Experimental ghrelin administration affects migratory behaviour in a songbird

Area of Science:

• Ornithology
• Neuroendocrinology
• Behavioral Ecology

Background:

• Bird migration involves significant physiological and behavioral changes.
• Stopover sites are crucial for refueling during migration.
• Hormones, including ghrelin, signal fuel availability to the brain, influencing decisions.

Purpose of the Study:

• To investigate the role of ghrelin in controlling migratory behavior in wild passerines.
• To determine if ghrelin influences stopover departure decisions in migratory birds.

Main Methods:

• Studied 53 yellow-rumped warblers (Setophaga coronata coronata) during spring migration stopover.
• Manipulated blood ghrelin concentrations via injections.
• Used automatic radio-tracking to monitor migratory behavior post-release.

Main Results:

• Acylated and unacylated ghrelin injections rapidly induced departure from the release site.
• Ghrelin's effect on departure decisions was observed within 8 hours.
• Overall migration rate was not affected by ghrelin manipulation.

Conclusions:

• Ghrelin plays a central role in modulating migratory stopover departure decisions in birds.
• This study highlights the gut-brain axis in regulating migratory behavior through metabolic hormones.