CORRELATES OF CLUTCH DESERTION BY FEMALE COLLARED FLYCATCHERS FICEDULA-ALBICOLLIS

While clutch abandonment in birds is typically thought to be a result of the effects of poor weather, few studies have analyzed the characte ristics of abandoning females. Female Collared Flycatchers typically a bandon their clutches at low rates (average 8% over 4 years) and most do not attempt to re-nest in the same breeding season. Here we analyze clutch desertion data from five breeding seasons, including one seaso n with particularly high desertion rates (23%). In most years, clutch desertion was associated with late nesting and (independent of date) w ith small clutch size. In addition, subsequent return rates were signi ficantly lower for birds that deserted their clutches. During a partic ularly poor weather season, females that deserted their clutches were in poor body condition, relative to females that hatched young. We sug gest that the decision to desert the clutch is typically made by low-q uality parents with low energy reserves and poor prospects for offspri ng production.