Nature up close: Cattle egrets, masters of emigration

The range of cattle egrets has expanded as humans expanded the range of their livestock.

Verne Lehmberg

By "Sunday Morning" contributing videographer Judy Lehmberg.

It has taken me a while to realize it, but I have been following cattle egrets around my whole life. Although I've been bird watching for about 45 years, and have seen more than 2,500 species, there isn't any animal I've followed as closely as cattle egrets. I have no illusions about their part in this odyssey. They don't know, or care, if I exist, but the feeling isn't mutual. I admire cattle egrets because they have not only survived in a world dominated by humans, they've thrived. 

Cattle egrets (formerly named buff-backed herons due to their breeding plumage) are native to parts of Spain, Portugal, sub-Saharan Africa, and tropical and subtropical Asia. They are the only animal known to have successfully moved from the Old World to the New World on their own, without any aide from humans. No one knows exactly how they got to the New World, but we do know they were first seen in the Guianas in northeastern South America in 1877.  Some ornithologists speculate they were blown from their native Africa across the Atlantic by trade winds, or possibly during a storm.

Cattle egrets follow large grazing animals such as rhinos, Cape buffalo and cows, snatching insects and small vertebrates stirred up by those animals. They also eat parasites from the same animals. They have moved to new areas and colonized them successfully because they've found empty niches.

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Two cattle egrets on a rhinoceros in Tanzania.

Marcy Starnes

An animal's niche is basically what they do for a living. Cattle egrets have successfully moved into new habitat where they are the only animal that follows cattle and other large herbivores eating the insects they flush. Their success is due not only to their ability to colonize new places but also because we have expanded the range of domestic cattle so much in the last 150 years. Now, along with their original territory, they also live in most of South America, Central America, the West Indies, the United States, parts of Canada, Indonesia, Australia, and New Zealand. They have learned how to thrive within the habitat we have created for cattle.

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Great egret with wings spread.

Verne Lehmberg

I first became aware of cattle egrets while working on my undergraduate degree in wildlife science at Texas A&M in the early 1970s. Our ornithology professor took us on a field trip to a cattle egret rookery being studied by Ray Telfair. Cattle egrets (the subject of Ray's Ph.D. dissertation) nest communally with waterbirds in trees either in, or surrounded by water.  The rookery we visited was in a large group of trees surrounded by waist-deep water. Ray had us don waders and go from nest to nest weighing cattle egret chicks. I always wondered about the accuracy of our measurements because every single baby we picked up defecated on us as a defense mechanism. 

I also wondered where the alligators were as we stood in the murky water listening as male alligators made their deep, rumbling mating calls. Thankfully that last question was never answered.

Several years later while working on my M.S. in biology, I wrote a paper on cattle egrets. The fact that they had traveled across the Atlantic Ocean on their own, and appear to be the only bird to have successfully done that in recorded history, fascinated me. I first read about their arrival in South America in a book by James Bond. (More on that later.*) After much research, I found out cattle egrets and I had some things in common.  They first arrived in Texas in 1954; I got there in 1956. They began moving north from Texas and first made it to Idaho in the mid-1970s, which is when I first visited that stunning state. Later, I was lucky enough to live and work in South Africa where cattle egrets were busy expanding their range. Then I went to Costa Rica, and so did they -- then Puerto Rico, then the Virgin Islands. My travel list is still growing, and so is theirs.

In a very real sense the cattle egret's success has been as a result of how humans have changed this Earth. I'm sure, if they thought about it at all, cattle egrets would consider that to be a great success. Whether the land and the many species excluded from cattle country would agree is an entirely different question.

[And no, I did not mean that James Bond. The original, real James Bond, was an American ornithologist who wrote "Birds of the West Indies." Ian Fleming, who created superspy 007, was an avid bird watcher living in Jamaica in the 1950s. As he searched for a name for the hero of his spy novel "Casino Royale," he found a book, "Birds of the West Indies" by James Bond. Fleming asked the real James Bond about using his name and Bond said he was "fine with it."

Fleming wrote to the real Bond's wife: "It struck me that this brief, unromantic, Anglo-Saxon and yet very masculine name was just what I needed, and so a second James Bond was born." He referenced Bond's work when he based a bird sanctuary on Dr. No's island; and he later gave Bond a first edition of "You Only Live Twice" which he inscribed: "To the real James Bond, from the thief of his identity." In 2008, almost 20 years after Bond's death, that book sold at auction for $84,000. 

And filmmakers gave the ornithologist a nod as well; in "Die Another Day," actor Pierce Brosnan peruses a copy of Bond's field guide.]

Judy Lehmberg is a former college biology teacher who now shoots nature videos.

       
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