First breeding age in captive and wild Bearded Vultures Gypaetus barbatus

Abstract

We present data on the age of first breeding in captive and wild Bearded Vultures. The mean age of first breeding (egg-laying) in the captive population was 7.7 years for females and 8.9 for males. The first offspring was raised on average by 8.3-year-old females and 9.7-year-old males. In wild Bearded Vultures, first-time-paired and territorial individuals were recorded when they were 6.5 years old, on average. The mean age of first breeding was 8.1 years, whereas the mean age of first successful breeding was 11.4. Paired females were recorded at the age of 6.5 years and breeding at 6, whereas the youngest recorded paired males were 6.4 years old and breeding at 7. 39.5% of the marked birds alive over 6 years were recorded as not yet territorial, suggesting the existence of a substantial fraction of adult floaters without breeding territories. Pyrenean Bearded Vultures are characterized by delayed reproduction, with the first breeding attempt taking place well after the acquisition of full adult plumage. We discuss whether deferred breeding in this increasing population could be explained by the increase in density and/or mortality rate in the younger age groups, which could affect the age of maturity.