By Keith L. Bildstein, Ph.D., Sarkis Acopian Director of Conservation Science
Hawk Mountain Sanctuary
12 December 2016
We typically characterize vultures as gluttonous creatures, obligate scavenging birds of prey that engage in rough-and tumble feeding frenzies at large ungulate and pachyderm carcasses in the company of dozens of other “all consuming” vultures, scarfing up enough meat to last for several days. And indeed, vultures sometimes eat so much food that they remain grounded for an hour or more after feeding for partial digestion to take place, before they are light enough to take off. Having watched these birds feed for many years, I can tell you that all of this is true. But watching vultures at so-called “vulture restaurants,” where humans routinely provide food, sheds light on an aspect of vulture feeding that goes largely unrecognized by the general public.
In fact, some vultures are “finicky” as well as “voracious,” feeders; especially at vulture restaurants where daily meals are typical. The world’s first vulture restaurant, in the Drakensburg Mountains of South Africa opened in the 1960s to help supplement the diets of local Bearded Vultures. Today, vultures restaurants (bird feeders for vultures, if you will) are used to provide “clean,” lead-free meat to recently released California Condors in the American West. Many of the restaurants are associated with ecotourism, serving a useful purpose in bringing vultures and people together. One such restaurant at the Hoedspruit Endangered Species Centre near Kruger National Park in northeastern South Africa has been feeding wild vultures and other scavenging birds for more than 30 years. The restaurant works well at attracting handfuls of Pied Crows and Black Kites, dozens of Marabou Storks and Hooded Vultures, and hundreds of African White-backed Vultures, the latter two of which are now Critically Endangered.
Earlier this month, University of KwaZulu-Natal post-doctoral student and Hawk Mountain research associate, Dr. Lindy Thompson, and I spent four days at the Centre near Hoedspruit trying to catch Hooded Vultures. During that time we learned a lot about the finicky feeding behavior of the birds. Our goal was simple enough: catch as many as three of the Hooded Vultures visiting the restaurant, and fit them with satellite-tracking devices that would allow us to monitor the movement ecology of the species, including information on how dependent individuals were on vulture restaurants in the region versus how much time they spent in the nearby Kruger National Park feeding on native wildlife, and how they interacted with other species in the region.
We already had caught and fitted 10 Hooded Vultures with tracking devices in South Africa, and two of our previously tagged birds actually showed up at the restaurant during our four days of observation, even though neither has been tagged there. One of the two, Don King, had been caught at a private nature reserve 45 miles north of the Hoedspruit restaurant in February of 2016. Don looked healthy enough, although he had lost his downy top-knot that led to its name. The second tagged bird, Mopane, had been caught in Kruger National Park about 60 miles northeast of the restaurant in August of 2014. It, too, looked quite healthy.
The two marked birds were joined by about 30 unmarked individuals that visited the restaurant daily. Unfortunately we were unable to capture any of them. We did snare several of the far larger African White-backed Vultures that clearly dominated the smaller “hoodies” at the restaurant’s offerings. Hooded Vultures, it turns out, are finicky feeders when feeding in the company of White-backed Vultures, pecking at and gleaning only tiny scraps of meat with their small, thin bills, after the meat had been torn apart by the larger white backs during feeding frenzies. By the time the hoodies got close enough to our traps, the snares we had set already had been pulled closed by the white-backs, making capturing the former all-but-impossible.
Lindy Thompson and Andre Botha of the South African Endangered Wildlife Trust will try to capture the hoodies at other feeding sites that attract fewer white backs. Older elephant carcasses work well for this purpose, as they often continue to be visited by the more fastidious hoodies for several days after larger vultures, hyenas, and jackals have stripped most of the flesh from carcass.
The finicky feeding behavior of hoodies is well known among those of us that study the birds. It appears that hoodies have instituted their own specialized feeding niche, one that involves “cleaning up” after the larger and less finicky species. Although this makes hoodies a bit more difficult to capture, it is somewhat endearing as well. As I see it, a vulture that cleans up after other vultures can’t help but be appreciated.