IBP BIOLOGIST PETER PYLE AND COLLEAGUES DISCOVER NEW SEABIRD SPECIES IN THE HAWAIIAN ISLANDS

A research team led by IBP Biologist Peter Pyle has, for the first time in decades, found a new bird species in the United States. Based on a specimen collected in 1963 on Midway Atoll, Northwestern Hawaiian Islands, Peter and colleagues at the Smithsonian Institution have described a new species of seabird, Bryan's Shearwater (Puffinus bryani). Differences in measurements and physical appearance compared to other species of shearwaters, along with analysis of its DNA, has confirmed the specimen as a species new to science. It is the smallest shearwater known to exist. Where this species breeds remains a mystery, however.

Biologists found the species in a burrow among a colony of petrels on Midway Atoll during the Pacific Ocean Biological Survey Program in 1963, and originally identified it as a Little Shearwater (P. assimilis), a species known to breed only in subantarctic waters of the southern Pacific Ocean. However, when Peter recently examined the specimen (see photo below) he found that it was too small to be a Little Shearwater and that it had a distinct appearance.

Above: Bryan's Shearwater specimen collected on Midway in 1963.

“It did not seem to fit any other shearwater species in size and appearance," Peter said, "the closest being Boyd's Shearwater, a species that breeds in the Azore Islands of the Atlantic and would be unlikely in the middle of the Pacific.”

Subsequent analysis of its DNA by Andreanna Welch and Rob Fleischer of the Smithsonian Conservation Biology Institute’s Center for Conservation and Evolutionary Genetics confirmed that it is an entirely new species. It differs genetically to a greater degree than found between most other species of its genus, and is relatively distantly related to Boyd's Shearwater. Based on this DNA evidence, researchers estimate that the Bryan’s Shearwater separated from other species of shearwaters more than 2 million years ago.

Peter and his colleagues still do not know where Bryan's Shearwaters breed. Shearwaters and other seabirds often visit nesting burrows on remote islands only at night, and the breeding locations of many populations remain undiscovered. Individual seabirds from colonies also often 'prospect' for new breeding locations, often far from existing colonies. On Midway, for example, prospecting seabirds have been found with known breeding colonies restricted to the tropical southern Pacific Ocean and the Indian Ocean. Thus, Bryan's Shearwater could conceivably breed anywhere in these ocean basins or even farther afield.

“We don’t believe that Bryan's Shearwaters breed regularly on Midway or other Northwestern Hawaiian Islands, based on the extensive seabird work in these islands performed during the Pacific Seabird Project,” Peter said.

Given that Bryan's Shearwaters have remained undiscovered until now they could be very rare, possibly even extinct. There are observations and photographic records of other small shearwaters in the North Pacific Basin as recently as 2005 and scientists are now evaluating whether or not these observations may be of Bryan's Shearwaters and seeing what additional information might be learned about their breeding grounds, at-sea distribution, and seasonality. One of these observations was of an individual found in a burrow on Midway in December 1990 which appeared also to have been a prospecting bird (see photo, below).

Above: Possible Bryan's Shearwater, found in a burrow on Midway Atoll in December 1990. Photo by Reginald David.

Entirely new species of birds have rarely been discovered since most of the world's 10,000 plus species (including about 21 other species of shearwaters) were described prior to 1900. The majority of new species described since the mid 1900s have been discovered in remote tropical rain and cloud forests, primarily in South America and southeastern Asia. The Bryan's Shearwater is the first new species reported from the United States and Hawaiian Islands since the Po'ouli was described from the forests of Maui in 1974. The Po’ouli was last seen in 2004 and is now probably extinct.

Conservation implications

"The best conservation strategy for Bryan's Shearwaters at this time is to discover and protect primary breeding locations and to protect other breeding sites where they may potentially breed, such as Midway," Peter says. "Introduced mammals such as rats and cats are among the greatest threats to seabird colonies and it will be important to keep potential breeding islands as free as possible from such predators." Rats were removed from Midway in 1997 and this has led to large increases in seabird populations there, so perhaps conditions may be better there now for establishing a new colony. Last year a pair of prospecting short-tailed albatrosses bred on Midway for the first time.

About the name

Bryan's Shearwater was named after Edwin Horace Bryan, Jr., who was Curator of Collections at the B. P. Bishop Museum, Honolulu from 1919 until 1968. Bryan participated in several biological expeditions in the 1920s, including the Tanager Expedition to the Northwestern Hawaiian Islands in 1923-1924. He was the author of many publications on Hawaiian insects and birds between 1926 and 1958, and wrote several popular books on astronomy and star-gazing from Hawaii. He is Peter Pyle's maternal grandfather.

Further reading

The research described here appears in the current issue of the journal Condor.

Pyle, P., A. J. Welch, and R. C. Fleischer. 2011. A new species of shearwater (Puffinus) recorded from Midway Atoll, Northwestern Hawaiian Islands. Condor 113(3):518–527.

Click here to read the research paper.

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