
Maternal clutch reduction in the pied flycatcher Ficedula hypoleuca : an undescribed clutch size adjustment mechanism
Author(s) -
Lobato Elisa,
Moreno Juan,
Merino Santiago,
J. Sanz Juan,
Arriero Elena,
Morales Judith,
Tomás Gustavo,
Martínezde la Puente Josué
Publication year - 2006
Publication title -
journal of avian biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.022
H-Index - 76
eISSN - 1600-048X
pISSN - 0908-8857
DOI - 10.1111/j.2006.0908-8857.03776.x
Subject(s) - ficedula , biology , avian clutch size , hatching , brood , reproduction , incubation , clutch , nest (protein structural motif) , zoology , population , ecology , demography , biochemistry , physics , sociology , thermodynamics
During eight years of study of a population of pied flycatchers Ficedula hypoleuca breeding in central Spain, we observed throughout incubation 22 cases of intact eggs being placed on the nest rim and clearly outside of the nest bowl and remaining there, with consequent embryo mortality. We assume that the removal of eggs had been performed by the incubating female. There is no evidence that pied flycatcher parents can detect embryo mortality and eject unhatchable eggs. Maternal egg ejection constitutes a direct mechanism of clutch size adjustment during incubation and before hatching of any young of the brood. This adjustment of clutch size happened when the mean and minimum temperature of the day before ejection were especially low. Also, clutch‐reducing females were significantly more prone to show moult‐breeding overlap than other females, suggesting a lower disposition to invest in reproduction. Clutch‐reducing females were also frequently older than four years and had indications of a lower immunocompetence than females not ejecting eggs. Our results support the hypothesis that adverse conditions can elicit parental family size adjustment at every stage of reproduction without the need to depend on mechanisms of sibling competition.