We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Growth rate, size, and sex ratio of last-laid, last-hatched offspring in the tree swallow Tachycineta bicolor.
- Authors
Johnson, L. Scott; Wimmers, Larry E.; Campbell, Sara; Hamilton, Lucy
- Abstract
In tree swallows Tachycineta bicolor , last-laid eggs typically hatch one to two days after the other eggs in the clutch hatch, putting last-hatched offspring at a disadvantage when competing for food delivered by parents. We studied the biology of last-laid, last-hatched tree swallow offspring over two years in a Wyoming, USA, population. Our first objective was to compare the growth of last-hatched offspring to that of their earlier-hatched nestmates. One previous study had suggested that last-hatched, competitively disadvantaged offspring grow feathers faster than senior nestmates, even at the expense of other aspects of growth. This may allow last-hatched offspring to fledge with senior nestmates and avoid abandonment by parents. A second objective was to determine the sex of nestlings from last-laid eggs. If last-laid eggs typically produce undersized, weak adults that are poor competitors for resources, and if the fitness costs of being undersized/weak are more severe for males than for females, then selection may favour having offspring from last-laid eggs to be female. In this study, last-laid eggs hatched in 63 of 66 (94%) nests and hatched last in 93% of cases. At hatching, offspring from last-laid eggs weighed, on average, 63% as much as their three heaviest nestmates (range: 26–107%). Offspring from last-laid eggs fledged from 71% of the nests that produced at least one fledgling and apparently starved to death in remaining nests. Last-hatched offspring who were presumably at a substantial competitive disadvantage (those whose mass at hatching was no more than about 75% of the mean mass of their three heaviest nestmates), gained mass more slowly than their senior nestmates but they eventually attained the same peak mass before fledging. Last-hatched offspring grew primary feathers more slowly than their senior nestmates although the difference in growth rate was slight (0.2 mm/d) and only marginally significant. As a group, offspring from...
- Subjects
TREE swallow; TACHYCINETA
- Publication
Journal of Avian Biology, 2003, Vol 34, Issue 1, p35
- ISSN
0908-8857
- Publication type
Article
- DOI
10.1034/j.1600-048X.2003.02950.x