Original Article

Journal of Ornithology

, Volume 149, Issue 4, pp 521-527

First online:

Offspring sex ratio in the sequentially polygamous Penduline Tit Remiz pendulinus

  • René E. van DijkAffiliated withDepartment of Biology and Biochemistry, University of BathAnimal Ecology Group, Centre for Ecological and Evolutionary Studies, University of Groningen Email author 
  • , Jan KomdeurAffiliated withAnimal Ecology Group, Centre for Ecological and Evolutionary Studies, University of Groningen
  • , Marco van der VeldeAffiliated withAnimal Ecology Group, Centre for Ecological and Evolutionary Studies, University of Groningen
  • , István SzentirmaiAffiliated withDepartment of Ethology, Eötvös Loránd UniversityŐrsèg National Park
  • , Xutong YangAffiliated withDepartment of Biology and Biochemistry, University of Bath
  • , Richard Ffrench-ConstantAffiliated withDepartment of Biology and Biochemistry, University of BathCentre for Ecology and Conservation, University of Exeter
  • , Tamás SzékelyAffiliated withDepartment of Biology and Biochemistry, University of Bath

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Abstract

Despite the growing literature on facultative sex-ratio adjustment in chromosomal sex-determining vertebrate taxa (birds, mammals), the consistency of results is often low between studies and species. Here, we investigate the primary and secondary offspring sex ratio of a small passerine bird, the Eurasian Penduline Tit (Remiz pendulinus) in three consecutive years. This species has a uniquely diverse breeding system, in which the male (and/or the female) abandons the nest during egg-laying, and starts a new breeding attempt. This allowed us to test (1) whether patterns of parental care, i.e., male-only care, female-only care or biparental desertion, influence offspring sex ratio, and (2) whether the offspring sex ratio is repeatable between successive clutches of males and females. Using molecular markers to sex 497 offspring in 176 broods, we show that (1) offspring sex ratio does not depend on which parent provides care, and (2) the offspring sex ratio is not repeatable between clutches of a given individual. The overall primary and secondary offspring sex ratio at a population level is not different from parity (54 ± 6% males, and 50 ± 3% (mean ± SE), respectively). We suggest that ecological and phenotypic factors, rather than individual traits of parents, may influence offspring’s sex, and conclude that there is currently no evidence for a facultative adjustment of offspring sex ratio in the Penduline Tit.

Keywords

Parental care Breeding system Remiz pendulinus Repeatability Sex allocation