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Scientific
Classification of Wolves
Gray Wolves
Red Wolves
Ethiopian
Wolves
Wolf Prey and
Predation
 Yellowstone After Wolves
Depredation
(9 items)
Are
Wolves Endangered
IUCN
Manifesto on Wolf Conservation
Federal
Process of Reclassification and the Endangered Species Act
(4 items)
Frequently
Asked Questions About Wolf Management
Methods
Used for Estimating Wolf Abundance
Human Perspectives
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Updated October 2005
With the advent of radio-telemetry, and because wolves are territorial
pack animals, estimating their abundance is relatively straight-forward
compared to most other species of free-ranging wildlife.
When it is necessary to accurately estimate the number of wolves
in a particular area, wildlife biologists will radio-collar at least
one individual in each pack. This is accomplished by either live-trapping
wolves or darting or netting them from a helicopter. Though the
initial step of capturing and collaring wolves is time consuming,
estimating abundance afterward is comparatively easy.
A biologist will locate the radio-collared individual from an
airplane and count the number of other wolves traveling with it.
This is usually done during winter when snow provides excellent
background and tracking conditions for observing wolves. Because
the pack often splits as they hunt, multiple observations are needed
to determine pack size. Neighboring wolf packs that do not have
collared individuals are often located, mapped, and counted. Thus
fairly large areas can be censused for wolf abundance. Radio-telemetry
can also give biologists an estimate of wolf mortality, territory
size, dispersal rates, and the number and type of prey being consumed.
The reliability of these estimates is related to the number of wolves
and wolf packs collared as well as the number of times they are
located and accurately counted.
Radio-telemetry is the ultimate method, but other techniques are
used to estimate wolf population size and trends. For example, computer
modeling is sometimes used to project baseline estimates that were
originally determined from radio-telemetry. This helps keep estimates
current but side-steps the continual need for expensive and time
consuming radio-collaring studies. In large areas, such as an entire
state, it is not feasible to radio-collar a wolf in every pack.
In these cases population trend surveys are often used. Trend surveys
include: ground and aerial tracking for wolf sign in snow, counting
visits to scent stations, soliciting responses to simulated howling,
interviewing hunters, trappers and resource professionals, and keeping
track of depredation complaints.
Wolf abundance and distribution are monitored annually by the
Wisconsin and Michigan Departments of Natural Resources. Both states
use a mix of radio-telemetry and surveys for sign and incidental
observations.
The Minnesota Department of Natural Resources (MN DNR) uses a method
of estimating state-wide abundance which incorporates surveys of
wolf sign (questionnaires to resource professionals, scent stations,
and depredation complaints) from across the state combined with
intensive radio-telemetry studies in smaller areas. MN DNR used
this method to obtain state-wide wolf population estimates of 1,235
during the winter of 1978-79 and 1,500 - 1,750 during the winter
of 1988-89. The 1988-89 estimate was expanded to 2,000 - 2,200 in
1996 using population modeling combined with new estimates of wolf
range, recruitment, and mortality. MN DNR's 1997-98 state-wide survey/census,
a technically advanced version of previous techniques, estimates
MN wolf population to be 2,450 wolves and was used again in 2004-2005 with
an estimate of 3,020 wolves.
Fuller, T.K., W.E. Berg, G.L. Radde, M.S. Lenarz, and G.B. Joselyn.
1992. A history and current estimate of wolf distribution and abundance
in Minnesota. Wildlife Society Bulletin, Volume 20, pages 42 - 55.
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