Consequences of experimental clutch enlargement in a High Arctic single-egg layer, the Little Auk (Alle alle)

Canadian Journal of Zoology, e-First Articles.

Initial reproductive investments in birds are energy-demanding. Amount of energy allocated to egg production and incubation may have an important role in determining parental fitness and evolution of clutch size. Here, we investigated whether the Little Auk (Alle alle (L., 1758)), a small alcid with one-egg clutch but two brood patches (probably remnant of the original two-egg clutch), is capable of incubating two eggs and rearing two chicks. We performed an experiment with removing the egg from 20 nests and transferring it to 20 experimental nests (EN). In 25% of EN, both eggs failed to hatch; in 75% of EN, only one egg hatched successfully. Hatching success in EN was 2.5 times lower than in control nests (CN). In EN, chicks hatched only from eggs warmed during >90% of inspections. Owing to the prolonged incubation, the chicks in EN hatched 2 days later than in CN. However, due to the shorter period spent in the nest in EN, fledging dates in both types of nests were similar. The similar body mass and survival of chicks from EN and CN suggest that these traits were influenced mainly by the rearing conditions. Our study emphasize the importance of the incubation phase as a constraint on clutch size.

Source: Canadian Journal of Zoology - May 26, 2014 Category: Zoology Tags: article Source Type: research