Eby Alyssa, Patterson Allison, Whelan Shannon, Elliott Kyle H, Gilchrist H Grant, Love Oliver P
Department of Integrative Biology, University of Windsor, 401 Sunset Avenue, Windsor, ON, N9B 3P4, Canada.
Department of Natural Resource Sciences, McGill University, 21111 Lakeshore Road, Ste Anne-de-Bellevue, Quebec, H9X 3V9, Canada.
Conserv Physiol. 2024 Sep 5;12(1):coae057. doi: 10.1093/conphys/coae057. eCollection 2024.
Declining sea ice and increased variability in sea ice dynamics are altering Arctic marine food webs. Changes in sea ice dynamics and prey availability are likely to impact pagophilic (ice-dependent and ice-associated) species, such as thick-billed murres (), through changes in foraging behaviour and foraging success. At the same time, extrinsic factors, such as chick demand, and intrinsic factors, such as sex, are also likely to influence foraging behaviour and foraging success of adult murres. Here, we use 3 years of data (2017-2019) to examine the impacts of environmental conditions (sea ice concentration and sea surface temperature), sex and chick age (as a proxy for chick demand) on foraging and diving behaviour (measured via biologgers), energy expenditure (estimated from activity budgets) and foraging success (measured via nutritional biomarkers) of thick-billed murres during the incubation and chick-rearing stages at Coats Island, Nunavut. Murres only exhibited foraging flexibility to environmental conditions during incubation, which is also the only stage when ice was present. When more ice was present, foraging effort increased, murres foraged farther and made deeper dives, where murres making deeper dives had higher foraging success (greater relative change in mass). During incubation, murre behaviour was also influenced by sex of the individual, where males made more and shorter trips and more dives. During chick-rearing, murre behaviour was influenced primarily by the sex of the individual and chick age. Males made shallower dives and fewer dive bouts per day, and more dives. Birds made longer, deeper dives as chicks aged, likely representing increased intra-specific competition for prey throughout the season. Our results suggest variation in sea ice concentration does impact foraging success of murres; however, sex-specific foraging strategies may help buffer colony breeding success from variability in sea ice concentration.
海冰减少以及海冰动态变化的加剧正在改变北极海洋食物网。海冰动态和猎物可获得性的变化可能会通过觅食行为和觅食成功率的改变，影响嗜冰（依赖冰和与冰相关）物种，如厚嘴海鸦。与此同时，外在因素，如雏鸟需求，以及内在因素，如性别，也可能影响成年海鸦的觅食行为和觅食成功率。在此，我们利用3年（2017 - 2019年）的数据，研究环境条件（海冰浓度和海面温度）、性别和雏鸟年龄（作为雏鸟需求的指标）对努纳武特地区科茨岛厚嘴海鸦在孵化和育雏阶段的觅食与潜水行为（通过生物记录器测量）、能量消耗（根据活动预算估算）以及觅食成功率（通过营养生物标志物测量）的影响。海鸦仅在孵化期间表现出对环境条件的觅食灵活性，而这也是有冰存在的唯一阶段。当有更多冰时，觅食努力增加，海鸦觅食距离更远且潜水更深，潜水更深的海鸦有更高的觅食成功率（体重相对变化更大）。在孵化期间，海鸦的行为也受个体性别的影响，雄性的行程更多、更短且潜水次数更多。在育雏期间，海鸦的行为主要受个体性别和雏鸟年龄的影响。雄性每天潜水更浅、潜水回合更少，但潜水次数更多。随着雏鸟长大，海鸟的潜水时间更长、更深，这可能代表着整个季节种内对猎物的竞争加剧。我们的研究结果表明，海冰浓度的变化确实会影响海鸦的觅食成功率；然而，特定性别的觅食策略可能有助于缓冲海冰浓度变化对群体繁殖成功率的影响。
