Clemson University researchers went on a trailblazing expedition among an international team of seabird experts to capture black-capped petrels at sea for the first time and outfit the endangered birds with satellite transmitters.
This groundbreaking work is part of a larger effort to better understand the distribution and ecology of the seabirds, which come to land only during the breeding season and are known on Hispaniola as “diablotín” or “little devil” because of their eerie call and the sound produced by air moving over their wings during nocturnal flights.
Ranked as endangered by the International Union for Conservation of Nature and proposed for listing as threatened under the U.S. Endangered Species Act, black-capped petrels were feared extinct until their rediscovery in 1963. Today, the population is estimated between 1,000 and 2,000 birds based on observations of birds at sea, but to date only 80 nests have been located.
“These seabirds spend most of their lives at sea, flying over the open ocean in search of food,” said professor Patrick Jodice. “These tags will tell us which parts of the ocean these birds use, which in turn will help us understand the threats they face while at sea. We hope that the petrels might lead us to undiscovered nesting sites on new islands as well, but even if that does not occur, the at-sea data will be incredibly important to conservation efforts.”
Through the participation of the U.S. Geological Survey South Carolina Cooperative Fish and Wildlife Research Unit, housed in Clemson’s forestry and environmental conservation department, Jodice and research associate Yvan Satgé had central roles in the effort. The American Bird Conservancy led the expedition, with Brad Keitt and Chris Gaskin of the Northern New Zealand Seabird Trust conceiving the idea and designing the field protocols.
The team also included Brian Patteson and Kate Sutherland of Seabirding Pelagic Trips, who have 30 years of experience leading pelagic seabird tours out of Hatteras, North Carolina, and guided the team aboard the Stormy Petrel II to the best areas to find black-capped petrels.
The Clemson team will serve as the lead on all data management and data analysis. Regular updates about the satellite-tagged birds may be seen on an interactive map hosted on the scientists’ website.
Aboard a small inflatable boat launched from the nearby Stormy Petrel II, a two-person capture team negotiated the Gulf Stream waters off the coast of North Carolina. The team lured birds to an area by taking advantage of the birds’ highly developed sense of smell, which leads black-capped petrels to far-off foraging opportunities.
The researchers placed bait in the water — in this case, a floating cage packed with “chum,” a pungent and thawing block of fish guts — and then it was just a matter of waiting for the birds to arrive. Once the birds were within about 10 meters, the team used a custom-made net launcher to capture them in mid-air. The team measured, banded and released 10 black-capped petrels with transmitters between May 8 and 14 using this technique.
“It is quite remarkable to think that you can head 30 miles offshore and expect an endangered seabird to fly within 10 feet of you — close enough to catch with a net,” said Keitt, ocean and islands program director at the American Bird Conservancy. “Some said it couldn’t be done and to be honest we were all concerned that we might be disappointed.”
Just five breeding sites for the black-capped petrel are known, all on the island of Hispaniola (three in Haiti, two in the Dominican Republic). Radar surveys strongly suggest that the species breeds on Dominica as well, and scientists remain hopeful that birds may also breed on other islands, such as Jamaica and Cuba.
“The few nests we have observed with remote cameras in the Dominican Republic are often depredated by mongooses or other introduced predators, such as cats and rats,” Satgé said. “It is critical that we act quickly and step up conservation at the known nesting sites as well as any new sites we discover as part of this study.”
Jodice and Satgé have been also involved in other research and conservation efforts for this endangered species. In 2014, they conducted the first-ever tracking of black-capped petrels, tagging birds at nest sites in the Dominican Republic and publishing a scientific paper in Endangered Species Research that detailed the first foraging tracks for the species and revealed some previously unknown use areas at sea.
That research was likewise funded through efforts by the American Bird Conservancy, the same core partnership as the most recent project. With funding from the Neotropical Bird Club and BirdsCaribbean Dave Lee Fund, Jodice and Satgé also returned to the Dominican Republic in 2018 to deploy a new type of tracking device and collect additional foraging tracks.
“We are also working on a habitat analysis of known nest sites to help better focus nest search efforts,” Jodice said. “Although the current tracking effort hopes to result in the location of nest sites, there are many other aspects of the research that are important. These tracks will result in the most expansive and unique dataset for black-capped petrels at sea and will inform on potential threats in U.S. and international waters. For example, although these petrels are thought to occur primarily in the western north Atlantic, in late July we observed one individual as far east as the mid-Atlantic ridge.”
These two approaches — studying birds at sea and at nests — both address critical conservation needs to help scientists fully understand the ecology of the species.
“This is an amazing bird all around,” said Jennifer Wheeler, co-chair of the International Black-capped Petrel Conservation Group and with the group BirdsCaribbean. “The world thought it extinct, yet this bird has hung on in Haiti, a country facing overwhelming environmental degradation. It is a symbol of persistence and hope. It is tremendously exciting to think that this project may lead to undiscovered breeding areas for the species and new opportunities to engage in on-the-ground conservation activities to benefit it.”
The American Bird Conservancy works with partners to protect and minimize threats at breeding areas for black-capped petrels and continues to urge the United States to sign on to the international Agreement on the Conservation of Albatrosses and Petrels, which works to coordinate activities that benefit these birds.
The South Carolina Cooperative Fish & Wildlife Research Unit is supported by U.S. Geological Survey, South Carolina Department of Natural Resources, Clemson University and the Wildlife Management Institute. The research was funded primarily by a grant to the American Bird Conservancy by the Mohamed bin Zayed Species Conservation Fund.
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