Translator Disclaimer
1 June 2009 Variation in the Relationship between Lay Date and Clutch Size in Three Cavity-Nesting Woodland Passerines
Anne E. Goodenough, Simon L. Elliot, David P. Maitland, Adam G. Hart
Author Affiliations +
Abstract

Clutch sizes of many single-brooded birds decrease as the breeding season progresses. This decrease is usually quantified using data from several years, an approach that would mask any annual variation. We used 15 years of data from 295 nestboxes occupied by Blue Tit, Great Tit and Pied Flycatcher to determine whether the strength of the relationship between lay date and clutch size is consistent, or whether it varies annually. Both lay date and year were strong predictors of clutch size for all species. However, Generalised Linear Modelling revealed an interaction between lay date and year in the prediction of clutch size, indicating that the strength of the relationship between lay date and clutch size varied between years. Multilevel modelling was used to establish proximate factors that may be responsible for annual variability. Factors affecting the relationship between lay date and clutch size were species-specific. For Blue Tits, seasonal decline in clutch size was steepest when the density of all cavity-nesting species was high (47% variance explained). For Great Tits, decline was steepest in “early” seasons, particularly when density was high (32% variance explained), and for Pied Flycatchers, decline was steepest in warmer years (33% variance explained). Thus annually variable factors appear to influence not only breeding phenology and clutch size individually, but also the relationship between these variables.

Anne E. Goodenough, Simon L. Elliot, David P. Maitland, and Adam G. Hart "Variation in the Relationship between Lay Date and Clutch Size in Three Cavity-Nesting Woodland Passerines," Acta Ornithologica 44(1), 27-36, (1 June 2009). https://doi.org/10.3161/000164509X464858
Received: 1 July 2008; Accepted: 1 January 2009; Published: 1 June 2009
JOURNAL ARTICLE
10 PAGES


Share
SHARE
KEYWORDS
annual variability
clutch size
Cyanistes caeruleus
Ficedula hypoleuca
lay date
multilevel modelling
Parus major
RIGHTS & PERMISSIONS
Get copyright permission
Back to Top