Talk on Vultures in KZN

Oct 08, 2015 No Comments by

Dr Sonja Kruger will present a lecture entitled “The Decline of the Bearded Vulture Gypaetus barbatus in Southern Africa” on 14th October (see time and venue below)
The Bearded Vulture Gypaetus barbatus is a Critically Endangered species in southern Africa, whose entire range in the southern hemisphere falls within the Maloti-Drakensberg mountain range of South Africa and Lesotho. Dr Kruger synthesized 15 years of research on the Bearded Vulture population to quantify the decline, to investigate the mechanisms of the decline and to determine the most appropriate management actions to target a positive population growth rate.
Dr Kruger assessed territory occupancy, distribution and density of the population. The number of occupied territories decreased by between 32-51%, the breeding range decreased by 27% and breeding densities decreased by 20% over five decades. The birds occupy a breeding range of 28,125 km2 and the population is estimated at between 368-408 individuals (109-221 breeding pairs).
Three hypotheses were then examined in an attempt to explain which factors were associated with territories recorded as abandoned; these related to human impact, food availability and climate change. The strongest support was for the human impact hypothesis, with abandonment more likely in territories with higher densities of power lines and human settlements. These findings agreed with the main causes of mortality.
The overall foraging range of the population was 51,767 km2 with adults focussing their activities in an area around their nests. Non-adults increased the size of their range with age, with birds of 4-6 years facing the greatest exposure to risk factors.
The genetic risk was examined by sampling two populations in sub-Saharan Africa. Results showed little to no differentiation between populations, suggesting that translocations of individuals from Ethiopia could be considered for introduction into the local population.
Dr Kruger’s models predicted a negative growth rate for the population over the next 50 years (λ=0.99) with a high probability (0.89) of extinction as a result of low survival estimates and reduced productivity. Human activities and power line collisions were the primary reasons for the low survival rates with poisoning alone accounting for 90% of the deaths. To achieve a positive growth rate, mortality rates should be reduced by >50%, productivity increased by >25% and the population should be supplemented by at least six individuals annually for the next 20 years.
Dr Kruger obtained her BSc, Honours and MSc at the University of Natal, Pietermaritzburg and her PhD at the University of Cape Town. She is employed as the Ecologist for the Drakensberg by Ezemvelo KwaZulu-Natal Wildlife.
Currently, Dr Kruger is responsible for providing effective ecological advice to address biodiversity conservation issues, which is an integral component of management and decision making. She develops, implements, coordinates and conducts several research projects and monitors programmes to address priority information needs. Dr Kruger also contributes to the Integrated Management Planning Process by providing input and commenting on development applications on State and on private land, and producing scoping reports for various developments in protected areas.

Wednesday, 14 October 2015
Time: 5.45 pm
Venue: John Bews Lecture Theatre,
Life Sciences Campus, Carbis Road, Pietermaritzburg.

All welcome. Light refreshments will be supplied.
Enquiries: Prof. Mike Perrin, Tel. 033 – 260 5118 / 5435.

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