The black flying-fox (Pteropus alecto) in north Australia: juvenile mortality and longevity

Abstract

Mortality rates for juvenile black flying-fox (Pteropus alecto) are presented from data collected in the Northern Territory of Australia (12˚24′–13˚03′S) between 1992 and 1998. Forearm size data were used to construct a two-stage life table for each sex. Mortality rates from birth to adult size (170 mm) varied between sexes, between camp-sites and between years, and ranged from 0.43 to 0.80. Overall, the mortality rates from birth to adult size were 0.70 for females (n = 846) and 0.63 for males (n = 990). These rates represent annual juvenile mortality rates of 0.57 for females and 0.47 for males, given that females reach adult size at 14.8 months of age and males at 16.3 months of age. The maximum age of P. alecto recorded in this study was 4.5 years. The mean lifespan of females reaching adulthood would need to be seven years for a stable population size to be maintained, but may be shorter given that the mortality rates may have been over-estimated. The mortality rates and lifespan of P. alecto are not unusual amongst Chiroptera or small mammals in general.