Mother-calf relationships and maternal investment in European bisonBison bonasus

Mother-young relationships, up to the third month of the calves’ life, were investigated in European bisonBison bonasus (Linnaeus, 1758) from Białowieża National Park breeding centres (Poland). During the first week, calves spent most of their time close to their mothers and were rarely seen in the vicinity of other group members. Highest suckling rate, most frequent vocal contact and agonistic behaviour of mothers towards intruders, were other characteristics of this period. Although being a forest species, European bison exhibit a following type of strategy for offspring protection, typical for ungulates living in open areas; no hiding phase was observed. Suckling rates were similar in calves of both sexes, however, the pattern of nursing was different: male calves suckled longer, but in rarer bouts than female calves. The mothers’ condition, reflected by their social rank, did not influence the suckling rate. No sex differences were recorded in other maternal activities or mother-calf distance. The presumption of a lack of sex-biased maternal investment in European bison is confirmed by the results of other research.