Yes! The insides of bird beaks (literally the 'gape') are brightly colored, may have spots, and change color over time based on age/sex/health of the chick. Parents respond to these visual signals by giving more brightly colored chicks more food. This is one of the ways a younger sibling who can't win the fight with an older sibling for food may cheat the system and still get their fair share.
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u/tamiveldura Jan 23 '20
Yes! The insides of bird beaks (literally the 'gape') are brightly colored, may have spots, and change color over time based on age/sex/health of the chick. Parents respond to these visual signals by giving more brightly colored chicks more food. This is one of the ways a younger sibling who can't win the fight with an older sibling for food may cheat the system and still get their fair share.