are increasing every year. Nineteen incidents were reported in 2006 in New Hampshire.
Only in 2006 was the first rabid raccoon confirmed in the Province of Quebec. Wildlife
officials are working to slow the spread of rabies by distributing tasty baits, laced with an
oral rabies vaccine, along the international border.
Vermont reported 42 cases of rabies in 2006. The highest density of raccoons living in
the state was found in St. Albans, with 10 raccoons living in each square kilometer. Just
north of the current northern limit of the virus, populations reach 12 per square kilometer
in good habitat in Quebec. Once rabies arrives, the population will likely drop by half.
To put those numbers in perspective, in the Southern U.S., where the living is easy (for
raccoons), and the virus is not present, raccoon populations can reach as high as 69
animals per square kilometer. A Missouri marsh was found to host an astonishing 400
animals per square kilometer, or roughly two per acre.
Rabies among raccoons in the U.S. peaked around 1993. The total incidence has declined
since then, but the virus is still a considerable danger. To protect yourself, avoid animals
acting oddly: too friendly or too fierce, or up and about and in the open in the middle of
the day. Call a game warden if you see an animal that is clearly ill.
A less well known threat to humans from raccoons than the rabies epizootic is the
parasitic raccoon roundworm, Baylisascaris procyonis. This parasite completes a key part
of its reproductive life cycle in the raccoon’s intestine. The eggs are then dispersed with
the host’s scat. A single adult worm may produce 115,000 to 877,000 eggs per day, and a
heavily infected raccoon can shed as many as 45 million roundworm eggs daily.
Roundworm eggs can be accidentally ingested by birds and mammals, including humans,
with typically fatal results. Larvae migrate to the heart, eyes, and brains of these non-
target hosts, where they can cause a deadly form of meningoencephalitis. Human
toddlers, living hand to mouth and with a propensity to taste anything that they stumble
across, comprise most of the documented cases among humans. Between 40 and 60
percent of the raccoons in Vermont host these roundworms. Don’t handle scat with your
bare hands.
In captivity, with a decent health care plan, raccoons can live up to 20 years. But
emerging from a winter’s fitful sleep, a raccoon can find only too many easy ways to
encounter an early death. On a sunny morning by the interstate, a raccoon faces tough
odds indeed.