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How does the pituitary gland influence bird migration?

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A herd of wildebeest, including calves, moves across a dusty savanna in Africa with scattered trees visible in the background. — Migration A herd of common wildebeest (*Connochaetes taurinus*) migrating across a dusty savanna in Africa. The animal is a keystone species (i.e., a species with a disproportionately large effect on its biological community) in plains and acacia savanna ecosystems from southeastern Africa to central Kenya.

The pituitary gland plays a critical role in animal migration by acting as a primary regulator of the endocrine system in response to environmental cues, particularly changes in day length, a phenomenon known as photoperiodism.12

As day length shifts, the pituitary gland secretes specific hormones that trigger essential physiological preparations for migration. A primary function of these hormones is to alter metabolic processes, most notably by stimulating the accumulation of fat in the bird's body tissues. This stored fat serves as the vital energy reserve required for long-distance travel.1

While the pituitary gland is central to these internal preparations, it functions in tandem with external factors. Decreasing daylight in autumn serves as a signal for the gland to initiate these changes, while additional environmental stressors—such as sudden cold weather or the depletion of food sources—can further influence the timing of a bird's departure.1