Clutch size increases with increasing nest size in birds
Published: 9 October 2014
Bird populations using nest boxes are a classic study system to test evolutionary and ecological hypothesis. An important aspect of such studies is the measurement of reproductive success of individuals. Yet the very tool that makes them attractive for population studies, that they use nest boxes, also affects how many eggs they will lay, an important aspect of reproductive success.
Bird populations using nest boxes are a classic study system to test evolutionary and ecological hypothesis. An important aspect of such studies is the measurement of reproductive success of individuals. Yet the very tool that makes them attractive for population studies, that they use nest boxes, also affects how many eggs they will lay, an important aspect of reproductive success. If indeed birds in larger nest boxes lay more eggs and different studies use different sized nest boxes then results will not be compatible. However, we know that between studies, and sometimes even within studies, nest boxes of different sizes are used.
To test if this is so, this study used three different data sets. First, experimental data from an old experiment on great tits where nest box size was manipulated. Second, data found in the literature on 21 species where clutch size and nest size was known and a thirdly, a data set on clutch and nest box size on four secondary hole nesting birds in Europe and North Africa which included 79,610 clutches spanning a combined 3481 study years across the 4 species (Møller et al 2014).
The analyses showed that across many species and populations females breeding in a larger nest boxes indeed laid more eggs. What is very interesting though is that the exact relationship differs among populations of the same species but also between different species. That suggests that there is no one simple reason for this relationship between clutch size and nest size.
This has a very important lesson for researchers that want to study reproductive success in nest box-breeding species and compare this with other studies. With choosing what nest box size to use they will affect the number of eggs laid in the first place. And another study might have used a different nest box size and thus reproductive success does no longer become directly comparable. Even if that relationship between nest box size and clutch size is established in one population this can not necessarily be applied to any other population even of the same species. This same issue might also apply to many other taxa but data are still lacking.
http://onlinelibrary.wiley.com/doi/10.1002/ece3.1189/pdf
First published: 9 October 2014