TEMPORAL VARIATION IN FOOD AVAILABILITY AND DIET OF BLACKCAPS IN OLIVE ORCHARDS

We examined temporal variation in the diet of Blackcaps (Sylvia atrica pilla) in relation to food availability in four olive orchards in sout hern Spain. Four components of the diet were considered: olive fruits, non-olive fruits, animal matter, and non-fruit plant matter. The patt ern of temporal variation in diet among olive orchards. The temporal p attern of olive availability, which differed among olive orchards as a consequence of different crops, ripening phenologies, and harvesting processes, was the main factor determining temporal variation in diet. This emphasizes the strong dependence of Blackcaps on olive fruits in this habitat. Arthropods and non-fruit plant material (the latter inc luding leaves, flowers, and seeds of weed species) were also frequentl y included in the diet. Other fruits were eaten infrequently. However, the number of fruit species per diet sample increased wherever other fruits were available (e.g., near hedges), suggesting that such sites contribute to diet diversification.