Squirrels, cats top count to date: Student roadkill census heads into second year
From ANIMAL PEOPLE, October 1993:
DERRY, New Hampshire––Roadkill Monitoring
Project coordinator Brewster Bartlett, a.k.a. Dr. Splatt, has
announced that March 14 through May 15 will be the 1994
roadkill survey period for school groups.
Last year students at 31 schools participated, all of
them in New England. This year, Bartlett hopes to recruit
several hundred, from all parts of the U.S. and Canada.
“Each student is assigned a road that is frequently
traveled going to and from school,” Bartlett explains. “This
road is to be monitored at least twice a day for at least eight
out of the nine weeks.” Each Monday, student roadkill
counts from the preceding week will be tabulated and
relayed by computer modem to a Roadkill Bulletin Board
maintained by Simmons College, in Massachusetts.
“The purpose of the Roadkill Monitoring project is
twofold,” according to Bartlett. “We involve students and
teachers in scientific monitoring and telecommunications,
and we increase participant awareness of motor vehicle haz-
ards to wildlife.” The project incorporates lessons in natural
history, biology, driver education, English, math, and
computer studies. Teachers discovered last year that it
proved particularly effective in involving otherwise unmoti-
vated students.
Results used in prevention
When complete, the Roadkill Monitoring Project
data will be integrated with the data currently being gath-
ered by ANIMAL PEOPLE readers, in an effort to pro-
duce accurate estimates of the impact of roadkills on
wildlife populations and to identify means of reducing the
toll. Last year’s Roadkill Monitoring Project found that
many species, including squirrels, raccoons, rats, and
beavers, are killed in greatest numbers during relatively
brief peak periods of vulnerability, which may coincide
with feeding and migration patterns, and perhaps with
moon phases. If these peak periods prove predictable,
many roadkills might be prevented by simply adding animal
alerts to radio traffic reports.
Already Metro Traffic Report, of Los Angeles,
and Holland Van Dieren of the Ark Trust are collaborating
to develop animal alerts based on the Roadkill Monitoring
Project preliminary findings and the ANIMAL PEOPLE
guide to how various species behave around cars, published
last November.
Preliminary findings
Proportionally weighted to reflect the New
England urban/rural population balance, the 1993 Roadkill
Monitoring Project data suggests that there are an average of
.93 roadkills per mile per week, regardless of habitat.
Apparently the greater volume of traffic in urban areas com-
pensates for the smaller number of animals. The propor-
tionally weighted species count suggested that of the annual
toll, squirrels account for 22%; cats 14%; rats 12%; opos-
sums 10%; raccoons 8%; and dogs 2%. Raccoons may be
underreported because the recent spread of raccoon rabies
into New England has encouraged municipal authorities to
promptly remove raccoon carcasses. Overall, mammals
would make up 82%of counted roadkills; 15% would be
birds; and 3% would be reptiles and amphibians. Many
smaller amphibians may have escaped the notice of the
counters.
Because last year’s roadkill monitoring project
covered only New England, and only during two months of
the spring, the information is subject to considerable distor-
tion when used as a basis for estimating the number of road-
kills nationally. At the same time, it is nonetheless the
most thorough collection of roadkill data to date; previous
national estimates of the roadkill toll at “a million a day” are
largely based on a count taken in suburbs of Washington
D.C. by volunteers with the Humane Society of the U.S., on
a single day in 1957, and are therefore even more distorted.
If the New England data is confirmed by findings
from elsewhere around the country at other times of year,
roadkills claim 514,000 animal lives daily, or half the
HSUS projection, coming to 3.6 million animals per week
and 187 million per year. This would include annual tolls of
41 million squirrels, 26 million cats, 22 million rats, 19
million opossums, 15 million raccoons, and five million
dogs, as well as 350,000 deer and 130 human beings who
die in animal/car collisions.
Homeless cats
The projected number of cats killed by cars is
identical, by coincidence, to the number of homeless cats
estimated to live in the U.S. by Animal Cat Allies cofounder
Louise Holton. Holton derived her feral cat population esti-
mate by assuming the same ratio exists between owned and
homeless cats in the U.S. as in South Africa, where feral
cats have come under close study for longer. A N I M A L
PEOPLE puts the number of feral cats higher, at 35 mil-
lion, by projecting cats-per-square-mile data developed for
specific population densities during several cat rescue pro-
jects, which like the first year of the Roadkill Monitoring
Project were undertaken exclusively in New England. Both
methods of estimating have glaring flaws. The Roadkill
Monitoring Project may provide a third method of estimat-
ing the homeless cat population, perhaps no more accurate
by itself but useful in either confirming or refuting the oth-
ers.
Data gathered by ANIMAL PEOPLE during a
1992 national survey of cat rescuers found that roadkills
accounted for 10% of the mortality among homeless cats
whose cause of death was known to the rescuers, and 20%
of the mortality among homeless cats who were not eutha-
nized either by rescuers or animal control departments. The
number of homeless cats euthanized in shelters last year
came to approximately 3.5 million, according to the most
accurate available estimate (see story beginning on page
one). This would indicate that shelters handle from 10% to
14% of the homeless cat population.
If most of the cats killed by cars each year are
homeless, as a 1990 study done in Baltimore indicated, if
the 26 million figure is accurate, and if 26 million is only
20% of the mortality among the homeless cats who are not
euthanized, the total number of homeless cats could come
to 132 million––or more than two for every pet cat. But the
26 million figure may be too high by an astronomical mar-
gin; the Roadkill Monitoring Project counting period coin-
cides with what shelter personnel call “kitten season,” when
the most litters are born, and consequently, the most kittens
are exposed to traffic. If the Baltimore findings are project-
ed across the U.S., only 1.5 million cats per year are killed
by cars. Averaging the two estimates of feline roadkill mor-
tality would produce a more plausible projection of 13.75
million per year, from a homeless cat population of about
68 million––just slightly more than the estimated 61 million
cats who have homes.
Such issues can only be resolved by gathering
more data. Teachers who wish to have their classes join the
1994 Roadkill Monitoring Project may contact Bartlett at
Pinkerton Academy, 19 North Main Street, Derry, NH
03038; 603-432-2588; or by modem at BBartlett@vmsvax-
