Your getting a lot of mixed answers... never mind my opinion, I'm just going to tell you the facts!
The principal legislation dealing with the protection of birds is the Wildlife and Countryside Act 1981. This makes it illegal to intentionally capture, injure or destroy wild birds or interfere with an active nest or its contents.
(this is for scotland, hmmm....)
However, the law does recognise that, in some circumstances, control may be necessary against particular species of birds. Under section 16 of the Wildlife and Countryside Act 1981, the Scottish Executive annually issues general licences. These authorise the killing or taking of certain species of wild birds, including Feral Pigeon, Herring Gull, Lesser black-backed gull and Great black-backed gull for the purpose of:
protecting any collection of wild birds (licence SEGEN/09),
preserving public health, public safety, or air safety (licence SEGEN/10), and
preventing the spread of disease and serious damage to livestock or agriculture (licence SEGEN/22)
The fourth licence, (SEGEN/23) licences authorised persons to use semi-automatic weapons to kill or take the above mentioned species of birds. However, authorised persons must ensure compliance with relevant firearms and public safety legislation.
Unless an authorised person acts in accordance with the terms of the licence, he commits an offence. The Council would only be justified in taking action against pigeons or gulls in North Lanarkshire if it could be satisfied that, to do so, would preserve public health or safety or would prevent the spread of disease.
The Council would for example be justified in taking action to destroy and, or remove the eggs or nest of a pair of roosting gulls where the location of their roosting site would give rise to concerns over public safety, should they display aggressive behaviour.
In other circumstances where the killing of birds and the taking of their eggs would not be justifiable, the proofing of roosting sites may provide a viable option for control. Various options for control are examined later.
I believe that all gulls are protected by the countryside act 1981.
Well in theu UK they are protected by the countryside act. You can only humanely kill them if thhey are nesting on your building, you will have to use a deterent.