My Visit With an “Extinct” Bird

I HAVE always been fascinated by the variety and beauty of birds. While preparing for a visit to Bermuda, I came across a reference to a rare bird called the cahow. “The tiny surviving population of this species,” said one bird guidebook, are “confined to the Castle Harbour island group, the most remote part of Bermuda. Here they are under the strict surveillance and protection of a warden.”

My interest had been aroused! Determined to see this exotic bird for myself, I contacted Dr. David Wingate, Bermuda’s former conservation officer. He is now retired, but at the time he was also warden for the Castle Harbour island group. Dr. Wingate kindly allowed me to accompany him on a visit to the protected nesting area of the cahow.

A “Living Museum”

The Castle Harbour Nature Reserve lies near the main islands of Bermuda, which are situated in the Atlantic Ocean, about 570 miles [900 km] east of North Carolina, U.S.A. Nonsuch Island is the largest of nine small islands that make up the reserve. Nonsuch is about 15 acres [6 ha] in size and is located at the eastern end of Bermuda. Under Dr. Wingate’s direction, the island was turned into a “living museum” for the eventual reestablishment of Bermuda’s remaining native plant and animal species.

The day is clear and beautiful as we head out in Dr. Wingate’s tiny powerboat from Nonsuch to a nearby islet.  An osprey skims over the calm sea, the white feathers of its underwings reflecting the vibrant turquoise blue of the water. Beautiful tropic birds, called longtails in Bermuda, fly around excitedly in a courtship display, their outsize tail feathers waving up and down. While this sight would normally have been quite exciting for me, today I can think only of the cahow.

The “Extinct” Cahow Reappears

Dr. Wingate explains: “There were reports by early settlers of seabirds that returned to land only at night and only when they were nesting​—both characteristic of the cahow. At that time cahows numbered in the tens of thousands, but this changed. About the year 1560, the Spanish introduced hogs into Bermuda. This proved disastrous for the cahow population because the hogs ate cahow eggs and, probably, chicks and even full-grown cahows. Cahows were also an important part of the settlers’ diet. When rats were accidentally introduced into Bermuda in 1614, many more cahows died. The rats would swim out to the tiny islands where the cahows nested and eat their eggs and chicks. So by 1630 the cahow had been reduced from having a population of many thousands to being thought of as completely extinct.”

Over the drone of the boat’s motor, I ask: “How were the cahows rediscovered?”

Dr. Wingate replies: “In 1906, Louis Mowbray, a naturalist, found a live but strange-looking seabird on an island in Castle Harbour. It was eventually identified as a cahow. Later, in 1935, a fledgling cahow was found that had struck a lighthouse and died. And in 1945 a full-grown cahow washed up on the beach at Cooper’s Island, Bermuda. This was enough evidence to warrant an expedition to search for more specimens of this ‘extinct’ species. The expedition was led by Dr. Robert Cushman Murphy of the American Museum of Natural History and by Louis S. Mowbray, curator of the Bermuda Government Aquarium​—son of the Louis Mowbray who found the cahow in 1906.”

 Dr. Wingate smiles as he recalls: “How privileged I felt to be asked to join that expedition, especially since I was but a schoolboy of 15 with a great deal of interest in birds! That Sunday, January 28, 1951, was a day that has affected the rest of my life. I will never forget the elation on Dr. Murphy’s face when he and Mowbray succeeded in noosing a live cahow found in a deep crevice! The government immediately declared the islets in Castle Harbour a sanctuary for the cahow. Nonsuch Island was added to the sanctuary in 1961, and the next year, my wife and I moved there so that I could serve as its warden.”

“How many cahows did you find during that first expedition?” I ask as we draw near the nature reserve.

“Only eight nesting pairs were found in the first year,” he replies. “It was so difficult to locate the nests that it took ten years to locate the entire population, which at that time included 18 nesting pairs. After another 35 years of conservation, they had increased to a grand total of 52 pairs.”

Help From Man

“Cahows nest in burrows 6 to 12 feet [2 to 3 1⁄2 m] long, with a bend so that light does not reach the nest,” continues Dr. Wingate. “To provide more nesting sites, we started making artificial burrows. These were made by excavating trenches and then roofing them over with concrete. The nest chamber at the end of the burrow has a removable lid. This enables us to check the nests to see if an egg has been laid or hatched or if we have a failed egg. When a failed egg is abandoned, we can remove it for examination and try to ascertain what went wrong. In the mid-1960’s, DDT insecticide residue caused eggshell thinning  and resulting breakage. Now we are concerned that chemicals like PCB [polychlorinated biphenyl] may have the same effect. Although North America and Europe have banned PCBs, many developing countries have not.”

There are additional challenges. Dr. Wingate observes: “There has been an ongoing battle for nesting sites between the cahows and the more aggressive tropic birds. A cahow may choose a nesting site behind a shallow depression, and then a tropic bird will take up residence right at the entrance! The rude intruder will destroy the cahow’s egg or attack and kill the chick. Both species always return to their same nesting sites, so the problem continues year after year. To save the cahow, we began to place simple wooden baffles at the entrances of the cahow burrows. The baffles have an elliptical hole of just the right size to let the cahow in but exclude the slightly larger tropic bird. In this case, an eighth of an inch [3 mm] makes a life-and-death difference.”

In the Reserve

Finally, we arrive at the little island. Between ocean swells we carefully step from the boat onto the jagged rocks. To reach the nests, we must climb over steep, sharp rock formations. One nest is only accessible by ladder. This may be routine for Dr. Wingate, but for me, it is unique and exhilarating!

Dr. Wingate checks around each site, reading the evidence. Are the pairs still visiting their nests? Are there footprints leading in and out of the burrows? Are there any failed eggs? We find one failed egg, but since the parents have not yet abandoned it, Dr. Wingate leaves the egg there. Often, cahows will continue to incubate a failed egg, refusing to give up. Dr. Wingate also makes an unexpected discovery​—a chick where he had not even realized an egg had been laid! This find outweighs the disappointment of the unhatched egg.

That all such effort is worthwhile becomes evident when Dr. Wingate removes a lid from a burrow and I look down on a small, gray ball of fluff​—a cahow chick. Now and then the chick moves slightly, being disturbed by the light. In other burrows, I peer down and see an adult incubating an egg.

Dr. Wingate has come to the rescue of many chicks in trouble. A tropic bird attacked one chick and broke the chick’s bill. In desperation, Wingate glued the bill together. How surprised and pleased he was when the chick survived! Another time, he retrieved a frail chick that had been prematurely abandoned by its parents. He kept it in a box and raised it on a diet of shrimp, squid, cod-liver oil, and vitamins. Eventually, it was able to fly out to sea. So far, efforts to reestablish the cahow are slowly producing results. In fact, the cahow has been called a symbol of hope for conservationists around the world. Dr. Wingate’s goal is for Nonsuch eventually to house 1,000 pairs of cahows. Whether his dream will materialize, however, remains to be seen.

My visit with the “extinct” cahow makes me think. Surely, if the Creator notices when a common sparrow falls to the earth, would he not notice when an entire species has been endangered? (Matthew 10:29) How comforting to know that the time will come when human society will no longer threaten the existence of any species on earth!​—Isaiah 11:6-9.​—Contributed.

[Maps on page 16]

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BERMUDA

Nonsuch Island

[Picture on page 18]

A cahow inside a burrow

[Credit Line]

Jeremy Madeiros, Conservation Officer, Bermuda

[Picture on page 18]

The entrance of a cahow burrow

[Picture on page 18]

Dr. Wingate points to the baffle at the entrance of a cahow burrow

[Picture Credit Lines on page 16]

Jeremy Madeiros, Conservation Officer, Bermuda

Globe: Mountain High Maps® Copyright © 1997 Digital Wisdom, Inc.

[Picture Credit Lines on page 17]

© Brian Patteson

Jeremy Madeiros, Conservation Officer, Bermuda