Welsh Harp Reservoir to see common tern nesting rafts

The silvery grey and white common tern, whose long tails gave them the nickname ‘sea-swallows’, have been in “significant decline” over recent years.

After numbers dwindled to just two chicks, the Canal & River Trust hopes to build new breeding rafts for the birds at the Welsh Harp Reservoir in north west London to support the threatened species.

It involves 14 new tern rafts, providing island habitats to support the birds at the reservoir, which is protected as a Site of Special Scientific Interest (SSSI) for the rich diversity of wildlife found on site, including water birds and 16 protected plant species.

The Welsh Harp reservoir was left drained for months since the end of last year for maintenance work and also to clear tonnes of litter.

A sign at Welsh Harp Reservoir (Image: Joseph Reaidi)

Now the reservoir is nearly fully restored to its normal water level and other wildlife is returning.

According to the trust, there were over 40 breeding pairs of terns at the nature spot in the past, but in 2023 this dropped to only two chicks.

Terns arrive in the UK in April and then return to western and southern Africa in September.

The drained Welsh Harp Reservoir in April, 2024 (Image: Joseph Reaidi)

The birds have a "graceful, floating flight" and frequently hover over water before plunging down for fish, according to the RSPB.

Ben McMillan, ecologist for the Canal & River Trust’s London & South East, said: “As part of a series of environmental improvements at the reservoir, and with the support of the Welsh Harp Conservation Group, we’re installing 14 new island habitats for common terns, one of the species of water bird that lives there and cited within the reservoir’s SSSI designation.

“The island habitats we’re installing will provide a safe space from flooding and predators for the birds, hopefully improving their breeding success. The islands are made of durable recycled plastic with a layer of shingle to imitate the terns' natural beach nesting habitat.”

Welsh Harp Reservoir during its clean-up operation (Image: Canal and River Trust)

Steve Leeke, of the Welsh Harp Conservation Group, added: “We first installed wooden tern rafts here in the 1980s and at their peak at the turn of the century, they provided island habitats for an amazing 44 nesting pairs.

“Sadly the rafts have deteriorated over time and are no longer a viable nesting site. As a result, the number of visiting terns has declined, with last year only four pairs attempting to nest and producing just two chicks.

“These new breeding rafts provided by the Canal & River Trust will support this threatened species and are a welcome step in enhancing the biodiversity of the Welsh Harp.”