Factors shaping population densities and increase rates of ungulates in Bialowieza Primeval Forest (Poland and Belarus) in the 19th and 20th centuries

Population dynamics of ungulates (European bison Bison bonasus, elk Alces alces, red deer Ceruus ela.ph.us, roe deer Capreolus capreolus, wild boar Sus scrofa, non-native fallow deer Dama dama, and cattle) were analysed in the Białowieża Primeval Forest (BPF, 1250 km2), one of the largest remaining tracts of ancient mixed and deciduous forests in the lowlands of Europe. Forty percent of BPF belongs to Poland, and 60% to the Belarus Republic. Polish and Betarussian game departments inventories of ungulate numbers (1946-1993) and archival data on censuses and hunting statistics (1798-1940) are presented. The recorded ranges of densities of native wild ungutates were: European bison 0-1.5 inds/km2, elk 0-0.6, red deer 0-5.4, roe deer 0.6-4.8, and wild boar 0.2-3.8 inds/km2. Fallow deer were introduced in 1890 (maximum density reached in 1914 was 1.2 inds/km2) and were eradicated by 1920. Cattle were traditionally pastured in the Forest, and its grazing impact was heaviest in 1880-1914 (maximum recorded density 6.7 inds/km2). In 1798-1993, the community of wild ungulates consisted of three to six species, with total densities varying from < 2 to 14.4 inds/km2 (65 to 1180 kg of crude biomass per 1 km2). Roe deer, wild boar, and red deer were usually the dominants. However, in 1860-1971, cattle constituted from 15% to 80% by numbers and from 37% to 87% by biomass of all ungulates in Białowieża Forest. Data on population trends within a five-species assemblage of native wild ungu­lates were subject to multiple regression analysis to determine the roles of predation (by wolves Canis lupus and lynxes Lynx lynx), competition, food, weather variables, and humans in shaping population densities and increase rates of ungulates. Growth of the mean annual temperature had positive effect on densities of all ungulates, probably through improving food supply and feeding conditions. Bison and elk were shaped by intra- and interspecific competition for food. Bison numbers have heen significantly limited by humans, due to both uncontrolled exploitation in years of political instability and deliberate culling in years of protection. Red deer and roe deer were primarily shaped by predation from wolves and lynx, respectively. Compe­tition for food influenced red and roe deer when they had erupted after predator extermination. Wild boar was influenced predominantly by food availability, especially the highly variable crops of oak seeds.