Parental expenditure for rearing nestlings by ravensCorvus corax | Aufwand für die Jungenaufzucht beim KolkrabenCorvus corax: Einfluß von Jungenzahl und Witterung
1997
Thöni, Barbara
In spring 1995 (Feb.–May) I observed seven pairs of Raven in southern Germany on the “Schwäbischen Alb”. The aim was to record parental expenditure for rearing nestlings. Expenditure was assessed by recording the activities of the adults at their nest (mainly brooding and feeding the offspring) and was analysed with respect to the number of nestlings per brood and with respect to the weather. Pairs with more than one nestling saved effort by stopping brooding their offspring at a lower nestling age. Also brooding was less dependent on the ambient temperature for pairs with more than one nestling than for pairs with only one nestling. The feeding frequency per nestling has been lower, if there were more nestlings to feed. The total frequency of feeding increased with increasing number of nestlings per brood. The effort for the hygiene of the nest was independent upon the number of offspring per nest. Nevertheless, pairs with more than one nestling spent time for comfort behaviour. Thus, it was more effective to reare more than one nestling at a time.
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