Bird Fact Friday – the Lesser Black-Backed Gull

Adapted from pages 266 to 273 of Gulls of the World:

The Lesser Black-Backed Gull is a four-year gull, and resembles a dark-backed, more slender version of Herring Gull, with rounder head and slightly thinner bill that appears less blunt-tipped and slightly drooping. They have long, slender wings are often held lowered when relaxed. Their head and underbody is whitish with dark streaking to mottling and dark eye-mask, while their central hindbelly and vent may lack dark spotting. The darkest of these birds have rather uniform brown head and underbody. Meanwhile, their upperwing is dark brown with blackish flight feathers, only rarely with indication of paler inner webs to inner primaries. They have two solid dark wing-bars, formed by blackish centres to greater coverts and secondaries, and an underwing that is blackish-brown to barred grey-brown in contrast to paler flight feathers. Finally, their rump is white with dense dark spotting reaching upper mantle as slight paler wedge against darker scapulars, and their tail is black with narrow white bases and spots along edges of t6; sometimes with more extensive white at base and narrower black tail-bar.

A gull

An adult Lesser Black-Backed Gull (intermedius). It’s a rather dark individual
with blackish upperparts, almost concolorous with wing-tip. Photographed by the author in Copenhagen, Denmark.

In flight, they are dark enough to be mistaken at range for juvenile skua (especially Pomarine, which is similar in size and dark overall plumage). The majority retain juvenile plumage in first part of autumn, unlike Yellow-legged, Caspian and many Herring Gulls, which from Sep have renewed mantle and scapulars and have slightly worn coverts. They breed colonially along coasts and on islands, locally on islands in lakes and rivers, on moors and on buildings.

There was a large increase since the 1940s with the extension of breeding range from 1920, so it is able to manage competition with Herring Gull. Since the 1990s, they have been breeding in Greenland; they probably also breed in North America, where scarce visitors to East Canada and USA. Most of the European population is migratory, but some remain near breeding sites to winter in milder parts of West Europe. Birds leave breeding sites from late July, with several stops during southward journey. Most winters are spent in the West Mediterranean and Atlantic coastline between the South Iberian peninsula and Mauritania, with some reaching southwards to interior West Africa and Gulf of Guinea coasts.

Gulls of the World
By Klaus Malling Olsen

With more than 50 gull species in the world, this family of seabirds poses some of the greatest field identification challenges of any bird group: age-related plumage changes, extensive variations within species, frequent hybridization, and complex distribution. 

Gulls of the World takes on these challenges and is the first book to provide a comprehensive look at these birds. Concise text emphasizes field identification, with in-depth discussion of variations as well as coverage of habitat, status, and distribution. Abundant photographs highlight identification criteria and, crucially, factor in age and subspecific field separation. Informative species accounts are accompanied by detailed color range maps.

Gulls of the World is the most authoritative photographic guide to this remarkable bird family.

  • The first book to provide in-depth coverage of all the world’s gull species
  • More than 600 stunning color photographs
  • Concise text looks at variations, habitat, status, and distribution
  • Informative species accounts and color range maps

 

 

 

This post is part of a series, explore additional posts here<< Bird Fact Friday– Black-tailed GodwitBird Fact Friday — Pallas’s Gull >>