在北太平洋地区生活着一种黑色海鸟——小海雀，其雄鸟头上长有羽冠。一项新研究表明，这种羽冠的尺寸是雄小海雀生存能力大小的“特征标志”，羽冠越大的雄小海雀越容易找到“对象”。
美国阿拉斯加大学费尔班克斯分校的赫克·道格拉斯等人在《比较生理学Ｂ》（Journal of Comparative Physiology B）上发表论文说，雌小海雀喜欢羽冠大的雄小海雀，但科学家一直不清楚其中的原因。他们于是在2002年从美国阿留申群岛捕捉了一些小海雀进行研究，结果发现，羽冠越大的雄小海雀，其体内的压力激素——皮质醇的水平越低。
道格拉斯说，雄性体内的压力激素越少，越容易适应外部环境，羽冠大的雄小海雀在寻找食物、与其他雄鸟争夺筑巢地点以及帮助孵化和培育后代方面都占有优势。
研究人员因此推断，羽冠是雄小海雀用来赢取雌性“芳心”的“外在特征标志”，而不只是好看的“装饰物”。（生物谷Bioon.com）
生物谷推荐原始出处：
Journal of Comparative Physiology B，doi:10.1007/s00360-008-0312-6，Hector D. Douglas III，Alexander S. Kitaysky
Size of ornament is negatively correlated with baseline corticosterone in males of a socially monogamous colonial seabird
Hector D. Douglas III1, 2 , Alexander S. Kitaysky3, Evgenia V. Kitaiskaia3, Aidan Maccormick4 and Anke Kelly5, 6
(1)Institute of Marine Science, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
(2)Biology Department, Kuskokwim Campus, CRCD, University of Alaska Fairbanks, Bethel, AK 99559, USA
(3)Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
(4)Division of Environmental and Evolutionary Biology, Institute of Biomedical and Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow, G12 8QQ, UK
(5)Department of Animal Physiology, University of Bayreuth, 95440 Bayreuth, Germany
(6)Biology Department, Brandeis University, Waltham, MA 02454, USA
The Goymann–Wingfield model predicts that glucocorticoid levels in social animals reflect the costs of acquiring and maintaining social status. The crested auklet is one of the few avian colonial species where a mutual ornament in males and females is used in both sexual and aggressive displays. Previous studies of the crested auklet support the notion that the crest ornament is a badge of status in this species. Here, we examined the relationship between the crest ornament size and the adrenocortical function in breeding crested auklets. Crest length was negatively correlated with corticosterone at baseline in males, but not in females. Baseline corticosterone in females (but not in males) was negatively correlated with body condition index. Although male and female crested auklets are monomorphic in their ornamental traits, our results suggest that the socially mediated physiological costs associated with status signaling may differ between the sexes.
