It sometimes seems hard to believe that so many mysteries still remain within the natural world, including within the most well-known group of wild creatures: birds! But new discoveries of all sorts greet us daily, leaving us continually spellbound.

One of the latest such discoveries is so new that it’s only been alluded to on social media, as far as we know.  It involves a set of seabird species whose very existence was essentially hidden in plain sight until quite recently. That’s because what we once considered to be a single species—the band-rumped storm-petrel—is now being considered a group of closely related and similar-looking separate species with a variety of differences that are slowly being elucidated.

Birders – and just about anyone who has spent time on boats offshore – know about storm-petrels. They are small agile seabirds that spend most of their time on the wing, low over the water. Across the world, there are at least 45 species of storm-petrels. Some are all dark; others, dark with a white rump and light band on the wing. Still others have white bellies and lighter gray uppersides. Trying to identify the different species of storm-petrels from the deck of boat, even in calm weather, is notoriously difficult. Making them even more challenging to study, all storm-petrels nest on islands, often the remotest and most complicated to access islands. To top it off, they nest in burrows underground and come to the nesting islands only at night!

Right here in Maine, we have Leach’s storm-petrels nesting on a number of islands (35 known in the 1990s) beginning in April, with young birds known occasionally into October. During this period, the adults are not often seen near the nesting islands but can be found feeding well offshore during the day.

Wilson’s storm-petrels, on the other hand, are often seen within sight of land along the Maine coast, especially in July and August. Unlike Leach’s storm-petrels, these birds are spending their non-breeding season with us. They nest on sub-Antarctic islands during our winter which is, of course, summer in the Southern Hemisphere.

Both Leach’s and Wilson’s storm-petrels are essentially brown birds with white rumps, looking a bit like large, dark swallows from a distance to the uninitiated. With some experience, differences in their shape, flight style, and other characteristics can make them readily identifiable most of them time.

Band-rumped storm-petrels are also largely all dark with a white rump. They nest on remote islands off Europe and Africa in the Atlantic and on islands in Japan, Hawaii, and the Galapagos in the Pacific (maybe other, unknown locations as well). Today these birds are referred to as the band-rumped storm-petrel complex because there may be six separate species in the Atlantic and four in the Pacific.

Birds referred to as band-rumped storm-petrels have become increasingly understood to be found along the East Coast of the U.S., often well-offshore, from Florida to Massachusetts. The increase in sightings comes as a result of a surge in offshore birding interest and organized boat trips over the last 40 years or so.

Maine has yet to have any widely accepted record of the species, including any photographic evidence, but there have been at least a couple of possible sightings. It seems likely only a matter of time before one of the band-rumped storm-petrel complex is photographed in Maine waters.

The fascinating new discovery that we saw on social media involved one of these band-rumped storm-petrel species that has been provisionally called Grant’s band-rumped storm-petrel. It was tracked from a winter breeding site in the Canary Islands, eventually making its way to summer off the East Coast of the U.S., possibly (though not confirmed) as far north as the southern edge of the Gulf of Maine. Presumably the researchers will continue to get more data from more birds of the various possible band-rumped storm-petrel species, and we will learn the amazing stories of the journeys of these cryptic and mysterious birds.

We can’t wait for the next discovery!

Jeffrey V. Wells, Ph.D., is a Fellow of the Cornell Lab of Ornithology and Vice President of Boreal Conservation for National Audubon. Dr. Wells is one of the nation's leading bird experts and conservation biologists. He is a coauthor of the seminal “Birds of Maine” book and author of the “Birder’s Conservation Handbook.” His grandfather, the late John Chase, was a columnist for the Boothbay Register for many years. Allison Childs Wells, formerly of the Cornell Lab of Ornithology, is a senior director at the Natural Resources Council of Maine, a nonprofit membership organization working statewide to protect the nature of Maine. Both are widely published natural history writers and are the authors of the popular books, “Maine’s Favorite Birds” (Tilbury House) and “Birds of Aruba, Bonaire, and Curaçao: A Site and Field Guide,” (Cornell University Press).