Eurasian lynx (Lynx Lynx) population sizes estimated by the snow-track counting method in Western Uusimaa

Counting of the snow tracks of lynx (Lynx lynx) and wolf (Canis lupus) took place in Western Uusimaa, southern Finland, on January 2 2010 for the purpose of obtaining more reliable information about the numbers of these species. A further goal was to develop methodology to support the current observation system and to improve the validity of density estimates for large carnivores.

About 1,000 hunters from 130 hunting clubs searched for the tracks over an area covering 4,827 km2, combing the area slowly along designated routes. The combined length of the routes was 5,096 km (average 1.06 km/km2). Upon discovering a carnivore track, the species, number of individuals and direction of travel were recorded. Overlap between lynx litter observations was eliminated as carefully as possible.

At least 19 separate litters were found, with approximately 1 to 5 litters undetected. The size of the Western Uusimaa lynx population was estimated at 110 - 155 animals. A single, unverified wolf track was observed. Of the 427 lynx track observations, around 26% were connected to the litters. All litter tracks and 16% of individual track observations were verified by independent track experts. The hunters were excellent in recognising the lynx tracks; only two of the individual track observations and five of the litters track observations were rejected in the verification process. Geographically, both individual and litter track observations were rather regularly distributed. The average distance between litters was 11 km, with 1.7 kittens per litter on average.

The counting method used gave the most reliable estimate so far of the size of the Western Uusimaa lynx population. However, the need remains for further development in terms of organisation, process and analyses. The collection of more reliable and simultaneous information on the daily movements of carnivores within the counting area is a key future requirement for reaching a still more precise estimate of population size. Precision in litter observation should also be further improved.

Siira, A., Laulumaa, M., Eronen, V., Holmala, K., Heikkinen, S. & Kojola, I. 2010. Eurasian lynx Lynx Lynx population sizes estimated by the snow-track counting method in Western Uusimaa - LUMI 2010. Riista- ja kalatalous – Selvityksiä 9/2010. 27 p.