Diet of the Black-eared Wheatear Oenanthe hispanica in relation to food availability in two arid shrubsteppes

Hòdar J. A.



Abstract:

The diet of Black-eared Wheatear Oenanthe hispanica was studied by faecal analysis in two arid shrubsteppe zones of southeast Spain. A total of 197 faeces collected in spring and summer contained recognizable remains of 826 prey. Formicidae, Coleoptera and Orthoptera were the main prey taxa in the diet, both in number of prey items as well as in the amount of biomass provided. Diet composition showed marked variations throughout the study period; differences between zones were also found. Prey size was smallest in mid-summer, when the main prey type was predominantly worker ants, and largest in spring and late summer. Prey availability, measured using pitfall traps, was related to diet. Only Orthoptera and Heteroptera were positively selected over the entire study period. Ants, due to their great abundance, appeared to be consumed below availability, despite their high frequency of consumption. The vegetal fraction in the diet was small, consisting mainly of Caper (Capparis spinosa) fruit. The Black-eared Wheatear appears to behave as a generalist feeder, with a diet based on the abundant ants and supplemented with other more profitable groups when found.