SEX-SPECIFIC SURVIVAL RATES IN BIRDS

The hypothesis of higher survival rates in bird males than those of fe males was tested. Annual survival rates for both sexes in 10 species w ere estimated using the stochastic models. In 8 species survival of ma les was higher than that of the females, although significant differen ces were found in two species only. The analysis of published data alo ng with our results (109 data sets representing 70 species from 12 ord ers) show that the higher survival rates of males are significantly mo re frequent than in females (80 cases out of 109 sets). The widespread concept of higher mortality of male sex in animals, therefore, is not supported by the data on birds.