Social environment influences termination of nomadic migration

The final stage of migration, when animals terminate migratory movements and transition to a more sedentary state, remains the least understood phase of migration. Whereas migrants that return to the same locations each year may use mechanisms associated with locating a specific destination, migrants with low site fidelity, such as nomadic migrants, may rely on local environmental cues to determine when to cease migratory movements. Using an experiment with captive birds, we tested whether the presence of a conspecific influences the termination of migration, indicated by changes in behaviour and physiology, in a nomadic migrant (the pine siskin, Spinus pinus). We paired migratory birds with a non-migratory individual or left migratory and non-migratory individuals unpaired. Migratory paired birds had a significant decline in nocturnal activity immediately after pairing and activity levels remained lower two weeks later, with significant declines in energetic reserves and flight muscle ...动物终止迁徙活动并转入更久坐状态的迁徙最终阶段，仍是目前学界认知最为匮乏的迁徙环节。每年返回同一栖息地点的迁徙物种，可借助定位特定目的地的相关机制完成迁徙；而栖地忠实性（site fidelity）较低的迁徙类群（如游牧式迁徙者），则依赖当地环境线索判断何时终止迁徙活动。本研究通过圈养鸟类实验，以游牧迁徙物种松金翅雀（Spinus pinus）为对象，探究同种个体的存在是否会对迁徙终止过程产生影响——该过程可通过行为与生理变化加以表征。实验设置两组处理：将迁徙个体与非迁徙个体配对，或使迁徙与非迁徙个体保持未配对状态。配对后的迁徙个体在配对后即刻出现夜间活动量的显著下降，且两周后活动水平仍维持低位，同时其能量储备与飞行肌肉也出现显著下降……