Barrett Robert T, Erikstad Kjell E, Sandvik Hanno, Myksvoll Mari, Jenni-Eiermann Susi, Kristensen Ditte L, Moum Truls, Reiertsen Tone K, Vikebø Frode
Department of Natural Sciences, Tromsø University Museum PO Box 6050 Langnes, Tromsø, NO-9037, Norway.
Norwegian Institute for Nature Research, FRAM - High North Research Centre for Climate and the Environment Tromsø, NO-9296, Norway ; Centre for Biodiversity Dynamics, Department of Biology, Norwegian University of Science and Technology Trondheim, NO-7049, Norway.
Ecol Evol. 2015 Mar;5(6):1306-17. doi: 10.1002/ece3.1438. Epub 2015 Feb 26.
In many seabird studies, single annual proxies of prey abundance have been used to explain variability in breeding performance, but much more important is probably the timing of prey availability relative to the breeding season when energy demand is at a maximum. Until now, intraseasonal variation in prey availability has been difficult to quantify in seabirds. Using a state-of-the-art ocean drift model of larval cod Gadus morhua, an important constituent of the diet of common guillemots Uria aalge in the southwestern Barents Sea, we were able to show clear, short-term correlations between food availability and measurements of the stress hormone corticosterone (CORT) in parental guillemots over a 3-year period (2009-2011). The model allowed the extraction of abundance and size of cod larvae with very high spatial (4 km) and temporal resolutions (1 day) and showed that cod larvae from adjacent northern spawning grounds in Norway were always available near the guillemot breeding colony while those from more distant southerly spawning grounds were less frequent, but larger. The latter arrived in waves whose magnitude and timing, and thus overlap with the guillemot breeding season, varied between years. CORT levels in adult guillemots were lower in birds caught after a week with high frequencies of southern cod larvae. This pattern was restricted to the two years (2009 and 2010) in which southern larvae arrived before the end of the guillemot breeding season. Any such pattern was masked in 2011 by already exceptionally high numbers of cod larvae in the region throughout chick-rearing period. The findings suggest that CORT levels in breeding birds increase when the arrival of southern sizable larvae does not match the period of peak energy requirements during breeding.
在许多海鸟研究中，每年单一的猎物丰度指标被用来解释繁殖性能的变化，但相对于繁殖季节（此时能量需求最大）而言，猎物可获得的时间可能更为重要。到目前为止，海鸟猎物可获得性的季节内变化一直难以量化。利用一种先进的海洋漂移模型来研究幼体鳕鱼（Gadus morhua），它是巴伦支海西南部普通海鸠（Uria aalge）饮食的重要组成部分，我们能够在3年期间（2009 - 2011年）显示出食物可获得性与亲代海鸠体内应激激素皮质酮（CORT）测量值之间清晰的短期相关性。该模型能够以非常高的空间分辨率（4千米）和时间分辨率（1天）提取鳕鱼幼体的丰度和大小，并表明来自挪威北部相邻产卵场的鳕鱼幼体在海鸠繁殖地附近总是可获得的，而来自更遥远南部产卵场的幼体出现频率较低，但个体较大。后者成波状到达，其规模和时间，以及与海鸠繁殖季节的重叠情况，每年都有所不同。在捕获前一周内南部鳕鱼幼体出现频率较高的成年海鸠中，其CORT水平较低。这种模式仅限于南部幼体在海鸠繁殖季节结束前到达的两年（2009年和2010年）。在2011年，整个育雏期该区域鳕鱼幼体数量本就异常高，掩盖了任何此类模式。研究结果表明，当南部较大幼体的到达时间与繁殖期间能量需求高峰期不匹配时，繁殖期鸟类的CORT水平会升高。
