In southern Africa the bearded vulture occurs in the Maloti-Drakensberg Mountain range in South Africa and Lesotho, and is represented by a different subspecies (Gypaetus barbatus meridionalis) from the Eurasian bearded vulture. It is a geographically isolated population, which has declined in distribution and density in the past few decades. As a result, the species has been up-listed regionally to Critically Endangered, indicating that it faces an extremely high risk of extinction in the wild, as a result of a reduction in population size and geographic range, and the continuing threats to the species.
A new research paper on the reproductive output of this population, which has been closely monitored, has been recently published. The authors analysed all reproductive data from 2000 to 2016 (a total of more than 100 breeding territories) to determine whether the birds attempted to breed every year, and also the respective breeding success, in order to try to establish if productivity may be currently limiting population growth.
Their analysis found that on average the bearded vultures breed only every second year, and only successfully in 3/4 of the breeding attempts. The overall productivity is recorded as 0.42 young per pair and per year, and is lower than what was found in previous studies - worrisome for an already small population.
This productivity is slightly higher than the productivity in the Pyrenees and Crete, but lower than in the Alps.
The authors also examined the potential factors for this decline and found that it is unlikely that it is related with food shortages – increased mortality due to human poisoning is the probable culprit.
You can download the article below.
Photo: Sonja Krueger