Editor's Choice: Delayed timing of breeding as a cost of reproduction
Submitted by Johan on 20 July 2015.Get the paper!
The start of breeding during a season has generally a large impact on reproductive success in passerines. Given the importance of this trait, we know astonishingly little about what factors determine the start of breeding in individual birds. In an exciting paper, Low et al. suggest that a female’s possibility to start to lay eggs early is governed by her reproductive cost during the previous season.
The authors monitored the arrival date and start of egg laying in a well-studied population of northern wheatears (Oenanthe oenanthe). They found that females that terminated breeding early due to a failed breeding attempt returned earlier during the next spring and initiated egg laying earlier than did successful breeders. Also breeders that invested a lot in a previous breeding season, by for example producing replacement clutches after initial failure, tended to arrive later than females with a normal breeding attempt during the previous year. Such carry-over effects between seasons are conceptually logical but very few studies have been able to actually show them. This very valuable paper triggers lots of questions about mechanisms – how does reproductive investment affect autumn migration, establishment on wintering grounds and return migration to produce the variation in subsequent reproduction found in this paper.
Jan-Åke Nilsson, Editor in Chief
This paper is an Open Access publication and can be downloaded for free: http://onlinelibrary.wiley.com/doi/10.1111/jav.00623/full