Inter-annual variation in clutch size and laying date of Rufous Bush Chats Cercotrichas galactotes inhabiting an Algerian oasis

Abstract

We studied clutch size and timing of breeding of Rufous Bush Chats Cercotrichas galactotes inhabiting Date Palm plantations in an oasis in NE Algeria with respect to interannual variation. Although oases may be assumed to provide relatively stable ecological conditions favourable for some insectivorous birds, including Rufous Bush Chats, we found relatively high year-to-year variation in the life history traits analysed. In general, clutch size was negatively related to the egg-laying date, with this relation differing between years. This suggests that clutch size was probably determined by a combination of within-year and between-year factors partly operating through the timing of reproduction. The most important of these factors were probably the amount of rainfall and year-to-year growth of palm trees.