Snow track counts in 2008

20 years ago the wildlife triangle counts were developed by FGFRI in cooperation with the Hunters’ Central Organization. Wildlife triangles provide annually reliable information on abundance levels and changes of some 30 wildlife species. A wildlife triangle is an equilateral triangle with a perimeter of 12 kilometres. A total of more than 1,700 wildlife triangles have been established in Finland, but in the winter of 2008 counts were carried out on slightly more than 600 of these.

During the winter census, the tracks of mammals crossing the triangle line are recorded, as are observations of grouse, common raven (Corvus corax) and northern goshawk (Accipiter gentilis). One to three days before the count, old tracks crossing the line are either recorded or covered. Sometimes the count is carried out shortly after a heavy snowfall that covers old tracks. The accumulation time for the tracks is taken into account in the track density calculations. Track density is given as the ratio of tracks crossing per 10 kilometres of triangle line for every 24 hours. The abundance of birds is given as observed birds per 10 kilometres of triangle.

A second winter with poor snow conditions

As in the previous year, the winter of 2007/2008 was very mild, and especially in southern Finland, there was very little snow (Fig. 1). In most parts of Finland, the average seasonal temperature was the highest that had been recorded in a century. Snow cover was average in Lapland and the Kainuu area, but in other parts of the country there was very little snow, with almost none in the southern and southwestern coastal area. During the time of year when key censusing was set to take place, only the northeastern side of the Joensuu-Iisalmi-Tornio line was considered to have adequate (over 25 cm) snow cover.

Figure 1. Depth of snow cover (Finnish Meteorological Institute) on 15 January, 15 February and 15 March in the winter of 2008.

Because of the warm winter, snow track counts were carried out under very difficult conditions. On the southern coast, only a handful of possible censusing days presented themselves. In northern and eastern Finland, snow conditions were average and thus adequate for censusing, but far from ideal.

Track densities are average

Difficult weather conditions had an impact on the number of censused triangles last year. During 2001-2006 the number of censused triangles had stabilized at about 750, but last year’s number of 627 was well below this, even if it was a slight improvement on the previous year’s 606.

Figure 2. The number and dates of triangles censused in the winter of 2008, by game district.

The 2008 snow track census recorded 37,100 snow tracks of mammals from 23 species. Observations of almost 5,800 birds (grouse, goshawks and ravens) were also made. The track density of all species was significantly higher than in the winter of 2007. Nine of the ten most numerous species had a higher track density than the previous year, and even the tenth species had a track density only slightly lower than last year. The averages for the whole country were more than 40% higher than last year for squirrels, mountain hares, European hares and wild forest reindeer. Compared with the whole 20-year monitoring period, however, track densities were considered average. Five of the ten most numerous species had a higher track density than the long term average (European lynx, white-tailed deer, European hare, European roe deer, and squirrel), and five had lower densities (pine marten, moose, mountain hare, fox, and ermine).

Scientist in charge of project

Pekka Helle
Oulu Game and Fisheries Research
Tutkijantie 2 E
FI-90570 Oulu, Finland
Phone +35820 575 1410
E-mail: firstname.lastname@rktl.fi

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