Rocky Canyons Research Articles

BREEDING AND FEEDING HABITS OF THE BLACK WHEATEAROENANTHE LEUCURAIN SOUTHERN SPAIN

SUMMARYThe breeding and feeding habits of the Black WheatearO. leucurawere studied in an arid, rocky canyon region near Almería in southeastern Spain from October 1961 to May 1962. Strict territoriality appears to be absent in the species except around nesting sites and birds foraged in extensive and overlapping areas without intraspecific reactions. The rock‐carrying habit of the species is its most unusual characteristic. Great numbers of rocks, each one often weighing over half the weight of the bird (the largest rocks found weighed 28 gm.; a male wheatear weighs about 38 gm.). are used in building a foundation for the nest usually placed in holes or cracks in caves or on cliffs. This habit has probably taken on the function of an advertising display and may be continued even at inappropriate nest‐sites as a compulsive pattern of behaviour. Even thousands of rocks accumulate over the years under some nest‐sites. Incubation was approximately 16–17 days, and only the female incubated. Attentive and inattentive periods of incubation were recorded. Fledging took 14–15 days.Most feeding by Black Wheatears was on the ground, but fairly frequent flights, sometimes rather long, were taken to catch insects in the air. Some feeding was done on bushes and in caves or dark rocky recesses. Sardinian and Dartford Warblers and Chiffchaffs were seen a number of times to follow and feed near wheatears for no apparent reason. Large body‐size, relatively long beak, and bristly modifications of feathers in the beak region aid the Black Wheatear in successfully and safely handling large or poisonous insects and lizards and obtaining food in thorny bushes.Analyses of droppings and pellets showed that the most important food was beetles, of which eight families were identified, especially Chrysomelidae (Chrysomela affinis, the most common species), Scarabeidae, and Tenebrionidae. Ants of several species were also a frequent food in all months. Honeybees were an important item. Millepedes were occasionally taken, andAsparagus acutifoliusfruits. Masses of insect exoskeletal parts are disgorged as well‐formed pellets, presumably formed in the strong muscular gizzard. Such pellets are not strictly comparable to raptor pellets containing large indigestible parts.