A long-running study  into the life of the pied-flycatcher is showing worrying signs of the effects of climate change, as Martin Hesp reports

THE old joke about newspapers used to go: what's black and white and read all over? Now ornithologists are asking: what's black and white and surveyed over a very long period of time?

The answer is the pied flycatcher, which has been the subject of one of the longest continuous surveys of its kind on record. The monitoring programme in question is based in woodland near Okehampton, where these remarkable little birds have been closely scrutinised for 35 years.

In that time, thousands of pied-flycatchers visiting north Dartmoor have been ringed, their movements followed and their life-spans calculated.

The black and white birds, slightly smaller than a sparrow, fly from Africa each spring to nest in the damp warm woodlands of Britain's west coasts.

The trouble is, the woodlands are not always quite so warm and are sometimes rather too damp. At least that's one of the findings of the survey, which has discovered that, in recent years, the numbers of fledging pied-flycatchers making it through to adulthood are seriously down.

"We've had a spate of wet and cold springs and the pied-flycatcher productivity is pretty bad," says Naomi Scuffil, who is the Dartmoor National Park Authority ecologist now in charge of the survey.

"Quite a few broods have been fledging earlier before they are quite ready because parents haven't been able to feed them in the nests. If they hop out earlier and help themselves they stand a better chance, but the rain and cold can hit them."

Naomi explained how the long-lived survey had begun: "The scheme was originally monitored by British Trust for Ornithology (BTO) volunteer Gordon Vaughn. Since his death in 2006, Dartmoor National Park Authority has been continuing his work, which is one of the longest-running datasets on pied-flycatchers in the UK.

"It has proven to be a valuable species to research, enabling studies of mating, breeding and productivity," she added. "In the longer-term, information gathered on return dates, laying dates, and breeding success can be evaluated and calculated, providing valuable information for conservation organisations and enabling decisions to be made on how to best conserve Britain's wildlife in the face of a changing climate."

Monitoring nest boxes occurs in late May and early June when breeding starts in earnest. Weekly visits are carried out and the progress of each breeding pair followed. In addition, the adults and broods are ringed as part of the BTO's bird-ringing scheme.

Naomi, who is in regular contact with other pied-flycatcher monitoring schemes in the region, told the WMN that, although these summer visitors are not yet on the official endangered list, they could soon be if recent performance figures continued.

"Surviving their first year is the tricky bit – if they do, we find they can come back for four or five years," she said. "And they are slowly arriving earlier, maybe because of the spate of wet and cold springs.

"One theory is that the timing of greatest abundance of their prey for the chicks, mainly caterpillars, is shifting forward due to warmer winters and early springs, so that there is not enough food around at the right time of year for the pied-flycatchers."