Misplaced ‘vulture restaurants’ may harm Canarian ground-nesting birds

The Canary Islands sound very interesting. You can access some GIS data via Google Earth, thanks to the Canary Islands Spatial Data Infrastructure.

As well as 50% of their vertebrate species (Juan et al., 2000), 21 non-migratory vertebrate species, and 7 birds (Blanco and Gonzalez, 2002), endemic fauna of the Canary Islands include 5 bird of prey subspecies: the Canarian Egyptian Vulture (or Guirre), a Common Buzzard, a Eurasian Sparrowhawk, two Eurasian Kestrel subspecies, and a Barn Owl. The Islands are also home to Barbary Falcons and Ospreys (Palacios, 2004).

The Canarian Egyptian Vulture is an endangered bird now restricted largely to Fuerteventura and to two territories on Lanzarote. The subspecies declined rapidly due to collisions with power lines, poisoning, and increased tourism, and in 2000 there was estimated to be only 25-30 breeding pairs (Donázar et al., 2002).

The European Commission’s LIFE (Financial Instrument for the Environment) project for Spain planned to introduce measures to protect the Canarian Egyptian vulture by October 2009:

A 50% reduction in the adult mortality through collision with power lines will be attained by introducing corrective measures in the island’s power lines. An increase of 20% in the breeding success will be achieved through reinforced surveillance of nesting areas. Surveillance and awareness raising measures will be implemented with the aim to reduce the use of poison. Finally, to avoid the potential threat of famines, three controlled middens will be created with the collaboration of local livestock breeders.

Middens are also known as ‘vulture restaurants’, and are basically areas with a constant supply of carcasses (provided by humans) so food availability for the birds is never erratic. This would hopefully encourage breeding and improve survival, thereby increasing the number of birds and helping to establish a sustainable population. Sounds like a great example of a simple and easily implemented conservation method, right?

Sort of.

In an article in this January’s Animal Conservation by a team from CSIC (Spanish National Research Council) including a member of the team that originally described the species in the first place (Donázar et al., 2002), it was found that, when artificial ground-nesting birds‘ nests were placed along lines 200m to 34km from vulture restaurants (as summarised on Nature Data) “of the 67% lines predated by carrion-eaters, 90% of nests were attacked.”

It’s never simple, is it?

At least it’s predictably never simple. The complexities of population dynamics are mind-blowing, but by anticipating that there are complexities and learning more about the ecosystems, reserve management continually gets more effective.

References:

Blanco JC, Gonzalez JL, 1992. “Libro rojo de los vertebrados de Espana.” (Red List of the vertebrates of Spain) Ministerio de Agricultura, Pesca y Alimentacion, Madrid, Spain. (via Donázar, 2002)

Cortés-Avizanda A, Carrete M, Serrano D, Donázar JA, 2009. “Carcasses increase the probability of predation of ground-nesting birds: a caveat regarding the conservation value of vulture restaurants.” Animal Conservation, 12(1): 85-88, doi: 10.1111/j.1469-1795.2008.00231.x (CSIC, full pdf here)

Donázar JA, Negro JJ, Palacios CJ, Gangoso L, Godoy JA, Ceballos O, Hiraldo F, Capote N, 2002. “Description of a new subspecies of the Egyptian Vulture (Accipitridae: Neophron percnopterus) from the Canary Islands.” Journal of Raptor Research 36(1): 17–23 (CSIC, full pdf here)

Juan C, Emerson BC, Oromí P, Hewitt GM, 2000. “Colonization and diversification: towards a phylogeographic synthesis for the Canary Islands.” Trends in Ecology and Evolution 15: 104-109, doi: 10.1016/S0169-5347(99)01776-0 (Universitat de les Illes Balears)

Palacios JC, 2004. “Current status and distribution of birds of prey in the Canary Islands.” Bird Conservation International, 14:3:203-213, doi: 10.1017/S0959270904000255 (CSIC)