Friday, January 30, 2015

What on earth is a Rhea?

If you enter the Environmental Education Center (also called our Visitor’s Center) at World Bird Sanctuary, one of the many displays you’ll see contains the eggs of various birds.  It shows you how similar – and different – eggs can be.

Note the Hummingbird egg (2nd shelf from bottom, 3rd egg from left) (photo: Gay Schroer)

The smallest egg in the display is that of a hummingbird, while an entire shelf is dedicated to the three largest eggs – those of the ostrich, emu, and rhea.  The ostrich is the largest bird, found loping across the African savannah.  The emu is slightly smaller, but looks somewhat similar.  But what on earth is a rhea?

A Common Rhea (photo: the wikipedia files)

Related to ostriches and emus, Greater Rheas are tall, long-legged, flightless birds.  They stand approximately four feet tall and are the largest bird found in South America.  Rheas, and other flightless birds, belong to a group called ratites.  Ratites do not have the bony protuberance on their sternum, called a keel, to which flight muscles attach.  Their wings are also very small for their body size, making them useless for flight, but useable for balance and helping to change direction.

A Greater Rhea (photo: the wikipedia files)

As I mentioned earlier, Rheas lay large eggs, and lay many at a time.  Rheas do not choose one mate for life like some other species.  Instead, one male will mate with many different females.  Those females (as many as twelve of them) all lay their eggs in the same nest.  The male, who built the nest for those females, then incubates the eggs and raises the chicks all by himself.  The females wander off on their own during this time…so much for maternal instincts.
Imagine the omelet you could make with this Rhea egg (photo: Gay Schroer)

Speaking of eggs, Rhea eggs are collected for food (imagine the omelet you could make with those!), and the birds themselves are hunted for their meat, skins, and feathers.  While Rheas are not endangered, they are considered to be Near Threatened.  Hunting regulations have restricted the harvesting of eggs and birds for commercial uses, but sport hunting is still a threat to these birds.

Next time you’re at the World Bird Sanctuary, be sure to wander into the Environmental Education Center and take a look at that egg display.  When someone asks you just what a Rhea is, you can tell them.

Submitted by JoHanna Burton, World Bird Sanctuary Naturalist

No comments: