Herring Gull (Larus argentatus) and Lesser Black-Backed Gull (Larus fuscus) ID Monika Reiss, PhD student, Liverpool John Moores University

The following provides details for the generalist reader about how to identify the two species of gull, herring gull (Larus argentatus) and lesser black-backed gull (Larus fuscus) in my research. More in-depth information about Merseyside’s gulls can be found at https://merseybirders.webs.com/gullidentificationpage.htm.

Herring gull (Larus argentatus)

General information

Herring gulls are big seabirds, 50 to 70 cm in body length and up to 150 cm in wingspan. It takes them four years to mature, and they can live up to 30 years. The plumage of the adult male and female is identical; however, males are usually bigger. The juvenile herrings gull’s plumage starts out as mottled brown, and gradually develops into the adult bird’s white and grey plumage.

Herring gulls are breeding as well as wintering on Merseyside, so we can see them the whole year round as they do not migrate to warmer climates. They regularly reside near ponds in Sefton Park and Princes Park, as well as on the tidal flats of the River Mersey during low tide, which is where they forage most often. They also like to forage on open, green spaces like parks or farmlands where they can easily detect predators. Urban gulls, during the breeding period, prefer to build their nests on high buildings or houses, as it is easier for them to find discarded food near human dwellings. They often sit on buildings in the city centre and wait for the opportunity to feed on human refuse, which is very often easier to acquire than their natural food.

Appearance

Adults

The adult herring gull’s head is white during the summer breeding period; during the winter, it changes to white with grey streaks. Their beak is yellow with a red dot at the tip. Adult gulls have a very pale iris with black speckling. The ring around their eyes,  called the orbital ring, may vary from yellow to a pale orange colour.

The adult’s wings are light grey on top, paler beneath, and have black tips with white spots or ‘mirrors’, as they are known. When they are stationary and they put their wings together, it gives the illusion of a grey ‘back’. Their neck, belly and bottom are completely white. Herring gulls have long, pink legs; however, some subspecies can have slightly yellow legs, and, the yellow-legged gull (Larus michahellis) was once considered to be a race of herring gull.

 Juveniles
Juvenile herring gulls have grey and brown plumage, and each year their plumage develops a little to become the silver grey back and white neck/underparts of the adult bird. Their bills are mainly black during the first year, and go through a similar development to their plumage so that, by the fourth year, the birds have the adult’s yellow beak with red spot. Their eyes are almost completely black with no distinguishable orbital ring colour. Between the 3rd and 4th year moult, their iris becomes paler and the eye develops the orbital ring. Their legs are pale pink. After the 4th summer, they are sexually mature adults.

Herring gull 1^st winter.   Photo credit: ©2015 Jonathon Woolf

http://www.jwoolfden.com/

Herring gull 2^nd winter.  Photo credit: Charles J Sharp

Sharp Photography, sharpphotography, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=51991783

Herring gull 3^rd winter. Photo credit: ©2015 Jonathon Woolf

http://www.jwoolfden.com/

Herring gull breeding adult. Photo credit: ©2015 Jonathon Woolf

http://www.jwoolfden.com/

 Lesser black-backed gull (Larus fuscus)

General information

Lesser black-backed and herring gulls belong to the same genus, Larus; therefore, they are quite similar. In fact, for a long time scientists thought they were the same species. The lesser black-backed gull’s body is between 50 and 60 cm long, and their wingspan is up to 140 cm; they are slightly smaller than herring gulls, and their wings are a darker grey. They also take four years to mature; and the juveniles’ plumage is again browner and more mottled than the adults’. Similar to the herring gulls, the plumage of male and female lesser black-backed gulls is the same; the only visible difference between the sexes is that males are bigger than females. These gulls come to Merseyside mostly for the duration of the breeding period, from April until August; during the winter months they used to migrate – mostly to African countries – but some birds now stay here year-round. Similar to the herring gulls, lesser black-backed gulls forage on uncovered tidal flats of the River Mersey, parks and farmlands. Additionally, gulls living in urban areas like Liverpool often forage on human refuse, and can be seen in our city centre and other areas where humans or their refuse congregate.

Appearance

Adults

The adult lesser black-backed gull’s head is completely white, the eyes are pale yellow with a red eye ring, and their beak is yellow with a red dot at the end. Their  wings are slaty grey, with the exception of small white spots or ‘mirrors’ on the wingtips, similar to the herring gull. Their neck, belly and bottom are completely white. Lesser black-backed gulls have slender, yellow legs. Adults again have a pale iris with speckling; females usually have more speckles than males. The colour of their orbital ring ranges from dark orange to bright red.

 In their winter plumage, they have the ‘streaky’ head and neck of the herring gull.

Juveniles

Juvenile lesser black-backed gulls have grey and brown plumage, and each year their plumage develops a little to become the dark grey back and white neck/underparts of the adult bird. Their bills are black during the first year, and go through a similar development to their plumage so that, by the fourth year, the birds have the adult’s yellow beak with red spot. The juvenile’s iris is black, similar to that of juvenile herring gulls. During the first three years, their orbital ring is no different in colour than the rest of the plumage on their head. After the 3rd moult (sometimes it happens earlier), their eyes grow lighter and their orbital ring becomes a red colour. Their legs are pale pink at first, which gradually changes to yellow as the bird matures. After their 4th summer, they are adults.

 

Lesser Black-backed gull 1^st winter. Photo credit: Don Faulkner

https://creativecommons.org/licenses/by-sa/2.0/deed.en

Lesser Black-backed gull 2^nd winter. Photo credit: Don Faulkner

https://creativecommons.org/licenses/by-sa/2.0/deed.en

Lesser black-backed gull 3^rd winter. Photo credit: Cassia Tofano

Lesser black-backed gull breeding adult. Photo credit: Jason Leung

Edited by Debra Williams