Storey Anne E, Ryan Morag G, Fitzsimmons Michelle G, Kouwenberg Amy-Lee, Takahashi Linda S, Robertson Gregory J, Wilhelm Sabina I, McKay Donald W, Herzberg Gene R, Mowbray Frances K, MacMillan Luke, Walsh Carolyn J
Department of Psychology, Memorial University, St. John's, Newfoundland and Labrador, Canada A1B 3×9.
Department of Biology, Memorial University, St. John's, Newfoundland and Labrador, Canada A1B 3×9.
Conserv Physiol. 2017 Sep 26;5(1):cox055. doi: 10.1093/conphys/cox055. eCollection 2017.
Seabird parents use a conservative breeding strategy that favours long-term survival over intensive parental investment, particularly under harsh conditions. Here, we examine whether variation in several physiological indicators reflects the balance between parental investment and survival in common murres () under a wide range of foraging conditions. Blood samples were taken from adults during mid-chick rearing from 2007 to 2014 and analysed for corticosterone (CORT, stress hormone), beta-hydroxybutyrate (BUTY, lipid metabolism reflecting ongoing mass loss), and haematocrit (reflecting blood oxygen capacity). These measures, plus body mass, were related to three levels of food availability (good, intermediate, and poor years) for capelin, the main forage fish for murres in this colony. Adult body mass and chick-feeding rates were higher in good years than in poor years and heavier murres were more likely to fledge a chick than lighter birds. Contrary to prediction, BUTY levels were higher in good years than in intermediate and poor years. Murres lose body mass just after their chicks hatch and these results for BUTY suggest that mass loss may be delayed in good years. CORT levels were higher in intermediate years than in good or poor years. Higher CORT levels in intermediate years may reflect the necessity of increasing foraging effort, whereas extra effort is not needed in good years and it is unlikely to increase foraging success in poor years. Haematocrit levels were higher in poor years than in good years, a difference that may reflect either their poorer condition or increased diving requirements when food is less available. Our long-term data set provided insight into how decisions about resource allocation under different foraging conditions are relating to physiological indicators, a relationship that is relevant to understanding how seabirds may respond to changes in marine ecosystems as ocean temperatures continue to rise.
海鸟父母采用一种保守的繁殖策略，这种策略更倾向于长期生存而非大量的亲代投入，尤其是在恶劣条件下。在此，我们研究了在广泛的觅食条件下，几种生理指标的变化是否反映了普通海鸦（）亲代投入与生存之间的平衡。在2007年至2014年雏鸟饲养中期采集成年海鸦的血样，分析其中的皮质酮（CORT，应激激素）、β-羟基丁酸（BUTY，反映持续体重减轻的脂质代谢指标）和血细胞比容（反映血液携氧能力）。这些指标，再加上体重，与毛鳞鱼（该海鸦栖息地的主要捕食鱼类）的三个食物可利用水平（丰年、平年和歉年）相关。丰年成年海鸦的体重和育雏率高于歉年，较重的海鸦比较轻的海鸦更有可能成功育雏。与预测相反，丰年的BUTY水平高于平年和歉年。海鸦在雏鸟孵化后体重会下降，而这些BUTY的结果表明，在丰年体重下降可能会延迟。平年的CORT水平高于丰年或歉年。平年较高的CORT水平可能反映了增加觅食努力的必要性，而丰年不需要额外努力，歉年增加觅食努力也不太可能提高觅食成功率。歉年的血细胞比容水平高于丰年，这种差异可能反映了它们较差的身体状况，或者在食物较少时潜水需求增加。我们的长期数据集深入了解了在不同觅食条件下资源分配决策与生理指标之间的关系，这种关系对于理解随着海洋温度持续上升海鸟如何应对海洋生态系统变化具有重要意义。
