Listen: Greater Rhea Nests Are Filled With Dozens of Whistling Eggs

Males of this huge South American species mate with several partners, resulting in exceptionally large—and musical—clutches.

This audio story is brought to you by BirdNote, a partner of The National Audubon Society. BirdNote episodes air daily on public radio stations nationwide.

This is BirdNote.

A typical bird nest will have maybe four to six eggs neatly arranged for a parent to hunker down on.

Now, meet the Greater Rhea, South America’s largest bird. Rheas are four- to five-foot-tall flightless birds that look a good deal like Ostriches. You can find between 50 and 80 eggs in one Rhea nest! But they’re not all from the same set of parents.

Male Rheas mate with several females and then build a single nest on the ground to hold all the eggs from each of them.

Female Rheas wander around during the breeding season and mate with different males, laying eggs in each of their partner’s nests.

Males usually stay put after breeding and attend the nest. But a male Rhea might recruit a lower-ranking male to look after his first nest while he goes off to start another nest, now mating with a second set of females.

As the Rhea eggs are about to hatch, the chicks — while still inside the egg — begin to make a curious whistle. Imagine fifty or more all whistling at once:

Sometimes young chicks like to nestle in the feathers of the male’s back — good thing he has such a nice broad back for all those chicks!

For BirdNote, I’m Ashley Ahearn.


Written by Bob Sundstrom

Producer: John Kessler

Executive Producer: Sallie Bodie

Editor: Ashley Ahearn

Associate Producer: Ellen Blackstone

Assistant Producer: Mark Bramhill

Bird sounds provided by Recorded by Rosendo Fraga.

BirdNote’s theme was composed and played by Nancy Rumbel and John Kessler.

© 2020 BirdNote   January 2020

ID#  RHEA-01-2020-01-30    RHEA-01    Narrator: Ashley Ahearn