摘要 : Abstract The onset of spring migratory behavior in birds is thought to be controlled by a rigid endogenous schedule as a result of selection to time migration with environmental conditions on breeding grounds. Recent field studies... 展开 Abstract The onset of spring migratory behavior in birds is thought to be controlled by a rigid endogenous schedule as a result of selection to time migration with environmental conditions on breeding grounds. Recent field studies, however, have revealed flexibility in spring departure schedules and suggest a role for environmental factors such as weather and food availability. Here, we investigated the role of food in modifying endogenous spring migratory schedules in a captive population of Wood Thrush (Hylocichla mustelina) by quantifying nocturnal migratory restlessness (Zugunruhe) under two food treatments: control versus reduced food availability. Contrary to predictions, food reduction did not affect the onset of Zugunruhe; instead, we observed high variability in timing of Zugunruhe. However, we did find evidence that migratory fattening tended to advance in the food reduction group compared to the control group. Birds with reduced food availability maintained lower fuel loads and decreased Zugunruhe. Moreover, fuel load predicted the magnitude of Zugunruhe. These results suggest that food availability modulates the intensity of Zugunruhe in captive birds, which we interpret to indicate a decreased migratory disposition, and supports recent field studies that have demonstrated delayed spring migration departure in physically compromised birds. Our results highlight the challenging trade-off faced by migratory birds during transition periods, in this case when to depart the wintering grounds to maximize migration survival and optimize arrival timing on breeding grounds.Significance Statement Long-distant migratory songbirds travel thousands of kilometers between breeding and wintering grounds each year. To correctly time spring migration relative to anticipated conditions on the breeding grounds, it has been thought that long-distant migrants rely on a rigid spring migration timing program. This view contrasts with recent field studies of seasonal interactions which have found an important role of local environment on the wintering grounds in the timing of spring migration. In the present study, we show that experimental reduction of food during the preparation for spring migration reduced the magnitude of nocturnal migratory activity and tended to advance migratory fattening in a captive obligate long-distance migratory bird. These results suggest local environmental condition on the wintering grounds can modulate the internal migration timing program of long-distant migrants and demonstrates how periods of the annual cycle are inextricably mixed. 收起