At least the birds think British summers are Mediterranean

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Published by on July 11, 2012 courtesy of RSPB

Recent British summers may have been a turn-off for human sun worshippers, but some birds seem to have a different view. The firecrest – one of the UK’s smallest birds – is increasingly nesting in Britain, from further south in Europe.

However, although the latest report from the Rare Breeding Birds Panel (RBBP), shows the firecrest is increasing rapidly, it paints a bleak picture for the Dartford warbler, which appears to have declined substantially in the last few years, because of the harsh winters leading up to 2010.

The tiny firecrest – four together would weigh less than one ounce – first colonised the UK half a century ago, when the first nest was found in Hampshire in 1962.

Since then the population has risen, and the latest report from the Rare Breeding Birds Panel suggests there may be over 1,000 pairs nesting in Britain, primarily in southern England. Before nesting in Britain, the firecrest spread gradually northwards in Europe from its stronghold around the Mediterranean.

Firecrest © Nick Ransdale, from the surfbirds galleries.

In 2010 – the latest year to be covered by the RBBP report – there were reports of at least 800 pairs of this tiny woodland bird. But, because of its diminutive size, elusive tree-top habits – and its similarity to the more familiar goldcrest – experts believe there could be well in excess of 1,000 pairs now nesting in the UK, all in England and Wales.

Struggling

But the RBBP report shows that the robin-sized Dartford warbler, also more common further south in Europe, is showing signs of struggling in the UK because of the recent harsher winters. The report shows that in some parts of its range, the Dartford warbler has suffered particularly badly. For example, in 2004, there were almost 1000 pairs in the Thames Basin and Wealden Heaths, but in 2010 there were reports of just 50 pairs across these areas of Berkshire, Hampshire, Surrey and Sussex.

Thankfully, however, those tiny outlying populations in counties like Norfolk and Staffordshire – away from the larger strongholds on the heathlands of southern England – seem to have survived, at least helping to preserve the bird’s range in England and Wales.

Mark Holling, secretary of the RBBP, said: ‘In the last 50 years there have been a number of species which have nested for the first time in Britain. Some, like the purple heron, have only nested once but others, like the little egret and firecrest, have gone to become established and relatively widespread nesting birds.

‘These shifts shown by some nesting birds fit the pattern of climate change with species moving from further south in Europe to colonise the UK.’

Mark Eaton, RSPB scientist and RBBP chair, said: ‘Perhaps the firecrest’s success in Britain shouldn’t come as a surprise. The warmer summers we’ve seen in recent decades favour this bird, and during the winter it leaves its nesting sites to winter along the coast of south-west England or on continental Europe, so avoiding the worst of our winter weather.

‘In contrast, the Dartford warbler stays put on the breeding grounds all year-round. It is believed that warmer summers and, until recently, milder winters have allowed them to spread further north in England. But the run of harsh winters look like they are taking their toll on this bird.’

Mark Eaton added: ‘Sadly, the Dartford warbler is currently a casualty of the combined double whammy of weather and climate: a changing climate in the south of its range is affecting it, with rapid declines in its Spanish and Portuguese heartlands. While in the north of its range, where the summer climate is improving, it is being badly affected by harsh wintry weather.’

Harsh winters

The RSPB has been working to help the Dartford warbler since the harsh winter of 1962/1963 when there were only a handful of these birds left in Britain. Extensive habitat management to regenerate and improve heathland had enabled a vital recovery of the Dartford warbler in England, but the impacts of further harsh winters are in danger of knocking the population back at some key sites.

Other notable events featured in the 2010 report include:
• The golden oriole – a striking thrush-sized yellow-and-black bird – was not confirmed nesting in the UK during 2010; the first potentially blank year since 1973
• The purple heron and pink-footed goose were both recorded as nesting for the first time in the UK in 2010
• Another coloniser from Europe, the Mediterranean gull, also reached 1,000 pairs in the UK, but its numbers may have dropped again, following two poor breeding seasons at some sites.

The Rare Breeding Birds Panel report is published in the latest edition of the journal British Birds.

Notes:
1) The Rare Breeding Birds Panel collects breeding data on the rarer species of birds breeding in the United Kingdom. In particular, its records allow the production of annual totals of breeding pairs for each species on its list. The Rare Breeding Birds Panel was formed in 1972 by representatives of the Royal Society for the Protection of Birds, the British Trust for Ornithology, The Nature Conservancy Council and British Birds. The present Panel is made up of representatives of the Joint Nature Conservation Committee, RSPB, BTO, three independent members, and a Secretary.

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