Sunday, 12 August 2012

Get the habitat right...

It was interesting to see in the August edition of British Birds magazine the report that a pair of Black-winged Stilts had attempted to breed this year in Somerset, news that had previously passed us by.  Of course, Black-winged Stilts are birds that we see every day around Tavira but breeding records in the UK have been very few.  Peter recalls seeing two juvenile birds at Belvide Reservoir in September 1987 that were almost certainly from a successful nest that year in Norfolk and the record books show that way back in 1945, three pairs laid eggs in Nottinghamshire and produced three young.  Sadly this year’s nest was deserted within just a few days of being found, reportedly falling victim to the weather.

Somerset seems to be the place these days for rare breeding birds to try their luck!  After an unsuccessful attempt in 2010, two pairs of Great White Egrets have managed this year to raise young there and it was also in Somerset that Cattle Egrets bred for the first time in Britain in 2008 and where there was the second proved breeding of Little Bitterns in 2010.

The numbers of Great White Egrets occurring in Britain has been increasing steadily in recent years at the same time as the species has been expanding its range elsewhere in Europe.  Breeding also took place for the first time in Germany this year while in Poland, where the first nest was found in 1997, there were reported to be more than 140 nests in 2011.  That the species should also begin colonising Britain is no surprise.  Interestingly, one of the Somerset breeding birds had been colour-ringed in France in 2009.

It was probably only a matter of time before Cattle Egrets also nested in Britain and perhaps surprising that there have been no reports of any further attempts since 2008.  The Cattle Egret has undergone one of the most rapid and wide reaching natural expansions of any bird species and seems able to flourish in the company of domesticated livestock as easily as it originally did with the herds of wild grazing mammals of Africa.  In the twentieth century they expanded to South Africa, Australasia, South America and North America as well as northwards within Europe.   They are birds that we see every day from our window in Tavira as they fly to and from their roost sites. 

The case of Little Bitterns is slightly different.  These are skulking birds that can easily be overlooked and although there is only one record of proved breeding in Britain prior to 2010 (in Yorkshire in 1984), they were strongly suspected of breeding in East Anglia in the nineteenth century and also in southern England in 1947.  Pairs are known to have summered in Surrey (1956), Somerset (1958), Huntingdonshire (1960) and possibly elsewhere.

To be fair, there have been similar breeding successes elsewhere than in Somerset.  After a pair of Purple Herons failed in their attempt to raise young in Suffolk in 2007, there was success for a pair in 2010 at the RSPB reserve at Dungeness in Kent.  Again, there has been a steady increase in the numbers of this species occurring in Britain since the 1970s, most of them turning up in the south east, suggesting that they originate from the Dutch population.

In one or two reports that we have seen of these events, it has been suggested that they have been brought about by climate change, presumably a change that is particularly affecting Somerset!  What is certain is that in Somerset the Avalon Marshes (Ham Wall RSPB reserve and Shapwick Heath National Nature Reserve) now represent one of the most extensive wetlands in Europe and provide just the right habitat for these colonising birds.

An important feature of the Avalon Marshes project has been the creation of reedbeds to encourage Eurasian Bitterns to breed and two nests at Ham Wall in 2008 were the first in Somerset for 40 years.  This has been just a part of a major programme of reedbed restoration and creation over a period of 15 years or more which has brought about a significant increase in the British breeding population of Bitterns.  Once widespread and numerous, Bitterns were in danger of being lost as a breeding bird in Britain mainly as a result of habitat degradation.  Now, as well as in Somerset, they can be heard booming in more than 50 sites around the country with definite breeding in Norfolk, Suffolk, Cambridgeshire, Kent and Yorkshire.

So far the return of Bitterns is a remarkable success story and a demonstration of what targeted conservation action can achieve.  It has had the added benefit of providing conditions suitable not only for colonisers like the Great White Egrets but also for Marsh Harriers, Bearded Tits, Reed Warblers and Sedge Warblers, not to mention mammals, amphibians, fish and a host of insects.

Get the habitat right and the birds will do the rest – it’s simple really!

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