Sex-biased hatching sequences in the cooperatively breeding Noisy Miner

Kathryn E. Arnold*, Simon C. Griffith, Anne W. Goldizen

*Corresponding author for this work

Research output: Contribution to journalArticle

30 Citations (Scopus)


The Noisy Miner Manorina melanocephala (Meliphagidae) is a cooperatively breeding bird species in which sons often remain on their natal home ranges and help one or both of their parents. In a population of Noisy Miners in SE Queensland, Australia, a molecular technique was used to explore adult and offspring sex ratios, and also hatching sequences. Among the adult population, there were 2.31 males for every female, and roughly 99% of helping was performed by males. At hatching and fledging, the population sex ratio was even, with exactly 57 males and 57 females. However, in 17 out of 18 broods the first egg to hatch was male. First-hatched males were significantly larger and heavier than their sisters just prior to fledging. Through their helping behaviour, large healthy sons could clearly enhance the future reproductive success of parents, and benefit the entire group. Sex-biased hatching sequences could potentially provide cooperatively breeding birds with a subtle and precise way of varying investment in the helping sex.

Original languageEnglish
Pages (from-to)219-223
Number of pages5
JournalJournal of Avian Biology
Issue number3
Publication statusPublished - 2001
Externally publishedYes

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