Acid-free rivers herald renaissance of Wales’ Dippers

Bird Notes columnist Julian Hughes of RSPB Conwy reveals what birds have been spotted in the past week and where to go birding in the coming days

 
ByAndrew Forgrave
20:50, 24 APR 2017

National Grid’s news last Friday that Britain ran without coal for the first day since before the Industrial Revolution is a landmark in tackling climate change – and good news in the hills.

If you were around in the 1980s, you might remember “acid rain”, a subject that is rarely mentioned now.

Sulphur and nitrogen oxides from coal-burning power stations mixed with water vapour and fell as acid rain, the effect greatest in the hills with its heavier rainfall.

The Dipper was the canary in the upland coalmine (an ironic analogy, I know). Dippers eat aquatic insects – such as Mayflies – that are sensitive to acid levels and were wiped out from the many acidic Welsh streams.

A long-running study in Wales, led by Cardiff University, shows that Mayflies have recovered in 60% of streams monitored; good news for birds such as Dipper and Grey Wagtail.

Dippers can now be found on many of North Wales’ fast-flowing streams, nesting in crevices under bridges. The first fledglings were out of the nest last week in the Conwy Valley .



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Birds exposed to 'hidden pollutants' in south Wales valleys

Birds which have returned to the former industrial valleys of south Wales are being exposed to extremely high levels of hidden pollutants, experts warn.

Tests on eggs of dipper birds found chemicals used as flame retardants in furniture and motor vehicles.

The birds have fed on local rivers in growing numbers since heavy industries such as coal mining declined.

Natural Resources Wales says water quality has dramatically improved in the last 30 years.

Prof Steve Ormerod from Cardiff University's school of biosciences said PBDE and PCB compounds they found may be potentially hazardous to the birds, but the impact is not yet fully known.

"It's a paradox that on one hand dippers are progressively colonising rivers that used to be grossly polluted and they are being exposed to new, novel pollutants whose impact we don't fully understand," he said.

Sign of cleanliness

The tests found that urban rivers in south Wales contain some pollutants at levels, on average, over four times greater than in adjacent rural rivers.

"What we're learning here is that urban areas have increased concentrations," he added.

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