The following article was written by Raymie Miller, a Summer Habitat Intern at the Woodland Dunes Nature Center.
Since starting my job here at Woodland Dunes, I have made a habit of going to the beach after work every day. Not to go swimming, or sunbathing, or whatever else it is that most people do at beaches. I bring a pair of binoculars, a camera, and a spotting scope to look through the flocks of gulls. The lakeshore of the Two Rivers and Manitowoc is a renowned area for birders all across the wider Western Great Lakes region for its concentrations of gulls, among which rare gull species are sometimes found. Little, Glaucous-winged, Laughing, Franklin’s, Ivory, and Short-billed Gulls are among the species that have been found here over the years. My hope is, if I check the beach enough times, I can find one of these rarities.
In a manner of speaking, I have not been successful. The only “rare” gull I have yet found was an Iceland Gull, which is a rare sighting here in summer but in winter would not be unusual at all. Yet, were you to show a list of the gulls I have been seeing to someone in the region forty years ago, you would be met with shock. Yes, I have been seeing Ring-billed, American Herring and Bonaparte’s Gulls, and lots of them. Nothing unusual there. But among these flocks of gulls, I have seen quite a number of another species, the Lesser Black-backed Gull.
Lesser Black-backed Gulls are a common species across much of the Old World, ranging widely across Eurasia and Africa. This is a common and well-known species in these areas, but they were not documented anywhere in North America prior to 1927, when a single bird was found in New Jersey. After 1927, they were occasionally, but rarely, reported from North America exclusively along the East Coast until the 1980s. Starting in the 1980s, records of this species started to ramp up. Rather than single individuals, entire flocks were being found in places like New England and the Maritime Provinces. Records started showing up further south and further inland than ever before. Wisconsin got its first record of the species in 1980, with a single bird being found in Milwaukee.
North American records have continued to increase ever since then. Today, Lesser Black-backed Gull has been recorded in every single US state and Canadian province, and is a common species on the Atlantic coast from Labrador to Puerto Rico. Records here on the Great Lakes continue to increase at a rate that is even visible from year to year. This species has become a regular sight on Lake Michigan beaches since the late 1990s, but only in this decade have large flocks, such as the ones I have been seeing on our Two Rivers beaches, become a common sight. In Wisconsin, records away from Lakes Michigan and Superior remain rare, but who knows how long this will remain the case. I found one in an agricultural field near Stevens Point last spring, currently one of the only reports of this species in the central part of the state.
The Lesser Black-backed Gull is a fascinating reminder that ecosystems are in a constant state of flux. Species communities change over time, and sometimes rapidly. Even many of our common everyday species – Cardinals, raccoons, opossums, coyotes, red foxes and Red-bellied Woodpeckers are not believed to have occurred in this region historically. This change in species communities over time is an overlooked part of regular ecosystem function over time, just often difficult to observe on the timescale of a single human life. Lesser Black-backed Gulls stick out both because of the rapid timescale of their expansion and also the distance across which they dispersed. Cardinals and raccoons didn’t come from that far away, just from other parts of North America. Lesser Black-backed Gulls came from – actually, where did they come from?
This is another mystery relating to this species – where did they come from? To date, Lesser Black-backed Gulls have never once been recorded nesting in the United States or Canada. Most Lesser Black-backed Gulls seen in North America are seen in winter, when nearly all individuals present are adults. During the summer, all of the adults seem to disappear off to somewhere, but juveniles stick around and loiter on beaches mixed in with other gulls which are locally breeding (these juvenile gulls are the ones I have been seeing at the beach this summer). The adults clearly go somewhere to nest over the summer, but where is it?
The initial theory was somewhere in western Europe, with birds migrating across the Atlantic twice a year. But this doesn’t quite make sense, as there is no banding data supporting this theory. Scientists frequently attach small metal rings called bands to the legs of birds to track their individual movements. Each band contains a unique serial number, allowing a different scientist in another part of the world to recognize an individual bird and know where it came from. Lesser Black-backed Gulls in Europe are frequently banded, but only two European banded Lesser Black-backed Gulls have ever been found in North America, so most of our gulls do not seem to be coming from Europe.
Many Lesser Black-backed Gulls nest in Siberia, but the populations there are visually distinct and do not match the birds currently being seen on the East Coast and Great Lakes (although Siberian Lesser Black-backed Gulls are certainly occasionally seen on the West Coast, including some hanging around among nesting gull colonies in Alaska). Thus, that can be ruled out for the vast majority of our North American Lesser Black-backed Gulls.
Starting in the early 1990s, shortly after Lesser Black-backed Gull records really started ramping up in North America, this species was documented nesting in Greenland for the first time. Today, this species continues to nest in Greenland, but not in numbers that seem to account for the number of birds being seen in North America. In the end, it seems likely that, somewhere out there in the Canadian or Greenlandic wilderness, there is a large undiscovered colony or colonies of Lesser Black-backed Gulls. Thus, the Lesser Black-backed Gull is also a fascinating example to show that even among the Birds of North America, one of the best studied groups of organisms in the world, there are still some mysteries.
