NRS suggests delayed breeding in 2013

Delayed vegetation growth in 2013 left people waiting for blooms of bluebells, but migrant Reed Warblers also had to wait for their reed bed nesting habitat to become suitable.
Photos by Rob Fuller and John Bowers

Many of the obvious signs of spring were two to three weeks late this year, no doubt thanks to an exceptionally cold March and wintery conditions that continued to the end of April. On 1st May, trees were bare, Blackthorn blossom was nowhere to be seen and Bluebell woods were distinctly lacking in colour. But what about nesting birds? According to anecdotal reports from participants in the BTO's Nest Record Scheme, a variety of species appear to have been similarly delayed this year.

Early April checks of Blue and Great Tit boxes, timed to coincide with when the birds generally start laying, revealed little evidence of nest-building activity, let alone laying. Richard, from Cambridgeshire, remarked, 'out of c.150 boxes, we had our first Blue Tit egg on Sunday 21st April, and a Great Tit egg on Monday, but most have little or nothing'. By the second week of May, however, there were plenty of reports of clutches being incubated, although box occupancy appeared to be lower than usual. In the first week of June, while monitoring the last few broods still to fledge, Roger in Dorset remarked that more chicks than usual had died semi-grown, a statement echoed by recorders in Cambridgeshire, Cornwall and elsewhere, and suggestive of low caterpillar abundance.

Larger resident species also appear to have been delayed. In June, reports from Buckinghamshire, Hertfordshire, Cumbria and Cambridgeshire all concurred that Barn Owl boxes were mostly empty, with the notable exception of a Barn Owl brood in Cambridgeshire that had been laid in early March. By 7th July, John, a recorder from Norfolk, reported that occupancy was still very low in his 35 boxes: he'd counted two clutches and two young broods.

Short-distance migrant passerines arrived in the country relatively late this year and subsequently nest recorders reported species such as Blackcap getting off to a slow start by mid-April. Many long-distance migrants, including Reed Warbler, started to arrive at their usual time towards the end of April, but they too appeared to delay breeding. At a regular Reed Warbler study site in Norfolk, birds were at least two weeks late laying, mainly because they had had to wait for the reeds to grow further. Indeed, reed growth was so retarded that many pairs were forced to use alternatives such as willows and nettles.

Come Autumn, when nest recorders begin sending in their data for the season, a more accurate picture of both timing of breeding and productivity will be published in the annual preliminary report on the breeding season.

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