Barn owl numbers are under threat because of the recent extreme weather.
According to experts, who have been monitoring 73 sites in Devon and Cornwall, the birds have had their worst breeding season in decades following 2012's washout summer and this year's cold spring.
Nesting took place in just one in eight sites (12%), compared to nesting on average in half the places (51%) checked last year, the Devon-based Barn Owl Trust said.
Nests where pairs have managed to survive and breed had an average of just two owlets in the nest rather than the four or five needed for populations to recover, the organisation said. And a survey conducted every 10 years in Devon, which will examine 1,234 sites this year, has found that of 276 sites checked so far, barn owls were nesting in just seven, with only four containing young.
It is a similar picture across the country, according to figures from independent barn owl groups. Shropshire Barn Owl Group normally expects around 36 nests from 120 sites, but this year has only found four. In West Sussex only five of 90 sites have nests, the normal figure is up to 55.
Experts say a run of extreme weather in recent years, with bitterly cold winters in 2009/2010 and 2010/2011 and the wet summers in 2010 and 2011 have hit numbers of the bird.
The washout summer in 2012 dashed hopes sparked by the warm, dry spring of a good breeding season and the "final blow" was March this year, when bitterly cold conditions extended the winter and killed many birds. Trust spokesman David Ramsden said the figures showed barn owls could not cope with extreme weather. and "we seem to have had nothing but extremes the last few years."
He said: "In 2012 our hopes were high. Fantastic summer weather in March 2012 meant that the owls started breeding earlier and by late May we were finding nests with as many as seven well-grown owlets.
"Then in June it all went horribly wrong. The rain started and just didn't stop. This prevented the adults hunting and many young birds starved. In some cases we found entire broods of beautiful owlets dead in the nest."
The weather has continued to have an impact into this year, with the icy, snowy conditions in March, he said.
"Barn owl mortality usually peaks in February and then things improve, but in March this year mortality just kept increasing and by the end of the month huge numbers were dead," he said.
The impacts of the weather come on top of long-term declines for barn owls, with estimates of 70% falls in numbers between the 1930s and 1980s due to a number of factors – more intensive farming and loss of hedgerows, meadows and old farm buildings.
The Barn Owl Trust warned that if this year was anything to go by, the barn owl was now even more scarce.
