Rare Blue-Tailed Damselfly Returns to a Rebuilt Chalk River Near Hertford

An endangered insect from one of the oldest flying lineages has turned up beside a chalk river that was put back on its original course. The scarce blue-tailed damselfly, described by BBC News as one of the world's earliest flying insect species, was recorded along the River Ash near Hertford, in wetlands created by a restoration project.

The sighting arrives at a worrying moment for these insects. A new national assessment has moved the species into a higher category of risk, which makes any sign that it can use restored habitat notable to conservationists.

The restoration and the sighting by the numbers

• 4.3-mile (7km): the length of the River Ash stretch at the Easneye Estate that was returned to its original course last year, according to BBC News.
• Two: the number of monitoring sites, located close together, where the scarce blue-tailed damselfly was recorded in late summer.
• Eight: the number of dragonfly and damselfly species now classed as endangered in the British Dragonfly Society's Red List review. That is twice the number found in the previous assessment in 2008.
• About 260: the number of chalk rivers in the world. The River Ash is one of them.

What changed on the river

The Herts and Middlesex Wildlife Trust said the restoration included creating new gravel beds in the river. The trust reported that brown trout were already spawning on them.

Monitoring carried out before and after the restoration also found an increase in river invertebrates, including mayflies and stoneflies, the trust said, according to BBC News. The damselfly was recorded in the same area during late summer.

Why it matters for a species under pressure

The British Dragonfly Society's review reclassified the scarce blue-tailed damselfly from Near Threatened to Endangered. The same assessment highlighted growing concern about the future of some other species of dragonflies and damselflies in Britain.

Against that backdrop, the wildlife trust said that for species facing increasing pressure, creating and restoring suitable habitats is vital to reversing declines. The River Ash sighting is a single record from two close-together sites, so it does not show that the species is recovering. It does show that the insect has been found at a spot where the river was recently reshaped.

Sarah Perry, rivers recovery manager at the trust, said natural rivers, connected floodplains and healthy wetlands support biodiversity by giving wildlife places to feed and breed. She added that these landscapes help water move through the countryside and can contribute to resilience against both flooding and drought. In her view, the damselfly sightings offer a hopeful example of what such efforts can achieve.

For ordinary readers, the practical point is that restoring a river can bring benefits beyond the water itself. The trust ties healthier rivers, floodplains and wetlands to places where wildlife can feed and breed, and to the way water moves through the landscape during both floods and droughts.

What the early results suggest

The damselfly is one part of a wider picture. Before-and-after monitoring found more river invertebrates, trout were using the new gravel beds to spawn, and a species whose status has just worsened was recorded at the site. The trust presents the sightings as a hopeful example rather than as proof that the species has recovered. The damselfly was recorded at two monitoring sites that sit close together, and the sighting came in late summer.

The trust's message is that creating and restoring suitable habitats is vital to reversing declines, especially for species facing increasing pressure. The River Ash project, with its restored course and its new gravel beds, is being held up as one example of that approach in action.

Around Prague, based on reporting by BBC News