Changes in factors that affect Integrated gull management
Mark Wenman, NPTA Technical Manager
I often compare a building owners timing for commencing integrated gull management to my approach to buying Christmas presents. We know that it’s best and most cost effective to do this six months earlier, but often it’s the day before the big day- the day when a gull drops the first material to nest!
Changes to gull nesting distribution
As you may know, we do not call the main species of gulls in the UK, ‘seagulls’. The two main species that may affect our customers premises have changed their habits over the last few decades. The herring gull (Larus argentatus) and lesser black-backed gull (Larus fuscus) have not had a truly accurate census. Estimates by NatureScot, Natural England and the BTO (British Trust for Ornithology) show that there is a strong bias towards urban nesting, even as high as an 80%- 20% distribution. Compare this to the Kittiwake (Rissa tridactyla). This species has not changed its range and will always nest on cliffs with limited urban nesting. I’ve been involved with advising on Kittiwake sites in Newcastle, East Yorkshire and Suffolk and these are always facing the sea or a river leading from this, such as the Tyne.
Why has this happened?
Historically, herring gulls and lesser black-backed gulls fed extensively at sea, and on discards from fishing vessels and fisheries. Changes in the fishing industry have meant that gulls must travel further offshore or inland to obtain their food. The range of these two gull species can be up to 40 miles. They are very opportunistic feeders and adaptable, so this has enabled them to adapt to urban food sources. You will have seen gulls stealing human food or becoming established at food manufacturing sites where small feeds are available from the waste bins or finished good spillages. Taking this a stage further, some of the largest populations of gulls are on or near waste sites or landfill sites. They have very few natural predators so populations can thrive.
If you’ve taken a walk along a cliff path during late spring, the conditions can be far harsher than that on a roof of a factory in an urban industrial estate.
This is the other main reason that the large gull species have become established inland. A building may have a roof with a parapet wall or air handling unit that provides the perfect sheltered location for a gull to nest and nurture its juveniles.
Have gulls adapted biologically?
A simple answer is no, because they do not need to.
The maximum recorded lifespan of both the herring gull and lesser black-backed gull is 30-35 years. They will nest on the same roof every year if the conditions remain favourable. Juvenile gulls take 4 years to reach maturity whereupon they will likely nest on the same roof and if not, nearby.
What are the risks from gulls?
There are many, hence why we are asked to advise on Integrated gull management.
During the nesting season (March to August) gulls can be aggressive in the defence of their eggs and juveniles and this will be at a distance away from the nest. This is also true when they try and take foods from unsuspecting humans. Persons working on a roof may be perturbed by gull activity, at risk from slips, trips or falls.
Gull nesting material may block roof gulleys. The damage from gulls pecking a roof substrate or air handling unit coating can be substantial. Gulls can also damage unprotected food stuffs and packaging.
We often discuss the disease risk from feral pigeons. Gulls also present a risk. Bacteria such as Salmonella, Campylobator and Escherichia coli can be present in droppings due to feeding habits on landfills for example. Aspergillus may be a risk. Fleas, mites and flies may be present in a nest which can then migrate into a building.
Are gulls protected?
Under the ‘Wildlife and Countryside Act 1981’, all birds are protected.
The herring gull is on the ‘red list’ meaning that they are at a risk of endangerment. The lesser black-backed gull is on the ‘amber list’ meaning that this species is facing threats from habitat loss and other factors.
No gulls are included within any open bird licences in the UK. An integrated gull management plan must put a gull’s welfare at the centre. It is illegal to intentionally kill, take or injure gulls, take or destroy their eggs, or damage or destroy any gull nests while they’re in use or being built.
How can we implement a gull management plan?
This can be very complex and site specific. Therefore, please ask and we will advise.
The key point linking back to my first statement is that there is still time. Nest building for both species can commence in March, but weather variations can affect this.
The first stage is getting the building owner on side to manage food sources and hygiene factors.
It is possible to deter established gull activity prior to nesting with an extremely diligent, professional falconry program that utilises other techniques. Examples of these are handheld lasers and alarm (distress) call systems. An integrated approach is essential.
Gulls will use key points of a building for scouting food sources and loafing. The tops of parapet walls, roof ridge lines or dormer roofs can be proofed to deter gulls becoming established.
Some sites will have populations that are so persistent that the only option is to consider encapsulating a roof or area in a supported and maintained net system. Alternatively, parallel gull wires can be installed to deny gull access. The former system can be especially at risk of wind load and ice/ snow pressure so it’s essential to design a robust solution. Again, we can assist you with this.
Please contact us on technical@npta.org.uk If you would like further information or advice.
