02/04/18 (Protected) Pest Of The Week – Great Black Backed Gull
Appearance Great Black-Backed gulls (Larus Marinus) are the largest gulls in the world, measuring about 64 to 79cm (25″ to 31”) from bill to tail with a wingspan of about 1.5 to 1.7m (4’11″ to 5’7”). The adult great black-backed gull has a white head, neck and underparts, dark grey wings and back, pink legs and yellow bill.
Breeding This gull breeds singly or in small colonies, sometimes in the middle of a other gull colonies. Young adult pair formation occur in March or April. The following spring the same birds usually forms pair again, meeting at last year’s nest. Only if one of the birds doesn’t arrive, the other bird begins looking for a new mate. Usually the lonely bird does not breed in that season.
They make a lined nest on the ground often on top of a rocky stack, fallen log or other obstructing object which can block the contents from the elements. However on roofs in urban environments, last years nest is often used over and over again. The female lays usually three eggs sometime between late April and late June. When only two eggs are found in a nest, the reason is almost always that one egg, for one reason or another, has been demolished. Also it takes around one week for the female to produce the three eggs, and the rumination doesn’t begin until all three eggs are laid. Hence all three chicks are hatched the same day. The birds are usually successful in bringing all the three chicks up.
The eggs are greenish-brown with dark speckles and blotches. Both parents participate in the incubation stage, which lasts for approximately 28 days. During this time, the birds attempt to avoid being noticed and stay silent. The breeding pair are devoted parents who both take shifts brooding the young, defending the nest and gathering food. Young great black-backed gulls leave the nest area at 50 days of age and may remain with their parents for an overall period of around six months, though most fledglings choose to congregate with other immature gulls in the search for food by fall. These gulls reach breeding maturity when they obtain adult plumage at four years, though may not successfully breed until they are six years old.
Diet Like most gulls, great black-backed gulls are opportunistic feeders. They will investigate any small organism they encounter and will readily eat almost anything that they can swallow. They get most of their dietary energy from scavenging, with refuse, most provided directly by humans, locally comprising more than half of their diet. The proliferation of garbage or refuse dumps has become a major attractant to this and all other non-specialized gull species in its range. Like most gulls, they also capture fish with some regularity and will readily capture any fish smaller than itself found close to the surface of the water
The Problem Many people who have gulls on their property find they cause a nuisance and commonly cited problems include:
Noise, caused by calling gulls and by their heavy footsteps
Mess, caused by their droppings, fouling of washing, gardens and people
Damage to property, caused by gulls picking at roofing materials and by nests which block gutters or hold moisture against the building structure
Birds can dive and swoop on people and pets. This usually occurs when chicks have fallen from the nest and adult birds attempt to prevent them coming to harm by frightening away potential threats
Blockage of gas flues, valley and parapet gutters by nesting materials. The former can have serious consequences if gas fumes are prevented from venting properly, or if flooding occurs as a result of blocked gutters
Control The principal legislation dealing with the control of birds is the Wildlife and Countryside Act 1981. Generally it is illegal to capture, injure or destroy any wild bird or interfere with its nest or eggs. However, only when there is a need to preserve public health or public safety authorised persons may take, damage or destroy herring gull nests; or take or destroy herring gull eggs. No action may be taken unless the authorised person is satisfied that alternative methods to resolve the problem, such as scaring and proofing, are ineffective or impracticable. All owners/occupiers of buildings which have, or may attract, roof nesting herring gulls are strongly urged to provide the building with deterrent measures suitable to the individual building. If as many owners/occupiers as possible apply deterrent measures to their buildings, it may be possible to reduce or break up the colonies of birds.
For advice or further information on Greater Black Backed Gulls in Edinburgh, Glasgow, Aberdeen, Dundee or Perth, call GRAHAM pest control today and we could help
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