ZOO-ology column: Egrets exemplify energy efficiency
By Judie Farnsworth
May 27, 2012 at 12:27 a.m.
Updated May 28, 2012 at 12:28 a.m.
I'm sure you've noticed these relative newcomers to our Texas landscape.
Thinking back, some may remember a time when they were rarely or never seen. They're taking care of business in a beneficial, efficient manner. In the spring and summer, look in almost any pasture with grazing animals and you're likely to see them - cattle egrets.
They originated in Africa and Asia and their nearly worldwide range expansion is rather phenomenal. How did they get here?
The mechanics of their initial journeys are a mystery. We know they were sighted in parts of South America in the 1800s. They moved into North America beginning in the 1940s and began spreading along the Gulf Coast states from Florida. The first sightings in Texas were in the early 1950s. Their range now includes nearly all 50 states, as well as Newfoundland.
It's quite interesting to note that while they've grown in numbers and greatly expanded their range, they haven't caused problems within native wildlife communities. The reality is they're beneficial in the unused niche they have filled.
Cattle egrets are opportunistic feeders (adaptable - making the most of what is available.) Their major prey items are grasshoppers and cattle-associated flies. They occasionally eat ticks, earthworms, fish and small birds. Frogs and toads are often fed to their chicks.
They're terrifically energy efficient creatures finding 95 percent of their food by following grazing animals and farm machinery. This is a beater, follower (attendant) association. The cattle egrets (attendants) grab insects flushed from grasses, grain and cotton fields by grazing animals/farm machinery (beaters).
You may have seen them hitching a ride on the back of a horse or cow - maybe the pastoral version of meals on wheels. They're welcomed guests helping to control flies and insects that plague cattle and damage crops. They often follow fires and may fly into the smoke to catch insects moving from the area.
There is a large summer breeding population in Texas. Since they nest later than our native egrets and herons, they are mostly non-competitive. They're colonial (social) birds, nesting and roosting in large groups. Swampy and wooded areas are used as well as coastal islands.
Cattle egrets are quite beautiful in their breeding plumage with buff colored feathers on their crown, breast and back. An eligible bachelor displays with a beak up position while waving sticks.
If he and his twiggy offerings are accepted, he'll bring more while the little woman arranges them in a loose, but satisfactory nest. An abandoned nest may be used or dismantled for its parts.
There appears to be a rash of devious stick snatching between birds during this time. Both birds care for the young, but once the chicks are on their own, the birds will become solitary once more.
The cattle egrets we see migrate to areas in Mexico or along our coast for the winter. Enjoy them while they're here.
Birds are fabulous creatures. The opening of The Texas Zoo's remodeled aviary is scheduled for the end of June. Check our website (texaszoo.org) for more details and visit often.
The Birder's Handbook by Ehrlich, Dobkin and Wheye
CATTLE EGRET | The Handbook of Texas Online| Texas State
Judie Farnsworth is a longtime volunteer at The Texas Zoo specializing in educational programs.