THE ROLES OF PREDATION, SNOW COVER, ACORN CROP, AND MAN-RELATED FACTORS ON UNGULATE MORTALITY IN BIALOWIEZA PRIMEVAL FOREST, POLAND

The relative importance of various mortality factors was studied in po pulations of European bison Bison bonasus, moose Alces alces, red deer Cervus elaphus, roe deer Capreolus capreolus, and wild boar Sus scrof a in the exploited and protected parts of Bialowieza Primeval Forest, eastern Poland. Data consisted of harvest quotas and records of ungula te carcasses found to have died from poaching, gun-wounds, traffic acc idents, disease/starvation, and killed by wolves Canis lupus, lynx Lyn x lynx and stray dogs. In the exploited forests, red deer suffered mos t from wolf predation (cause of death in 58% of deer carcasses found) and disease/starvation (22%). Important factors of roe deer mortality were disease/starvation (31% of carcasses), lynx (28%), and wolves (23 %). European bison and moose died mainly from disease (79% and 52%, re spectively), and poaching (14% and 32%, respectively). Wild boar suffe red mostly from disease/starvation (61%) and wolf predation (16%). Hun ters, poachers, and traffic accidents acted non-selectively on the 5 u ngulate species and on the sex and age classes. Wolves positively sele cted red deer and took fewer wild boar than expected at random. Lynx s pecialised on roe deer, and stray dogs killed wild boar more often tha n expected. Lynx strongly selected red deer calves. Stray dogs killed more juvenile roe deer than expected. In wild boar, mortality from sta rvation/disease increased in the year following an abundant acorn crop . Heavy acorn crop led to an increase in the numbers of wild boar, man y of which died the following year. In the other ungulates, variation in acorn crop had no effect on death from starvation and disease. Vari ation in snow cover did not affect ungulate mortality in mild and mode rate winters, but the extremely severe winter of 1969/70 (snow depth u p to 100 cm) caused mass deaths of red deer, roe deer and wild boar.