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