Tern and Black Headed Gulls on raft
Bird monitoring in Lee Valley Regional Park
Release date:
10 August 2026
Lee Valley Regional Park’s 26 mile corridor of diverse landscapes provide a variety of habitats for migratory and resident birds.
Understanding how different species move through, choose breeding locations and inhabit the Park has taken years of careful monitoring. This research builds valuable insight into the habits of individual species and improvements and adjustments to habitats that lead to increased and returning numbers.
Data is collected from recordings by visiting birdwatchers, targeted bird surveys and bird ringing. Species-specific and project-specific survey work often goes hand in hand with ringing, and together these activities have contributed to an impressive and long-running dataset for the birdlife of the Lee Valley.
Bird ringing allows individual birds to be tracked, helps monitor survival, longevity, productivity, migration and behaviour. These findings continue to shape how we manage features for target species, monitor change and measure our successes.
One of the Lee Valley’s oldest bird ringing groups has been active at Rye Meads Nature Reserve since the late 1950’s. More recently the Walthamstow Wetlands Group has been formed, and studies a range of urban species.
Recent Projects
In recent years a number of specific projects and studies on a range of key species have been undertaken by bird ringers in the Park with support from staff. These include monitoring Grey Heron and Little Egret colonies at Glen Faba and Walthamstow Wetlands, monitoring of Barn Owl boxes installed by the Authority and the monitoring of Common Tern rafts at Fishers Green. The spread of Red Kite has seen successful breeding at Gunpowder Mills and in 2026 a pair nested near one of our campsites. Both Barn Owl and Red Kite are Schedule 1 birds and require a special licence to visit the nest and ring the chicks which are held by the ringers.
Common Tern and Black-headed Gulls
Common Tern are ground-nesting birds that choose gravelly, sparsely vegetated open sites where they form simple nests in a shallow scrape in the gravel. In the Lee Valley, they first began breeding on the banks of active and exhausted gravel workings. In 1963, the first artificial nesting raft, created to mimic their natural breeding sites, was installed at Rye Meads. Since then, artificial rafts have become an important part of Common Tern conservation in the valley and the Authority and our partners have provided artificial breeding rafts at a number of sites from East India Dock Basin in the south to Nazeing in the north of the park. Up to 100 pairs have nested in the valley in the past with Fishers Green being one of the strongholds which saw around 40 pairs in 2009. In the same year the first pair of Black-headed Gulls nested on the rafts at Fishers Green.
By 2026 the Black-headed Gull breeding colony had increased to around 170 pairs and their rapid takeover of the rafts has contributed to the decline in Common Tern numbers alongside other potential causes such as predation by larger gulls. Small numbers of Common Tern are still able to breed alongside the Black-headed Gulls and in 2026 we had ten pairs on the rafts on Seventy Acres Lake at Fishers Green. The on-going monitoring of the rafts has shown that Black-headed Gulls seem to preferentially choose to nest alongside fences on the edges of the rafts – leaving space in the centre of the rafts for the Common Tern. This careful monitoring of the changing population dynamics has led to the installation of larger rafts to provide more internal space for the Common Tern. The designs are constantly being refined and the ongoing ringing effort will be crucial to monitoring their impact.
Alongside the usual metal rings used in bird ringing the Black-headed Gulls and Common Terns in the valley are also colour ringed with a distinctive yellow plastic ring featuring a unique black code. The colour rings are much more visible than the metal rings and enable birdwatchers to easily identify and report individual birds giving a unique insight into their movements.
We now know many of the young gulls go to Spain in their first year and stay there for a while until they are ready to return to the valley to breed. Some do multiple journeys: Southern Colour Ringing Group - Black-headed Gull EZ58358
Common Tern are known to winter on the west coast of Africa and do not come back to the valley to breed until they are at least two years old. The furthest south that a ringed bird from the valley has been recorded is one from Walthamstow Wetlands which was found in Spain on its way down to Africa: Southern Colour Ringing Group - Common Tern SR89361
Little Egret and Grey Heron
Grey Heron have nested in the valley for many years. In the 1950’s the Walthamstow Reservoirs colony numbered around 100 pairs and was one of the most famous Grey Heron colonies in the UK! Whilst the Walthamstow colony has declined, numbers in the wider valley have remained stable at around 100 pairs albeit at changing locations. Ringers monitor a colony on an island at Glen Faba. Each year the ringers count the nests and ring a sample of chicks. In 2012 the first pairs of Little Egret, first recorded as breeding in the UK in Dorset in 1996, started to breed in the valley and a project to colour ring both species was started. Whilst there has been very little information received back on the Grey Heron colony the colour rings have provided an insight into their local movements and survival data.
However, the information provided from the Little Egret ringing is much more interesting showing that chicks from the colony disperse far and wide with one making it to Tenerife Southern Colour Ringing Group - Little Egret GV77568
In 2025, the colony at Glen Faba began to shift onto a neighbouring island, with nest distribution split roughly equally between the original island and the new site. Similar movements have been recorded many times in the past, suggesting that the colony periodically relocates for reasons that are not yet fully understood. Food availability is unlikely to be the main driver, as the birds are moving only a short distance. Other possible factors may include the age and condition of the nesting trees, changes in colony structure, or disturbance.In 2025, the colony at Glen Faba began to shift onto a neighbouring island, with nest distribution split roughly equally between the original island and the new site. Similar movements have been recorded many times in the past, suggesting that the colony periodically relocates for reasons that are not yet fully understood. Food availability is unlikely to be the main driver, as the birds are moving only a short distance. Other possible factors may include the age and condition of the nesting trees, changes in colony structure, or disturbance.
Barn Owls
Barn Owls were known to breed at the Park’s Holyfield Hall Farm. To encourage their dispersal across suitable habitat the Authority installed a number of Barn Owl boxes around the park. Success varies year on year and is dependent on the weather and availability of their prey such as mice, voles and shrews . In bad years we may not have any, but in good years large broods of up to six chicks have been recorded in the valley. In 2026 two broods were ringed from boxes in the Park, with three chicks at Ryegate Farm and four chicks in the box at Holyfield Hall Farm. Outside of the nesting season the boxes are used as day roosts.
Red Kites
By the late 19th Century the once widespread Red Kite were extinct from England. Following a successful reintroduction in the 1990’s they have spread, expanding their range and numbers, becoming a common site around the Park. Although still a rare breeding bird, requiring a Schedule 1 licence to disturb or ring them, they are in fact very tolerant of humans and will nest quite close to people. In 2026 a pair nested near one of our campsites. The two chicks were ringed and wing tagged – a wing tag is a lightweight plastic marker attached to the bird’s wing making them identifiable with binoculars or telescopes. If they are seen again we can track their movements and life history.
Together, these projects show how long-term bird ringing and targeted monitoring continue to inform conservation management across the Lee Valley. The results help the Authority and its partners understand population change, improve habitat provision and respond to emerging pressures demonstrating the value of sustained, site-based ornithological recording.
If you do see a bird with a colour ring or wing tag, please report it to the Southern Colour Ringing Group - Report a sighting or via the BTO website
By Paul Roper – Qualified bird ringer for 45 years and Head of Property & Funding Delivery, Lee Valley Regional Park Authority