Gulls may be commonly associated with the seaside but, in January, a Hertfordshire reservoir becomes a much-needed sanctuary for thousands of the endangered birds.

Hilfield Park Reservoir Nature Reserve is managed in partnership by Herts and Middlesex Wildlife Trust and, site owners, Affinity Water, to conserve and enhance wildlife. Situated between Elstree and Bushey, the reserve is a vital roost site for five species of gulls – Great Black-backed Gull, Lesser Black-backed Gull, Herring Gull, Common Gull and Black-headed Gull. Additionally, on most days throughout the colder months, small numbers of Mediterranean Gull, scarcely seen in Hertfordshire, come here to roost too. All of these birds may be uniformly recognised as ‘seagulls’ but scientifically there is no such thing – their common ground is that a majority of these species are struggling, with the red-listed Herring Gull topping the list for the highest level of conservation concern in the UK.

Gulls’ numbers have been in freefall since the 1970s due to habitat loss and scarcity of food sources. This has led to us losing around three quarters of the UK’s gull population over the last 55 years. The State of Nature Report 2023 delivered further gloom with a headline that 43% of birds are at risk of extinction.

The Trust works across the area to protect habitats, which are a priority for wildlife conservation and to reverse the alarming declines we are seeing in our local wildlife. Despite the damning statistics, there is hope for our gull population. In the past gulls only wintered locally, roosting on larger water bodies but Black-headed Gulls are now an established breeding bird in Hertfordshire and the number of breeding Lesser Black-backed gulls here is increasing.

Josh Kalms, People and Wildlife Officer at Herts and Middlesex Wildlife Trust, says:

“Recent counts conducted by volunteer surveyors at Hilfield Park Reservoir as part of the British Trust for Ornithology’s Winter Gull Survey identified that the total numbers roosting there have declined by approximately 60% in 30 years - 28,184 in 1994, 19,693 in 2004 and 11,794 in 2024. Despite this, the site remains the only gull roost in Hertfordshire and the most important refuge for roosting gulls in Hertfordshire and north west London.

 “Gulls need somewhere safe to spend the night and they find that refuge at Hilfield Park Reservoir. At this, the darkest time of year, gulls can spend up to 14 hours bobbing on the water, where predators are less able to reach them. As it begins to get light, they take flight and head off to feed on rubbish tips, arable fields and playing fields – some of these may be over 30 miles from their roost.

“As we’re heading to work or school in the morning, we might see or hear them flying overhead – witnessing them disperse in large numbers can provide the impression that all is well in the gull world, when we know that is really not the case. It’s why protecting habitats like this one at Hilfield Park is so important for nature’s recovery.”

Affinity Water is proud to actively manage this site alongside Herts and Middlesex Wildlife Trust, demonstrating a strong commitment to environmental stewardship and habitat enhancement. In 2023, Affinity Water provided essential funding to complete a major habitat restoration project at Hilfield Park Reservoir, enhancing the site’s wetland margins. This collaborative project significantly increased the habitat value for a wide range of wildlife, including dragonflies, damselflies, wading birds, Kingfishers, Bitterns — and, of course, gulls.

Sophie Mortimer, Biodiversity Manager at Affinity Water, says:

“Hilfield Park Reservoir is a shining example of how we actively manage our sites to enhance biodiversity as part of our commitment to protect and improve the local environment for current and future generations. We’re incredibly proud of the site’s significance, not only as a vital sanctuary for gulls of different species but also a valuable refuge for Black-necked Grebes. Our partnership with Herts and Middlesex Wildlife Trust is key to ensuring the continued protection and enhancement of this unique site.”

If you are interested in seeing the spectacle of the gull roost at Hilfield Park Reservoir first-hand, the Trust is running a ‘Gulls Galore’ event on 25 January 2025. For more information and to book, click here.