Abstrakt
We measured food provisioning to broods of Common Kingfishers Alcedo atthis. We collected regurgitated undigested fish remains from artificial nests.
Using artificial nests ensured that fish remains originated from the current nesting period and were not a result of multiple use of a nest within one breeding season or between seasons. In total, 4722 specimens of 24 fish species were identified in six nests; the remains were used to estimate the mass of individual fish prey.
Chicks were fed with fish weighing between 0.01 and 16.2 g (average: 3.0 g, median: 2.6 g). Provisioning rate significantly increased with increasing brood size from 1498 g (505 fishes for four nestlings) to 2968 g (894 fishes for eight nestlings).
During the fledging period each chick consumed on average 334 g of fish, which resulted in an estimated daily food intake of 37% of the chick's body mass (average over the entire nestling period). The average daily energy intake was 73.5 kJ per chick, which was lower than expected for birds of equivalent size.
It seems that the relatively low energy requirement of chicks, in conjunction with selecting for large and energy-rich prey, are the key factors enabling Common Kingfishers to have large and multiple broods during one breeding season. In the temperate zone of continental Europe, this reproductive strategy enables the species to compensate for the mortality caused by periodically severe winters.