FREQUENCY AND TIMING OF SUCCESSIVE BROODS IN CAPTIVE AFRICAN AND EUROPEAN STONECHATS SAXICOLA-TORQUATA-AXILLARIS AND SAXICOLA-TORQUATA-RUBICOLA

African Stonechats at the equator in Kenya breed only once per breedin g season, whereas European Stonechats breed two or three times. To lea rn whether this difference in annual brood number results mainly from the differences in environmental conditions in the field or is endogen ously determined, pairs of both subspecies were kept in controlled con ditions and their breeding behaviour was monitored. In the laboratory the difference between the subspecies found in the field was no longer observed: both the European and the African Stonechats were multi-bro oded. In both subspecies the second or third clutches were laid while the preceding brood was still being raised (''telescoping''). However, the inter-brood intervals were longer for African than for European p airs. A possible functional implication of this difference is discusse d. The finding that African Stonechats are just as capable as those of the European subspecies of producing multiple broods suggests that br ood number in the field is limited by particular environmental factors . Canditates considered include limitation of a favourable food supply to the rainy season and the timing of the latter with respect to the endogenous ''breeding window''. Field observations suggest that in cer tain exceptional conditions African Stonechats might be able to produc e two broods.