Long term link between the food diet and the breeding success in a declining population of Egyptian vultures.
Between 2000 and 2009, a study was carried out in Andalusia, southern Spain, whose aim was to analyse the productivity and food habits of Egyptian vultures in 13 territories. The annual 3.4 % decline of the inhabited territories is alarming. In less than a decade, the number of inhabited territories went down from 33 to 23 over the 170 000 km2 studied zone.
Study area and location of breeding territories of Egyptian vultures according to the three zones considered.
Two specific objectives :
- Describe the diet composition and its variation in connection with the local environmental variability
- Verify the link between the breeding parameters and food availability
Method and results :
The team collected the remains of preys in nests between June and July, which is when the juveniles are ringed, in order to analyse the birds diet. They identified 1071 remains of prey.
The team found a positive link between productivity (number of fledged birds/number of studied birds) and food diversity. These results confirm similar studies about generalist predators or scavengers such as golden eagles or bearded vultures.
Variation in productivity (solid line) and diet size (dotted line)
In an area with six feeding stations, the diet of Egyptian vultures is mainly composed of rabbits, reptiles and small or medium-sized vertebrates. This means that the lack of food, which results from restrictions imposed by the sanitary regulation, is probably less damaging to breeding and population dynamics than it is for other scavengers.
Translated by Claudine Caillet