Prebreeding survival of Roseate Terns Sterna dougallii varies with sex, hatching order and hatching date

Ibis
Ian Nisbet; David Monticelli; Jeffrey Spendelow; Patricia Szczys
By: , and 

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Abstract

Unequal sex ratios can reduce the productivity of animal populations and are especially prevalent among endangered species. A cohort of 333 Roseate Tern Sterna dougallii chicks at a site where the adult sex ratio was skewed towards females was sexed at hatching and followed through fledging and return to the breeding area, and subsequently during adulthood. The entire regional metapopulation was sampled for returning birds. Prebreeding survival (from fledging to age 3 years) was lower in males than in females, but only among B-chicks (second in hatching order). Prebreeding survival also declined with hatching date. The proportion of females in this cohort increased from 54.6% at hatching to 56.2% at fledging and to an estimated 58.0% among survivors at age 3 years. This was more than sufficient to explain the degree of skew in the sex ratio of the adult population, but changes in this degree of skew during the study period make it difficult to identify the influence of a single cohort of recruits. Many studies of prebreeding survival in other bird species have identified effects of sex, hatching order or hatching date, but no previous study has tested for effects of all three factors simultaneously.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Prebreeding survival of Roseate Terns Sterna dougallii varies with sex, hatching order and hatching date
Series title Ibis
DOI 10.1111/ibi.12359
Volume 158
Issue 2
Year Published 2016
Language English
Publisher Academic Press
Publisher location London
Contributing office(s) Patuxent Wildlife Research Center
Description 8 p.
First page 327
Last page 334
Online Only (Y/N) N
Additional Online Files (Y/N) N