ALWAYS IN SEASON/ Mike Jacobs: What gull? That can be hard to tell
For the past couple of weeks, it's been hard to miss the flocks of gulls, coursing as they do over parking lots and farm fields.
What are these gulls? It's hard to tell. The gulls are a complicated and confusing bunch.
About 50 species occur worldwide, perhaps as many as 55 depending on how you count. About half of these show up in North America.
The profusion of species is only part of the problem with gulls. Most are multi-year birds; they take time to mature, some as much as four years. Each year brings a different plumage, and so 50 species soon turns into more than 100 different plumages. That is why gull identification guides tend to be large tomes. "Gulls of the Americas" (Houghton-Mifflin, 2007) runs to more than 500 pages. "Gulls: A Guide to Identification" (Buteo Books, 1987) includes 192 pages of text and 547 photographs. These are excellent sources if you really want to "get into" gulls.
For us, the task of sorting out the gulls is somewhat simplified. While the Red River Valley is rich in individual gulls, it is relatively poor in gull species. Only five occur here with any regularity, and one species probably accounts for more than half the individuals that are encountered.
This means a large proportion of the gulls we are likely to see are of that one species, ring-billed gull. Others, in diminishing order of abundance, could be Franklin's, Bonaparte's, California or herring gulls.
These would be easy enough to identify in adulthood. Franklin's is one of the so-called "hooded" gulls. In adults, the head is black, and black extends over the neck onto the upper chest. Bonaparte's also has a black head, but the color doesn't extend quite so far back on the bird's body; hence, it is regarded as a "masked" gull. While these distinctions may seem trivial and the labels enigmatic, they are quite useful in determining to which species an individual bird belongs.
But only for adults.
Franklin's gull is a common breeding species in North Dakota. It is a familiar bird, often seen in freshly tilled fields, where it gleans insects. This species has an interesting distinction among gulls; it is the only North American species that crosses the equator in migration. Franklin's gulls spend the winter along the coast of Chile and Peru.
Bonaparte's gull is unusual, too. It nests in trees. Since the Red River Valley is not a forested area, Bonaparte's gull doesn't nest here. It is a common nesting species in the Canadian shrub forest, however, and the nearest Bonaparte's gull nest is probably 150 miles or so from Grand Forks. This makes the species a common migrant through our area, both spring and fall.
Our most abundant gull, the ring-billed gull, is a white-headed gull distinguished from others of the type by its smaller size and the black ring near the tip of its bill. This is diagnostic, but it's hard to see. Better marks are the bird's small size and crisp lines. Richard Crossley, in "The Crossley Guide" (Princeton 2016), calls this a "clean" gull, in contrast to the rather mottled, blotchy and undependable plumage patterns of some other gulls. Juveniles show quite a pattern of black and white spots on the back, rather like a checkerboard, and sub-adults show quite a lot of brown.
Two other white-headed gulls often are encountered here — though not so frequently as the ring-billed. Both California and herring gulls are larger, much larger in the case of the herring gull, which is half again as large as the ring-billed gull. The herring gull is a migrant here, occurring in small numbers both spring and fall, and thus worth watching for. Generally, herring gulls stick to large bodies of water; they aren't likely to be seen foraging in a farm field. California gulls nest in North Dakota. Up close, a red spot on the bill will separate the California gull from the ring-billed gull definitively. Plumage holds clues, too. Sub-adults are brown and appear smudged, all together less clean than ring-bill gulls.
Gulls are great wanderers, and several other species have been recorded in Grand Forks County, and even more along the Missouri River below Garrison Dam, where water is open all winter long.
For these rarities, I refer you to the identification guides noted earlier.