Birth and mortality rate of European Bison (Bison bonasus bonasus L1758) population

A survey of the birth and mortality of European Bison (Bison bonasus bonasus L1758) conducted from 2000 to 2018 in two nurseries showed that the females in the first study group had the first mating at an average age of 42.54 months, with an interval from 23 to 84.5 months. The average age of the first mated females in the second study group was 31.67 months, with an interval from 39.5 to 66.93 months. The average time between calving for the first group females was 9.95 months, with an interval from 0.5 to 28.5 months. The calving interval for the second group was 8.53 months with variation from 1 to 32 months. The first group had a maximum of seven calves, while the maximum in the second group was 13.A total of 33 calves were born in the first group during the study period, 16 males (48.48%) and 17 females (51.51%), while 40 calves were born in the second group,16 males (40.0%) and 24 females (60.0%).The mortality rate in the first group ranged between 14.3 and 30.0%, with a mortality rate of males of 20 to 60% and for females of 16.66 to 50%. In the second group, the mortality rate was from 9.09 to 23.08%, for males 33.33% and from 11.11 to 25.0% for females. The results indicate that future studies should address greater attention to birth and mortality rates.