Species Profile: Bermuda Petrel

Survival in the Face of the Big One

On September 5, 2003, Bermuda experienced the full force of Hurricane Fabian, possibly the strongest storm to hit the island since 1899. Fabian had its origins south of the Cape Verde Islands, and strengthened into a hurricane by August 30.

Fabian took an ominous turn to the north towards Bermuda by September 2, passing over the island as an intense Category 3 hurricane three days later.

The large eye of Fabian brushed Bermuda's western coastline, placing the island in the dreaded northeast quadrant of the eyewall (the strongest part of the storm) for more than three hours. During this period, peak sustained winds of 121 m.p.h. were experienced, with gusts to 150 m.p.h. Fabian was a large, relatively slow-moving storm, producing hurricane- force gusts for ten hours over Bermuda.

Fabian's impact on Bermuda was severe, with thousands of buildings damaged and power and phone service heavily disrupted. There was also loss of life as four people were swept with their cars to their deaths off the heavily damaged causeway which connects the east end of Bermuda to the main island. The effect of this hurricane on Bermuda's vegetation, parks and nature reserves was substantial, with the exposed Castle Islands Nature Reserve, home of the fabled Bermuda Petrel, also known as the Cahow (recently designated as Bermuda's national bird) being hard hit. There were large cliff falls and erosion of rock faces on all of the Castle Harbor Islands, with the cliff nest sites of Bermuda's population of White-tailed Tropicbird (Phaethon lepturus catsbyii) being severely affected. Bermuda supports the largest Atlantic population of this species at more than 2,000 nesting pairs. Preliminary surveys on some of the Castle Harbor Islands indicate that as much as 40% to 50% of all tropicbird nest sites may have been destroyed.

The hurricane had a devastating impact on the four exposed Cahow nesting islands. The Cahows were not on the islands as they do not return to their nesting burrows until mid to late October, however, nine of the 70 active nest burrows were destroyed when large sections of two of the islands collapsed or were washed away. In addition, nearly 50 of the heavy concrete nest burrow lids, which permit observation of the nest chambers, were swept off the islands and the burrows filled with rocks and debris. Many of these nest lids were recovered from the ocean bottom off the islands with the help of volunteers using scuba and snorkeling equipment, and it was relatively simple but labor-intensive to replace missing lids and clean out debris washed into burrows.

However, repairs to the Cahow nesting islands were held up by repeated rough conditions as three other strong hurricanes passed south or east of Bermuda. Hurricanes Isabel, Juan and Kate passed close enough to produce large surf around the nesting islands, making landings impossible for up to a week at a time.

The most difficult part of the repairs to the nesting areas involved the construction on new groups of artificial nest burrows to replace the nest sites destroyed These were built out of concrete as close as possible to, but at a higher level than the original sites to make them more resistant to damage during storm events. These pairs may, however, be disrupted for a few years because of their fidelity to the original nest locations. Sound attraction techniques will be tried to lure disrupted pairs more quickly to the new, safer sites.

As of the writing of this article (December 2003), the Terrestrial Conservation Crew of the Bermuda Department of Conservation Services has all but finished the construction of the new burrow complexes, which has involved mixing more than 4,000 lbs. of cement on nearby Nonsuch Island, transporting the concrete by boat in buckets to the island and landing on the sharp rocks in a strong ocean swell, then hoisting the buckets by rope to the tops of the islands. It is a tribute to the workers and volunteers that assisted in the repair and recovery that all work was essentially complete by the time the first Cahows began to arrive for the nesting season on October 17. This nesting season will require additional monitoring work to determine the extent to which the hurricane has afffected the Cahow breeding population and the overall recovery of the species.