Multi-Year Seasonal Sex-Allocation Patterns in Red-Winged Blackbirds (Agelaius Phoeniceus)
A previous study reported that climate-mediated increases in the length of the breeding season produced increasingly female-biased fledging sex ratios in Red-winged Blackbirds (Agelaius phoeniceus). Using those same data plus one additional year (11 years in total), I found that this phenomenon was...
Published in: | The Auk |
---|---|
Main Author: | |
Format: | Text |
Language: | English |
Published: |
American Ornithological Society
2009
|
Subjects: | |
Online Access: | https://doi.org/10.1525/auk.2009.08024 |
id |
ftbioone:10.1525/auk.2009.08024 |
---|---|
record_format |
openpolar |
spelling |
ftbioone:10.1525/auk.2009.08024 2024-05-12T08:08:08+00:00 Multi-Year Seasonal Sex-Allocation Patterns in Red-Winged Blackbirds (Agelaius Phoeniceus) Patrick J. Weatherhead Patrick J. Weatherhead world 2009-01-01 text/HTML https://doi.org/10.1525/auk.2009.08024 en eng American Ornithological Society doi:10.1525/auk.2009.08024 All rights reserved. https://doi.org/10.1525/auk.2009.08024 Text 2009 ftbioone https://doi.org/10.1525/auk.2009.08024 2024-04-16T02:13:14Z A previous study reported that climate-mediated increases in the length of the breeding season produced increasingly female-biased fledging sex ratios in Red-winged Blackbirds (Agelaius phoeniceus). Using those same data plus one additional year (11 years in total), I found that this phenomenon was not a result of greater production of females early and late in the season, contrary to what had been proposed. Instead, seasonal sex-allocation patterns interacted with season length. Early and midseason sex ratios became more female-biased as breeding seasons became longer, whereas late-season sex ratios tended to vary in the opposite manner, albeit weakly. Thus, the discrepancy between sex ratios late in the season and those earlier (early plus midseason) was a strong function of season length. Because fledging sex ratios did not vary with nestling mortality, these patterns appear to be a consequence of nonrandom sex-allocation rather than sex-biased survival. It is unclear whether these sex-allocation patterns are adaptive. Because the climatic factor (the North Atlantic Oscillation) associated with longer breeding seasons is also associated with higher winter mortality, however, it is possible that female Red-winged Blackbirds change how they allocate sex in response to changes in the breeding sex ratio. If climate change continues to alter these patterns, documenting how individuals and populations respond will be informative, from both basic and applied perspectives. Text North Atlantic North Atlantic oscillation BioOne Online Journals The Auk 126 1 181 185 |
institution |
Open Polar |
collection |
BioOne Online Journals |
op_collection_id |
ftbioone |
language |
English |
description |
A previous study reported that climate-mediated increases in the length of the breeding season produced increasingly female-biased fledging sex ratios in Red-winged Blackbirds (Agelaius phoeniceus). Using those same data plus one additional year (11 years in total), I found that this phenomenon was not a result of greater production of females early and late in the season, contrary to what had been proposed. Instead, seasonal sex-allocation patterns interacted with season length. Early and midseason sex ratios became more female-biased as breeding seasons became longer, whereas late-season sex ratios tended to vary in the opposite manner, albeit weakly. Thus, the discrepancy between sex ratios late in the season and those earlier (early plus midseason) was a strong function of season length. Because fledging sex ratios did not vary with nestling mortality, these patterns appear to be a consequence of nonrandom sex-allocation rather than sex-biased survival. It is unclear whether these sex-allocation patterns are adaptive. Because the climatic factor (the North Atlantic Oscillation) associated with longer breeding seasons is also associated with higher winter mortality, however, it is possible that female Red-winged Blackbirds change how they allocate sex in response to changes in the breeding sex ratio. If climate change continues to alter these patterns, documenting how individuals and populations respond will be informative, from both basic and applied perspectives. |
author2 |
Patrick J. Weatherhead |
format |
Text |
author |
Patrick J. Weatherhead |
spellingShingle |
Patrick J. Weatherhead Multi-Year Seasonal Sex-Allocation Patterns in Red-Winged Blackbirds (Agelaius Phoeniceus) |
author_facet |
Patrick J. Weatherhead |
author_sort |
Patrick J. Weatherhead |
title |
Multi-Year Seasonal Sex-Allocation Patterns in Red-Winged Blackbirds (Agelaius Phoeniceus) |
title_short |
Multi-Year Seasonal Sex-Allocation Patterns in Red-Winged Blackbirds (Agelaius Phoeniceus) |
title_full |
Multi-Year Seasonal Sex-Allocation Patterns in Red-Winged Blackbirds (Agelaius Phoeniceus) |
title_fullStr |
Multi-Year Seasonal Sex-Allocation Patterns in Red-Winged Blackbirds (Agelaius Phoeniceus) |
title_full_unstemmed |
Multi-Year Seasonal Sex-Allocation Patterns in Red-Winged Blackbirds (Agelaius Phoeniceus) |
title_sort |
multi-year seasonal sex-allocation patterns in red-winged blackbirds (agelaius phoeniceus) |
publisher |
American Ornithological Society |
publishDate |
2009 |
url |
https://doi.org/10.1525/auk.2009.08024 |
op_coverage |
world |
genre |
North Atlantic North Atlantic oscillation |
genre_facet |
North Atlantic North Atlantic oscillation |
op_source |
https://doi.org/10.1525/auk.2009.08024 |
op_relation |
doi:10.1525/auk.2009.08024 |
op_rights |
All rights reserved. |
op_doi |
https://doi.org/10.1525/auk.2009.08024 |
container_title |
The Auk |
container_volume |
126 |
container_issue |
1 |
container_start_page |
181 |
op_container_end_page |
185 |
_version_ |
1798851034087424000 |