Vulture populations are experiencing rapid declines in many parts of the globe, perhaps currently more marked in Africa then elsewhere. In a recently published paper, Jack Thorley and Tim Clutton-Brock document a medium-term decline in the African White-backed Vulture Gyps africanus population inhabiting the southern Kalahari, South Africa, using a long-term behavioural data set collected from a habituated population of meerkats Suricata suricatta.
Living in open environments exposes meerkats to aerial and terrestrial predators. Meerkats mitigate this problem by exhibiting sentinel behaviour, wherein individuals periodically forgo foraging activities to scan the sky and ground for possible threats, at which point they emit alarm calls to inform the group. These calls vary according to the location (aerial or terrestrial) and urgency of the threat being posed.
Vultures, although posing no threat to meerkats, also reliably elicit a ‘low urgency, aerial threat’ call and a coordinated group response. Therefore, the rate at which human observers note the response of meerkat groups to a vulture-induced alarm call acts as a good proxy for vulture abundance.
Although unconventional, this sampling method uncovered a steady decline over 17 years in White-backed Vulture numbers – a 3.49% annual rate of decline -, that mirrors the temporal decline recently documented through direct vulture monitoring in other southern African populations over three decades.
The authors therefore used Meerkat behaviour to document a vulture decline in a region of South Africa.
You can download this interesting paper below.
Photo: André Botha