Gull Identification Guide & Info

There are 5 common aerodrome species

 

3 x large gull species. Herring Gull, Lesser Black backed Gull & Great Black backed Gull

2 x small gull species. Common Gull & Black-headed Gull.

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• Herring Gull and Lesser Black-backed Gull most regular roof nesting species.

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• All species can communally roost together – outside the breeding season.

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• Breeding season is March to July/August.

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• Incubation period approximately 30 days.

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• Fledging period 8-12 weeks.

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• Large Gulls in particular are attracted to Landfill sites or other waste food locations

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• Small Gulls feed on sports and agricultural fields, sewage works (both species) and scavenge for food in urban and suburban environments (mainly Black-headed Gulls)

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• 38% of fatal birdstrike incidents worldwide involved Gulls (Thorpe 2012). 

 

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Herring Gull 
 
Average weight 1071g – high damage probability. 

In adult plumage silvery grey mantle, black wingtips with white mirrors.

Pink legs.  

Varying amounts of head streaking outside the breeding season.  

Aggressive, mean looking expression caused by large chunky bill and angular head shape.

Juvenile mottled brown plumage, dark wingtips and black bill. Adult plumage gradually acquired over a four year period. Adult mantle colour becomes apparent late in the first winter of life.  

In flight has a pale “window” near the bend in the wing when viewed against the light

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Lesser Black-backed Gull 
 
Average weight 931g – moderate damage probability.

Adult plumage has Slate-grey mantle, contrasting with black primary tips.

Yellow legs.

Looks shorter legged and longer winged at rest than other large gulls.

Heavily streaked head outside the breeding season, white head during breeding season.

Juvenile similar to juvenile Herring Gull but sleeker shape and weaker looking bill. On average darker headed, some showing a dark masked effect around the eyes. 
 
 
Great Black-backed Gull 
 
Average weight 1560g – high damage probability

Adult plumage has a jet-black mantle with no contrast with the primary tips.

Pink legs

Long-legged stance with relatively short rear end.

Proportionally large, chunky bill.

Very little head streaking at any time of the year.

Juvenile has more spangled upper parts, large black bill emphasized by the whiter head. 
 
 

Black-headed Gull. 
 

Average weight 289g - low damage probability.

Generally the commonest aerodrome gull species.

ALL Black-headed Gulls show a white leading edge panel to the wing in flight.

Red legs and bill in adult plumage, slightly washed out in colour outside the breeding season.

Chocolate brown head (looks black) in breeding season.

Dark ear spot outside the breeding season (Aug/Sept – Feb/March).  

Juvenile like adult winter plumage with paler bill with dark tip and mottled brown feathers in the upperwing. 

Can form large communal roosts on large flat roofs or larger waterbodies.

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Common Gull 

 

Average weight 407g – low damage probability.

Adult plumage superficially similar to adult Herring Gull with silver grey mantle, dark wing tips with white mirrors.

Adults have yellow bill (with no red pot) and yellowish-green legs, brighter in the breeding season.

Dark “beady” eye.

Delicate looking bill and rounded head shape give gentle expression compared to Herring Gull.

Varying amounts of head streaking in winter (see right hand 3 birds in picture below), white head during the breeding season.

Juvenile is mottled brown above with the adult mantle colour becoming apparent during the first winter. This species takes two years to reach full adult plumage. 

Can form large communal roosts on large flat roofs or larger waterbodies.
 
 
Additional species 
 

These species are unlikely, but not impossible to occur on the airfield. At any time of the year there is the chance of Mediterranean Gull which is a small gull, slightly larger than Black-headed Gull. Also there is an outside chance of Yellow Legged Gull or Caspian Gull predominately outside the breeding season (but not exclusively). These are both rare large gulls with very subtle differences to Herring Gull. In winter the rare Glaucous Gull and Iceland Gull do occur in the UK, particularly at landfill sites or communal roosts. Identification details can be found in most good identification guides or can be sent on request should it be suspected that one of these species has occurred.