Herring Gull (Larus argentatus)

Herring gull (Larus argentatus argenteus)

(http://www.arkive.org/herring-gull/larus-argentatus/)

  • Name: Herring gull
  • Latin: Larus argentatus
  • Classification: Bird
  • Origin: Northern hemisphere
  • Lifespan: Up to 30 years

Taxonomy

  • Kingdom: Animalia (animals)
  • Phylum: Chordata (vertebrates)
  • Class: Aves (birds)
  • Order: Charadriiformes (waders, gulls and auks)
  • Family: Laridae (gulls)
  • Genus: Larus (gulls)
  • Species: Larus argentatus (herring gull)

Apperance

  • Length: Males – 60-67cm (24-26in) Females – 55-62cm (22-24in)
  • Weight: Males – 1,050-1,525g (2.3-3.36lb) Females – 710-1,100g (1.6-2.4lb)
  • Wingspan: 125-155cm (49-61in)

The adults have a grey back and upper wings with a white head and under parts. The wingtips are black with white spots (known as ‘mirrors’). They have a yellow bill with a red spot underneath. They have bare yellow skin around the pale eyes and the legs are usually pink but can become yellowish. The males and females have identical plumage so are not incredibly sexually dimorphic, although the males tend to be slightly larger than the females.

The juvenile and 1st winter birds are mainly brown with dark streaks and have a dark bill and eyes. The 2nd winter birds lose some of their dark features and have a whiter head and under part with less dark streaking. The 3rd winter birds have plumage similar to adults but still retain some of their juvenile features such as brown feathers in the wings and dark markings on the bill.

Immature herring gull resting on ice during its first winter
First winter

(http://www.arkive.org/herring-gull/larus-argentatus/image-A22842.html)

This slideshow requires JavaScript.

  • Swallow-tailed gull (Creagrus furcatos) -LEAST CONCERN-
  • Ivory gull (Pagophila eburnea) -NEAR THREATENED-
  • Laughing gull (Leucophaeus atricilla) -LEAST CONCERN-
  • Silver gull (Chroicocephalus novaehollandiae) -LEAST CONCERN- 

Habitat & Distribution

Herring gulls tend to live and breed in coastal areas and is commonly seen perching on cliffs overlooking the sea to decrease the risk of predation by terrestrial mammals. Their habitat requirements seem to include shelter from the prevailing winds, a food source and protection from predators. These birds can also be found in seaside towns, nesting on the rooftops and eating the refuse.

These birds are commonly seen throughout the northern hemisphere as their range starches across countries such as Russia, Alaska and northern Canada. The herring gull can be found further south although they tend to breed in the northernmost areas of their range.

Map showing the distribution of the Herring gull taxa

(http://www.bbc.co.uk/nature/life/Herring_Gull)

Diet

Herring gulls are omnivorous, opportunistic predators with their diet consisting of marine invertebrates, fish, small birds, eggs, carcasses and human refuse (the refuse will often make up as much as half of the birds diet). When foraging at sea, they will follow whales, fishing boats and groups of fish and squid to find food and will then form a scattered group when feeding. Herring gulls will often dive for food but struggle to go further than 1-2m deep due to their natural buoyancy. These birds will also eat nuts, fruits, grains and roots.

Herring gulls have proven themselves to be intelligent feeders as they have been observed dropping shellfish from great heights in an effort to break the shell open and will also use bread as bait to lure in and capture small fish. Also, herring gulls can often be seen drumming their feet against the ground in a comical manner for long periods of time. This causes vibrations to ripple through the soil which drives earthworms to the surface. These vibrations are thought to mimic those produced by digging moles which causes this escape behaviour in the worms.

Herring gulls are also fully capable of drinking seawater although they seem to prefer fresh water when presented with the choice. They have specialized glands above the eyes which removes excess salt from the body. This salt is then excreted as a solution through the nostrils.

Behaviour

Flocks of herring gulls have a very loose hierarchy which seems to be based on size and physical strength. Adult males are generally dominant over females and juveniles, although the females can become dominant when choosing nesting sites. Communication of this species is highly developed and very complex which includes the use of body language as well as vocal calls.

Unlike other flocking birds, herring gulls do not partake in social grooming and tend to keep physical contact between individuals to a minimum. They tend to maintain safe distances from each other and scrapping can occur if they get too close, although serious injuries usually do not occur.

Reproduction

During courtship, the female will intrude on the male’s territory and approach him in a submissive posture and making begging calls. If the male approves of her, he will respond with an upright posture and mewing calls. Then the two will dance, making head swaying movements for each other. After all this, the male will then regurgitate food and if accepted by the female, the two will copulate.

2-4 eggs are laid in a clutch although the average is three. They are laid in nests on the ground or on cliff edges which are defended fiercely by both parents. The eggs themselves are olive coloured adorned with dark blotches and are incubated for 28-30 days.

When the chicks emerge, their natural instincts tell them to peck the red spot on the adults beak to indicate hunger, which will cause the mother or father to regurgitate food. The young can fly after 35-40 days and fledge at 6 weeks. The parents will continue to feed the chicks up to 12 weeks to 6 months of age.

Herring gull chick and egg hatching

(http://www.arkive.org/herring-gull/larus-argentatus/image-A22774.html)

Adaptations

  • The herring gull has striking white plumage. This is to signal to others where food is found on the open ocean. This enables an individual to see exactly where food is and also aids the survival of large numbers of these birds.
  • The herring gull has large webbed feet which allows it to manoeuvre effectively while sitting on the sea surface.
  • The herring gulls have natural buoyancy which stops them from sinking into the sea. However, because of this, herring gulls can’t dive very deep, only up to 1-2m.
  • A herring gull chick is led by instinct to peck the red spot on an adults beak when it is hungry. This encouraged the adult to regurgitate food, which aids in the survival of the chicks.

Threats

These birds are threatened by coastal oil pollution and oil spills which can poison individuals and render many incapable of flight. Herring gulls are also susceptible to avian influenza (bird flu) and are hunted in Denmark. Breeding colonies of these gulls are predated upon by great black-backed gulls, harriers, corvids, herons, racoons and foxes.

Conservation

  • IUCN Status: Least Concern

The herring gull is protected under the Conservation of Wildlife (Jersey) Law 2000 which makes it illegal to intentionally injure or kill any gull or to take, damage or destroy an active nest or its contents. Jersey also requires anybody to have an official licence to cull gulls.

In Britain, they are protected by many conservation groups including EC Birds Directive, Birds of Conservation Concern 3, Birds of Conservation Concern in Ireland 2 and it is also listed as a UK BAP species.

Fun Facts

  • Male: Cock
  • Female: Hen
  • Young: Chick
  • Group: Flock, Colony
  • The herring gull is named so because of an original belief that herrings were its favourite food.
  • The long, territorial call of the herring gull is also known as the laughing call.

References

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s