Rediscovery of a Missing Bird
A Bermuda Petrel
You may recall how excited ornithologists were in 2004 when evidence suggested that an ivory-billed woodpecker, a species believed to have been extinct for sixty years, was found in Arkansas. Note that, despite much effort including the use of electronic equipment designed to record the woodpeckers' calls, no widely accepted confirming evidence has been produced since the initial report.
That sixty years is dwarfed by an earlier return from what was believed to have been extinction, a story well told by Buffalonian Elizabeth Gehrman in her new book, "Rare Birds" (Beacon). Here is a precis of her story.
The Bermuda petrel or cahow (pronounced CA-how with the a sounding like the a in mash) was so common when sailors first approached Bermuda in the 16th century that the volume of their cries gave the island its early name, Devil's Isle. Estimates number the birds in the millions.
Unfortunately, those early visits also began the demise of these birds. By the mid-1500s pigs had been introduced to the island. This was standard procedure for sailors: the pigs would breed and be available for harvest when their ships passed that way again. With less purpose, cats, dogs, goats and especially rats were also introduced. As if those scavengers weren't enough threat to the birds, humans arrived in 1609, the first a group of castaways. As one report had it, they proceeded to "take, kill, roaste and eate" the petrels. Another report tells us, "We dried and salted more than a thousand. The men ate them all the time, and they were so plentiful that four thousand could be killed at the same spot in a single night."
The result: the last report of the cahow was in 1612 and it was believed to be extinct by about 1625. Like the dodo and the passenger pigeon the world had apparently lost another species.
But then in 1951 after a lapse of almost 400 years the birds were rediscovered by a team led by the famous American ornithologist Robert Cushman Murphy. (Only in 1993 were the first cahows seen at sea.)
Why then were they not found for so long?
The life history of the cahow addresses that question. This species spends its first five years wandering at sea, rarely even resting on the water and probably even sleeping in flight. Only after that long period do the adults return each year briefly to their home site to breed. Their noisy courtship takes place during the darkest nights. Once the female is inseminated, the pair departs once again to allow the female's single egg to mature in her body.
When the time comes for delivery, the pair, bonded for life, returns to nest in an underground cavity. The egg is laid and incubated alternately by the parents until it hatches to produce a chick that requires only a few more days before it is ready to fly. Then the parents simply leave, the chick climbs out of the nest into the light and after a few attempts flies off to start the cycle of life once again.
So we have rare visits to underground nesting sites on tiny rock outcroppings that are difficult for humans to explore, all this combined with only nighttime activities by the petrels. It was for these reasons that this species went so long unrecorded.
But there were hints that the birds were around. Gehrman describes how inhabitants of small islands in the Bermudan archipelago and Portuguese fishermen were familiar with the cahows, but in Bermuda's highly stratified society, these people were considered second-class citizens and their observations went unrecorded.
Shortly before the 1951 discovery, Fred Hall, then a Coast Artillery captain but later director of the Buffalo Museum of Science, played a small role in this story. He heard "cries from the outer islands" and found other evidence of the birds presence but failed to publish his observations.
In Gehrman's lively story, David Wingate shares center stage with the Bermuda petrel. As a 15-year old, Wingate was with Murphy when the bird was rediscovered and he devoted his life to its protection. It is estimated that there are now about 250 cahows breeding in Bermuda largely due to his efforts.-- Gerry Rising