Deer-Vehicle
Collissions
December
2007
Kip Adams, QDMA Director
of Education and Outreach, Northern Region
Overabundant herds cause
hundreds of millions in damage each year to the forestry
and agricultural industries and they
damage homeowners’ shrubs, flowers, ornamentals and
vegetable gardens. While these damages are costly, they
don’t compare
to the expense caused by deer-vehicle collisions (DVCs).
According to Dr. Michael Conover, Director of the Berryman
Institute at Utah State University, DVCs are responsible
for an estimated 200 human fatalities, 29,000 injuries and
over $1.1
billion in property damage each year.
The Insurance Institute for Highway Safety estimates there
are 1.5 million DVCs each year in the U.S. Given there are
about
32 million whitetails in the U.S., this suggests one of
every 21 deer will be involved in a DVC. These DVCs are a
public
safety concern and a waste of a natural resource, in
addition to being a personal expense for motorists. DVCs
occur most
often at dawn and dusk and during spring (fawning) and
autumn (breeding). Since the peak of the rut has just
passed for
many whitetail herds, this is a timely topic for hunters,
managers and other whitetail enthusiasts.
Actual DVC data is difficult and time consuming to collect.
Obtaining comparable data among states is even more
difficult
as some do not record this information while others rely on
various state agencies or private contractors for their
figures.
Fortunately, State Farm Insurance Company compiles a
state-by-state list of projected DVCs based on their
insurance claim
reports. This data may or may not be completely accurate
for a given state, but it is the best data available to
track annual
DVCs within a state and compare DVCs among states. The
following statistics are from State Farm.
My home state of Pennsylvania has led the nation four of
the past five years in DVCs by averaging about 99,000 per
year.
Michigan led the nation once and has been second four of
the past five years by averaging about 93,000 DVCs.
Pennsylvania
and Michigan more than double the average of the next top
five states. At the other end of the spectrum, Hawaii
averages less than 50 DVCs per year. In the continental
U.S., the District of Columbia and Nevada average about 300
and
900 per year, respectively. The top 10 states for DVCs over
the past five years are Pennsylvania, Michigan, New York,
Ohio,
Illinois, Virginia, Wisconsin, North Carolina, Georgia and
Texas.
Many factors impact the number of DVCs. Growing human and
deer densities, urbanization, development, proximity of
forested areas to roadways, and number of vehicles, road
miles, and miles traveled are a few. Texas and California
lead the
nation in public road miles and vehicle miles traveled but
rank 10 and 19 in DVCs. While Pennsylvania and Michigan
lead
the nation in DVCs, they are ranked 8 and 9 in the number
of road miles and miles traveled. Pennsylvania also leads
the
nation in the average number of DVCs per mile of road.
Pennsylvania motorists hit one deer for every 1.22 miles of
public
road. Similarly, Maryland drivers hit one deer for every
1.23 miles of public road. Conversely, Hawaii motorists hit
a deer
for every 100 road miles, and Nevada motorists hit one for
every 33 miles.
You can also analyze DVCs by the number of vehicles in a
state. West Virginia leads this list with a DVC for every
57 vehicle
registrations. West Virginia drivers are 5,000 times more
likely to hit a deer than get struck by lightning during
the next 12
months. Michigan (1 in 86), Wisconsin (1 in 99),
Pennsylvania (1 in 100) and Iowa (1 in 109) round out the
top five, and
the national likelihood of hitting a deer is 1 in 216. My
chances of hitting a deer were much lower at my former
residences
in Florida (1 in 1,273) and New Hampshire (1 in 390),
although the odds of hitting an alligator or moose were
much
higher.
An additional way to analyze this data is
to compare the number of DVCs to the legal harvest by
hunters. Ideally, DVCs
would be equivalent to a small percentage of the legal
harvest. Looking at the top 10 DVC states in 2006-07
reveals that
DVCs averaged 20% of the 2006 legal harvest in those
states, meaning that motorists hit a deer for every five
taken by hunters.
Texas and Wisconsin lead the list with DVCs equivalent to
only 9% of their legal harvests. New York is at the bottom
of the top 10 with DVCs equivalent to 34% of its 2006 legal
harvest. Ohio and Pennsylvania are close behind with DVCs
equivalent to 27% of their 2006 harvests.
How can you reduce DVCs? Various techniques from
“deer whistles” to wildlife warning reflectors
to signs and fences
have been tried. Deer whistles emit high frequency sounds
that supposedly scare deer from roadways. Research on the
hearing ability of deer reveals they don’t hear well
in the high frequency range, and there is no data to
support that deer
whistles deter deer from entering roadways or reduce DVCs.
Wildlife warning reflectors supposedly deter deer from
entering
roadways by using light from oncoming vehicles to provide
an “optical warning fence” to deer. Dr. Gino
D’Angelo and
his colleagues at the University of Georgia found the
reflectors were ineffective in preventing DVCs. They also
noted that
reflectors using red and blue lenses actually increased the
likelihood of a DVC. Road signs are used by many states to
alert
drivers to the possibility of deer entering the roadway.
Signs in new locations may work temporarily, but drivers
quickly acclimate
to them and their effectiveness declines. Fences can
successfully keep deer and other wildlife off roadways but
they
can also block travel corridors and alter movement
patterns. Fences are also expensive to erect and recent
research by the
U.S.D.A. Animal and Plant Health Inspection Service showed
a minimum of 7- to 8-foot fences are necessary to keep the
majority of deer from jumping over them. In their trials,
91% of deer jumped a 6-foot fence while only one deer
jumped a
7-foot and no deer jumped an 8-foot fence.
In closing, let’s look at one final piece of DVC
data. Of the top 10 DVC states, the average number of DVCs
has increased
over 9% from 2002-03 to 2006-07. North Carolina leads this
list with a 31% increase. Only two of the top 10 states
have
fewer DVCs today than in 2002-03. New York has nearly 3%
fewer, and Pennsylvania reduced the number of DVCs by
nearly 12% from over 111,000 to just over 98,000. This
reduction is over 20 percentage points above the average
– kudos
to the Keystone state! While this may still be a lot of
DVCs, Pennsylvania implemented a progressive deer
management
program in 2002 and a large reduction in DVCs is just one
of its many benefits. So, what’s the best technique
for reducing
DVCs? Balancing the deer herd with the available habitat.
For more information on DVCs and devices designed to
minimize them visit
www.forestry.uga.edu/h/research/wildlife/
wildlife/devices. This University of Georgia website
includes a comprehensive annotated bibliography on the
Evaluation of
Strategies Designed to Reduce Deer-Vehicle
Collisions.
Kip’s Korner is written
by Kip Adams, a Certified Wildlife Biologist and Northern
Director of Education and Outreach for the Quality Deer
Management Association (QDMA). The QDMA is an
international nonprofit wildlife conservation organization
dedicated to ethical hunting, sound deer management and
preservation of the deer-hunting heritage. The QDMA
can be reached at 1-800-209-DEER or www.QDMA.com.