Egg characteristics of female common terns are repeatable, and vary with maternal age and laying order

Avian eggs exhibit striking variability in size, shape, colour, and maculation, not only among, but also within species. Technical and analytical advances in image analysis offer the opportunity to understand the factors underpinning this variability, especially when individual-based longitudinal data are available. Making use of such data, collected over four years, we investigated sources of variation in eight egg characteristics capturing the colour, spottiness, shape, and size of 1589 eggs from 687 clutches produced by 330 female common terns (Sterna hirundo) of known age. We found a high repeatability of the eight egg traits, both within clutches (range 0.48 – 0.77), and among clutches of the same female laid in different years (range 0.48 – 0.73). We also observed a within-female increase in egg size and spottiness with age, and evidence for selective disappearance of females producing spottier eggs, suggesting that egg maculation could reveal female quality. We also found that th..., , READ ME FOR Dryad_data_rep_eggs.csv

Data used for analyses presented in:
Egg Characteristics of Female Common Terns Are Repeatable, and Vary With Maternal Age and Laying Order
by Bichet, C., Moiron, M., Kürten N., Vedder O., & Bouwhuis S.
published in Ecology and Evolution

for information regarding the data or analyses, please contact [[e-mail]](mailto:[e-mail])
and [[e-mail]](mailto:[e-mail])

these data are part of those collected in an ongoing individual-based longitudinal population study
additional data are likely to be available, and we are often very happy to collaborate
provided that none of our own staff or students is working on a conflicting project

* Female_ID: identity of the females
* age: age in years
* year: breeding season
* nest_id: Identity of the nest
* CSLO: CS for clutch size and LO for a laying order
* The next columns are the egg parameters related to maculation, colouration,...,