Distance rules for minimum counts of Eurasian lynx Lynx lynx family groups under different ecological conditions
John D. C. Linnell, John Odden, Henrik Andrén, Olof Liberg, Reidar Andersen, Pål Moa, Tor Kvam, Henrik Brøseth, Peter Segerström, Per Ahlqvist, Krzysztof Schmidt, W?odzimierz J?drzejewski & Henryk Okarma
Linnell, J.D.C., Odden, J., Andre´n, H., Liberg, O., Andersen, R., Moa, P., Kvam, T., Brøseth, H., Segerström, P., Ahlqvist, P., Schmidt, K., J?drzejewski, W.& Okarma, H. 2007: Distance rules for minimum counts of Eurasian lynx Lynx lynx family groups under different ecological conditions. - Wildl. Biol. 13: 447-455.
Monitoring of lynx Lynx lynx populations in Scandinavia is largely based around unreplicated minimum counts of family groups, i.e. adult females with dependent kittens. When observations cannot be separated from each other on the basis of back-tracking in the snow it is desirable to use a distance rule to separate observations of groups that are so far apart that they are unlikely to be derived from the same group. We have analysed radio-telemetry derived movement data from five study areas, corresponding to three ecologically different regions, in Scandinavia, and included data from Poland for comparison. We derive examples of two different distance rules; one is a static rule based on home-range size and length which is suitable for observations accumulated during a whole winter, and the other is a dynamic rule suitable for observations collected within 1-7 days of each other. Because of inter-study area variation in home-range size and movement there is a need to use different rules in different regions. Within Scandinavia, average maximum home-range lengths varied from 28 to 54 km, and average maximum daily distances travelled varied from eight to 16 km in the three regions. This implies that locally collected movement data are a prerequisite for application of this type of methodology.
Key words: census, Eurasian lynx, home range, large carnivore, Lynx lynx, monitoring, movement
John D.C. Linnell, John Odden, Reidar Andersen* & Henrik Brøseth, Norwegian Institute for Nature Research, Tungasletta 2, NO-7485 Trondheim, Norway - e-mail addresses: john.linnell@nina.no (John D.C. Linnell); john.odden@nina.no (John Odden); reidar.andersen@vm.ntnu.no (Reidar Andersen);
henrik.broseth@nina.no (Henrik Brøseth)
Henrik Andrén, Olof Liberg & Per Ahlqvist, Grimsö Wildlife Research Station, Department of Conservation Biology, Swedish University of Agricultural Sciences, SE-73091Riddarhyttan, Sweden - e-mail addresses: henrik.andren@nvb.slu.se (Henrik Andrén); olof.liberg@nvb.slu.se (Olof Liberg); Per.Ahlqvist@nvb.slu.se (Per Ahlqvist)
Pål Moa & Tor Kvam, Department of Resource Sciences, North-Trøndelag College,Box145,NO-7702 Steinkjer, Norway - e-mail addresses: pal.f.moa@hint.no (Pål Moa); tor.kvam@hint.no (Tor Kvam)
Peter Segerström, Vaikijaur 617, SE-962 99 Jokkmokk, Sweden - e-mail: peter@solbritt.se
Krzysztof Schmidt & W?odzimierz J?drzejewski, Mammal Research Institute, Polish Academy of Sciences, PL-17-230 Bia?owie?a, Poland - e-mail addresses: kschmidt@bison.zbs.bialovieza.pl (Krzysztof Schmidt); wjedrzej@bison.zbs.bialovieza.pl (W?odzimierz J?drzejewski)
Henryk Okarma, Institute for Nature Conservation, Polish Academy of Sciences, PL-31-120 Krakow, Poland - e-mail: okarma@iop.krakow.pl
*Present address: Reidar Andersen, Department of Zoology, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
Corresponding author: John D.C. Linnell
Received 26 March 2004, accepted 10 September 2007
Associate Editor: Urs Breitenmoser