The Lesser Black-backed Gull (LBBG) breeds in Europe, Iceland, Greenland and parts of Asia, and was first identified in North America in 1934. Since the 1990s it has established a winter presence in North America such that it is a somewhat common sighting where gulls gather. There are at least 5 recognized subspecies, with the graellsii thought to be the most abundant in North America. The LBBG should be the first to be considered when identifying a large (larger than Laughing), dark-backed gull in Texas.
Structure
The LBBG is smaller and slimmer than the Herring and larger and bulkier than the Ring-billed. (LBBG on the left in the photo below). As can be seen in the silhouettes below, compared to Herring the LBBG sports a long, attenuated back-half (behind the legs), with long primary projection. The Herring is larger, more truncated and is bulkier in the belly and behind the legs. These structural differences become more important when assessing immature gulls. The Ring-billed is smaller and daintier, with a rounded head and smaller bill.
The relative size and structure of the LBBG are compared in the next group of photos with the Ring-billed, Herring and Laughing.
The Bill & Head
In LBBG the bill is shorter and thinner than that of Herring (right in the comparison below), with slightly less hook at the tip and slightly less gonydeal angle. The LBBG bill has been described as “bullet-like” and this seems to be particularly noticeable in sub-adult birds.
The head in the LBBG is usually more arrowhead-shaped, than round or square, as in the sub-adult below (left). This characteristic seems more pronounced in sub-adult LBBGs – adult LBBGs usually seem to have more filled-out heads.
The bills of adults (pictured below) are yellow with a red gonydeal spot, but often in basic there are large patches of black and red elsewhere on the bill as well. In alternate the gape and orbital ring take on a red color. In basic these colors fade and the head shows streaks which can be quite dense. The eye in adults is yellow and winter LBBGs often have a “punched-in-the-eye” look formed by dark feathers around the eye.
The typical LBBG structure is shown in the adult and 3rd-year gulls below. The LBBG has long, slender wings which jut out well-beyond the tail when perched. The body often has a chesty appearance as in the sub-adult below. Adults often seem to be more filled-out in the belly.
Plumage
Adult LBBGs are shown below and since they are only in Texas in winter (generally) most of my photos are of basic plumage.
The 3rd cycle gull shown in the series of photos below is the closest I’ve found to an LBBG in alternate plumage in Texas (Rollover Pass, Bolivar Peninsula, 4/26/23). The head is stark white, with no sign of streaking on the hind-neck and head, or black feathers near the eye.
Somewhat surprisingly, the LBBG shown below appears to be in alternate plumage even though the photo was taken in January (1/24/25, Bryan Beach, Texas).
Back Color
Like many large gulls, structure and plumage can vary amongst individuals. The back color, or rather the intensity of the black on the back, varies in adult LBBGs. In the composite photo below, a Herring (gull 1) is compared with three LBBGs (gulls 2-4). As demonstrated by these 4 photos, lighting conditions and camera settings are important considerations when assessing back color of gulls in photos. Lighting conditions must also be considered in the field with the naked eye.
In some instances the apprent variation in back hues may be because individual gulls are from different subspecies. Most sightings of LBBG in North America are of the graellsii subspecies. In these gulls the hue of the back contrasts with that of the primaries—the primaries are intense black, while the back is more charcoal-ish. In other subspecies such as intermedius, and in other gull species, the primaries and back are of similar hue. For these reasons, the hue of the primaries should be compared to that of the back when assessing a large, dark-backed gull. This practice may help to identify a dark-backed, out-of-range rareity like Slaty-backed Gull, Kelp Gull or Great Black-backed Gull.
Gulls 2 and 4 in the composite below seem to be LBBG of the expected graellsii subspecies. However, the back and primary hues of gull number 3 below ae equally dark and seem to match, so this gull (3) may be of the intermedius subspecies. The long primary projection and overall structure also supports this conclusion. However, the evidence of this one photo is inconclusive.
It’s also worth noting that gull 4 is slightly smaller, has a rounder head and perhaps longer wings. These are characteristics of female gulls, so gull 4 is likely a female LBBG. The size, shorter primary projection, and larger, anvil-shaped head suggest that gull 2 is a male.
In-Flight
In-flight the adult LBBG shows a black-and-white pattern reminescent of an inverse Swainson’s Hawk with black, or at least dusky, primaries and secondaries and white underwing coverts (covering the basal portions of the secondaries and primaries). The pink legs and feet are also sometimes evident in flying gulls.
The LBBG has long, narrow wings; narrower, especially at the base, than those of Herring.
As shown below, the ventral side of immature LBBGs can be quite dark. Also note the pale “windows” on the inner primaries of the sub-adult Herring which the LBBG usually lacks.
Additional flight photos of LBBG are shown below.
Identification of Sub-adult Gulls
Like most large gulls, LBBGs are progressively less tricky to identify as they age; the juvenile and 1st winter gulls are the most difficult, and the adult is the most straight-forward. The first line of identification of all gulls is relative size and structure. If possible, compare the unknown gull with known gull species. Next, review the structural clues of candidate species and compare them to that of the unknown gull as well as to known gulls. Finally, look for plumage characteristics appropriate for the age of the gull as well as the date of the observation.
Sub-Adult LBBG
Juvenile and 1st winter LBBGs can often be identified by their size and structure in comparison to known species such as the adult Herrings pictured below. (Both juvenile and 1st winter can be considered sub-adult plumages). Note that the LBBGs are smaller, more slender, more attenuated in the rear-half and have a more flattened, arrowhead-shaped head. A sub-adult LBBG is pictured with an adult Herring below.
A single sub-adult LBBG is pictured with 1 or more sub-adult Herring below.
Since their adult back feathers are quite dark, LBBGs are not as tricky to identify once their adult back hues begin to emerge in their 1st winter and beyond. In addition to the leaner, more long-winged structure, the LBBG’s all black bill at this age stands out; the Herring’s bills are beginning to get pink at the base. Note that each of the gulls pictured below has scapulars that stand out (in both color and in relief) from the surrounding feathers. These scapulars have recently emerged, indicating the beginning of the molt from juvenile to 1st basic plumage (aka 1st winter). The Herring’s scapulars are paler than their wing coverts, while the LBBG’s have a darker gray fringe, with a large brown center.
The darkening of the back of LBBGs continues as the gull grows into adulthood. Second and third (possibly 4th) winter LBBGs are shown below.
