Condition-dependent clutch desertion in Great Tit (Parus major) females subjected to human disturbance

Abstract

Nest desertion behaviour in relation to body condition and timing of breeding was studied in Great Tit (Parus major) females during two breeding seasons. Desertion, most likely unintentionally provoked by catching females during the incubation period, occurred at a very high rate with 41.2 and 25.6% of deserted first clutches in the two study years. The association between desertion probability, body condition (index calculated as residuals from the regression of body mass on tarsus length) and timing of breeding differed between the seasons with the highest probability of desertion among females in low condition laying early in the season in one year and females in low condition laying late in the season in the other year. Desertion probability was best predicted by body condition with females in low condition deserting at much higher rate than females in good condition. These results suggest that nest desertion by females subjected to disturbance during the early stage of the nesting cycle may be associated with the level of their body reserves, and that patterns of desertion in relation to body condition and timing of breeding may differ between years.