Epaulet Brightness and Condition in Female Red-Winged Blackbirds
Epaulet Brightness and Condition in Female Red-Winged Blackbirds
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雌性红翅黑鸟的肩章亮度和状况
DOI：
10.2307/4088902
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
V. Nolan
中科院分区：
文献类型：
--
作者：
T. S. Johnsen;James D. Hengeveld;J. Blank;K. Yasukawa;V. Nolan
雌性红翅乌鸫（Agelaius phoeniceus）的肩章颜色从棕色到亮橙色不等。我们测试的假设，条件在蜕皮时决定女性肩章亮度和女性在上级条件下产生更明亮的肩章的预测。我们比较了每个女性的肩章与一系列的彩色照片排名从1（暗棕色）到12（明亮的红橙色），并认为女性之间的亮度增加，如果他们的颜色增加了至少两个等级。更多的第一年的女性比老年女性增加亮度，更多的老年女性增加亮度后，低生殖努力比高努力后，和更多的第一年的女性增加亮度后，一年的过剩食物（出现周期性蝉，Magicicada属）。比其他年份。在每种情况下，我们都希望情况有所改善。我们估计女性的条件和回归条件指数的繁殖季节的一天。在繁殖季节，女性后来增加亮度改善条件相对于女性没有增加亮度。我们证实了先前报道的年龄和肩章亮度之间的相关性，但年龄并不能解释亮度变化与繁殖努力或蝉的出现之间的关系。我们的结论是，我们的研究结果最有可能的解释是，条件，至少部分地，确定肩章亮度在女性红翼黑鸟和上级条件反映了更明亮的肩章。我们的研究结果支持的状态信号假说和择偶假说的可变羽毛的演变的假设。对雌性红翼黑鹂进化出可变羽毛的最好解释是，亮度在雌性与雌性的攻击性遭遇中发出地位信号。11月21日收到
Epaulets of female Red-winged Blackbirds (Agelaius phoeniceus) vary in bright- ness from brown to bright red-orange. We test predictions of the hypothesis that condition at the time of molt determines female epaulet brightness and that females in superior con- dition produce brighter epaulets. We compared each female's epaulet with a series of color photographs ranked from 1 (dull brown) to 12 (bright red-orange) and considered females to have increased in brightness between years if their color increased by at least two ranks. More first-year females than older females increased in brightness, more older females in- creased in brightness after low reproductive effort than after high effort, and more first-year females increased in brightness after a year of superabundant food (an emergence of periodical cicadas, Magicicada spp.) than after other years. In each case, we expected an improvement in condition. We estimated female condition and regressed condition index on day of the breeding season. During the breeding season, females that later increased in brightness improved in condition relative to females that did not increase in brightness. We confirm a previously reported correlation between age and epaulet brightness, but age does not explain the relationship between change in brightness and either reproductive effort or the emergence of cicadas. We conclude that the most likely explanation for our results is that condition, at least in part, determines epaulet brightness in female Red-winged Blackbirds and that superior condition is reflected by brighter epaulets. Our results support assumptions of the status- signaling hypothesis and mate-choice hypotheses for the evolution of variable plumage. The best explanation for the evolution of variable plumage among female Red-winged Blackbirds is that brightness signals status in female-female aggressive encounters. Received 21 November