What typically triggers migration for waterfowl?

Photoperiods, or the length of daylight, are a primary trigger for migration in waterfowl. As the days grow shorter in the fall, these changes in light exposure influence hormonal changes in birds, signaling to them that it is time to migrate to warmer regions where they can find suitable conditions for winter survival.

This response to photoperiod is a well-documented biological instinct in many bird species, including waterfowl, and is crucial for synchronizing migration with seasonal resources. While temperature changes, food shortages, and predator activity can impact the behavior and survival of waterfowl, they do not fundamentally initiate the migratory process as consistently as changes in daylight exposure do. Photoperiod is the most reliable indicator of seasonal change, driving the migratory patterns of various bird species.