Nocturnal foraging lifts time-constraints in winter for migratory geese but hardly speeds up fueling

Climate warming advances the optimal timing of breeding for many animals. For migrants to start breeding earlier, a concurrent advancement of migration is required, including pre-migratory fueling of energy reserves. We investigate whether barnacle geese are time-constrained during pre-migratory fueling and whether there is potential to advance or shorten the fueling period to allow an earlier migratory departure. We equipped barnacle geese with GPS-trackers and accelerometers to remotely record birds’ behavior, from which we calculated time budgets. We examined how time spent foraging was affected by the available time (during daylight and moonlit nights) and thermoregulation costs. We used an energetic model to assess onset and rates of fueling, and whether geese can further advance fueling by extending foraging time. We show that during winter, when facing higher thermoregulation costs, geese consistently foraged at night, especially during moonlit nights, in order to balance their e...气候变暖推动了诸多动物最佳繁殖时机的提前。对于迁徙物种而言，若要实现繁殖期提前，则必须同步推进迁徙进程，其中涵盖迁徙前的能量储备积累环节。本研究旨在探究藤壶鹅（barnacle geese）在迁徙前储能阶段是否受时间约束，以及是否存在通过提前或缩短储能周期以实现更早迁徙启程的可能性。我们为藤壶鹅佩戴GPS追踪器（GPS-trackers）与加速度计（accelerometers）以远程记录其行为活动，并据此计算其时间预算。我们分析了觅食时长受可利用时间（包括日间与月夜时段）以及体温调节成本的影响情况。我们借助能量模型评估了储能的起始时间与速率，以及藤壶鹅能否通过延长觅食时长进一步提前储能进程。研究结果表明，在冬季体温调节成本升高的情况下，藤壶鹅会持续在夜间觅食，尤其是在月夜时段，以维持其能量……