Population dynamics of Wolves Canis lupus in Bialowieża Primeval Forest (Poland and Belarus) in relation to hunting by humans, 1847–1993

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Abstract

Population dynamics and demography of the Wolf Canis lupus were studied in Bialowieza Primeval Forest (BPF, 1250 km2), the best preserved mixed and deciduous forest in the lowlands of Europe; 40% of BPF belongs to Poland and 60% to the Belarus Republic. Polish and Belarussian game departments' inventories of Wolf numbers (1946-93), archival hunting statistics (1847–1993), observations, snowtracking and reports on shot Wolves (1980-93) are presented. In BPF, Wolves coexist with five species of ungulates: European Bison Bison bonasus. Moose Alces alces, Red Deer Cervus elaphus, Roe Deer Capreolus capreolus and Wild Boar Sus scrofa.

During the last 150 years, there were four periods with high numbers of Wolves in BPF: around 1820-40, 1870-80, 1925-30 and 1945-48, always after uprisings and wars. Maximally, from 7.2 to 9.1 ind./100 km2 were recorded. Declines and prolonged periods of low numbers of Wolves (due to persecution by humans) were recorded in 1882–1915 and 1958-72 (0–1 ind./100 km2).

In recent years (1980-93), there were on average 33 Wolves in BPF (2.6 ind./lOO km2) and their numbers were slowly increasing. Data from this period were subject to a demographic analysis of the Wolf population. In the Polish part of BPF (on average, 13 Wolves recorded every year), negligible hunting occurred in 1980-89, and since 1989 Wolves have been protected. In the Belarussian part, Wolves were treated as pests, and every year 16 Wolves were shot out of the mean number of 20 individuals recorded (80%). Most of the killed Wolves (70% of harvest) were shot in December, January and February, during traditional snowtracking-driving hunts with ‘fladry’ (lines of flags).

Hunting in the Belarussian part of BPF caused a decline in pack size from an average of 4.0 (SD 2.0) in late autumn, to 3.6 (SD 1.6) in mid winter, to 2.3 (SD 1.5) in late winter. In the Polish part (no hunting), the pack size varied from 4.2 (SD 1.7) in the late autumn, 4.3 (SD 2.2) in mid winter, to 3.6 (SD 1.9) in the late winter. Among Wolves shot, 44% were females and 56% were males (ratio 1: 1.3). The age of 63 shot Wolves was estimated by external features; 35% were juveniles < 1 year, 43% were 2–3 years old, and 22% were 4–5 years' old. In 1980-93, in the whole BPF, legal hunting accounted for 78% of Wolf mortality, taking pups from their natal dens by humans 16%, poaching 4%, traffic accidents < 1%, and unknown causes 1%. Sarcoptic mange was recorded in several shot Wolves.

On average, 6.25 pups per litter were born (range 3–8). If only natural factors of mortality are considered, 3 months after birth the mean litter size was 3.1 (50% mortality), and 2.2 pups per litter would reach 1 year of age (65% of mortality). However, 29% of all recorded pups were taken by humans for pets (in both the Polish and Belarussian parts of BPF) or to receive a bounty (in the Belarussian part). As early as November, juveniles along with adults are subject to hunting in the Belarussian part. Thus, if both natural and human-caused mortality is considered, 2.2 pups per litter survived 3 months (65% mortality) and only 0.9 pup per litter reached 1 year of age (85% mortality).

In 1980-93, the Bialowieia population of Wolves survived and increased, most probably due to a constant immigration of Wolves (on average, two immigrants per year) from the vast forests adjoining BPF to the east.

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