Pestering Grebe

Two Western Grebes, both seemingly adult and able-bodied, played a curious game in the North Basin.  One bird acted like a hungry baby, its bill wide open, neck outstretched, begging the other bird to feed it.  The other complied.  It dove underwater and, some seconds later, usually came up with a morsel that it transferred to the pretend baby’s beak.  The baby gulped down the offering and relentlessly resumed begging.  Wash, rinse, repeat.

What was going on?  This doesn’t seem to have anything to do with courtship.  These birds start courtship at the beginning of the summer migration to their breeding grounds.  The ritual consists of joint high-speed racing across the water, called “rushing.”  This is not the breeding season, and what the birds were doing didn’t resemble a mating behavior so much as a parent/child relation.  Yet the begging bird appeared fully grown; it was the same size as the other, and no reason appeared why it couldn’t do its own diving for dinner.  The pleading bird appeared quite strong physically.  It was able to power-paddle across the water toward the feeder bird by kicking both legs forcefully, sending up splashes behind it.

This episode reminded me of the begging gull that I saw a few weeks ago.  Both these birds were fully fledged and appeared able-bodied but persistently acted like babies, begging to be fed.  In the gull incident, the act fell flat.  But the other grebe, here, worked hard to comply.  Why?  I find nothing in my usual bird sources to explain this.

It’s another case of MATWOB.  Mysterious Are The Ways of Birds.

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