Barn owl nest recorder predicts another good breeding season for 2015
- Credit: NEIL CALBRADE/British Trust for
The number of malnourished dead barn owls discovered on the ground during the cold spring of 2013 brought alarming predictions that the bird's population was in crisis.
And fears were compounded later that summer when barn owl recorders found traditional barn owl territories unoccupied.
However, the vagaries of the British climate then brought a record mild winter and spring - and that was the recipe for a record year for barn owls too, according to survey organisers for the British Trust for Ornithology.
Carl Barimore, nest records scheme organiser for the Thetford-based charity, said: 'Across the UK licensed BTO volunteers monitored 2,860 barn owl nesting attempts in 2014 compared to just 800 in 2013.'
As well as birds being back on breeding territories in abundance, analysis of the data showed productivity in 2014 - measured as the number of fledglings per breeding attempt - had also been at an all-time high.
Shedding light on the dramatic contrast in barn owl fortunes from one year to the next, Mr Barimore said: 'The start of 2013 saw a very cold and wet winter and exceptionally cold April and May.
'It meant adults were not in good condition when spring eventually arrived and that led to smaller clutch sizes and many adults not breeding at all.
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'Recorders found themselves checking empty boxes and wondering whether there would be a breeding season at all.'
He said probably adding to the barn owl's predicament was evidence that the harsh weather at the start of the year had led to a dramatic decline in the population of voles, the bird's primary food source.
'Observers were finding very few prey items in nest boxes,' he said.
Last year, by contrast, had seen a dramatic revival in the vole population in the wake of mild winter and spring weather - 'nest recorders saw a big increase in vole numbers which can follow a cycle of boom and bust' - and barn owl nesting boxes were consequently brought back into use like never before.
While the statistics are obviously good news, and Mr Barimore is predicting another good breeding season in 2015, he said it was important to put the data into context.
He said: 'It is a well-know feature of barn owl populations that they can undergo apparently large but short-term fluctuations in both nest-site occupancy and overall productivity - it is just that the last two seasons have been particularly marked examples.'
He added that the number of empty nest boxes in the summer of 2013 had also, to some degree, been deceptive.
'The decline in the population was not as dramatic as it might have looked from the empty boxes. It was just that many adults did not breed due to the climate and shortage of food,' he said.
Mr Barimore said it was difficult to assess the longer term picture for barn owl populations as specific surveys were difficult, due to the bird's nocturnal nature, and were only carried out every 10 years.
However, he said: 'The impression of most experts is that populations are recovering after a decline throughout most of the 20th century.
'The first barn owl survey in 1933 recorded 13,000 pairs in England and Wales but that had declined to the point where the Hawk and Owl Trust recorded just 4,500 pairs in 1982.
'Most people think barn owls across the country are now back up to 6,000 pairs.'
He said the key factor in the decline had been habitat loss and the recovery had been borne out of recognition of that fact.
A lot of good work had been carried out by farmers and landowners to restore the owl's rough grass habitat, for example along field margins.
'There has also been work to supplement nesting opportunities by putting up thousands of nesting boxes,' he added.
'They can be on the side of a barn or on a pole in the middle of a field. The owls don't seem to mind.'
Mr Barimore said East Anglia was one of the UK strongholds of the barn owl, offering ample opportunities to see the graceful bird.
Anywhere with areas of rough grassland was a possible place to find them.
'The best times to catch sight of one are at dawn or dusk when they are hunting, but it is possible to see them later in the day as well,' he said.
The BTO relies on volunteers to carry out bird surveys. Anyone interested in taking part is invited to contact the charity via its website www.bto.org
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