Three approaches to estimate wolf Canis lupus predation rates on moose Alces alces populations
Gundersen, Hege; Solberg, Erling J.; Wabakken, Petter; Storaas, Torstein; Zimmermann, Barbara; Andreassen, Harry Peter
Peer reviewed
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http://hdl.handle.net/11250/134148Utgivelsesdato
2008Metadata
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Originalversjon
Gundersen, H., Solberg, E.J., Wabakken, P., Storaas, T., Zimmermann, B., Andreassen, H.P. (2008) Three approaches to estimate wolf Canis lupus predation rates on moose Alces alces populations. European Journal of Wildlife Research, 54(2), 335-346Sammendrag
Abstract We employed three different methods to estimate
predation rates on moose in a newly colonized wolf
territory in Norway. In the first two methods, we estimated
predation rates based on the difference in calf/cow ratios
outside and inside the wolf pack territory from (1) hunter
observations and (2) aerial surveys. In the last method, (3)
we estimated loss of calves of radio-collared cows inside
and outside the wolf pack territory. The difference in
mortality rates estimated between the area subject to
predation and the area outside the wolf pack territory
essentially constitutes the additive component of predation.
We also tested the sensitivity of violating the assumptions
of methods 1 and 2 related to equal fecundity and mortality
because of other factors than predation inside and outside
the wolf pack territory. Predation rates varied considerably
between years and methods used, with hunter observations
(method 1) giving the lowest and aerial surveys (method 2)
giving the highest estimates. Method 3 (radio telemetry)
was the most direct assessment of predation and probably the best approach to estimate predation rates in moose.
However, all three methods show the same yearly changes
and may therefore be appropriate to question trends trough
time or between areas.