Colin Shawyer's Barn Owl forecast 2014
Widely recognised for his work on the study and conservation of owls and raptors, professional ecologist Colin Shawyer has collaborated with the BTO on projects such as Project Barn Owl (1995-1997) and the Barn Owl Monitoring Programme (2000-2009). As founder and co-ordinator of the Barn Owl Conservation Network (BOCN), Colin is in regular contact with Barn Owl experts across the country and oversees the annual monitoring of over 3,000 Barn Owl nest sites.
Back to breeding in 2014
In 2013, the number of Barn Owls encountered breeding at nest sites was down about 80% on previous years. This season, however, I am forecasting high vole abundance throughout much of mainland Britain and I anticipate that a good proportion of Barn Owl pairs will attempt to nest.
Site occupancy may remain lower in parts of the UK where there has been prolonged surface water. Experience has shown that in these situations, adults will move to the edges of their normal winter range and up to 5km from traditional nesting sites. At these refuge areas, some birds will then stay and attempt to breed if nest sites are available and pair bonds remains intact, though pairs have also been recorded returning to their traditional nest sites after two or three years, once surface water has receded and vole populations have increased.
Best times to visit boxes
In stark contrast to 2013, some Barn Owls have already begun laying this year—a few even started in the last two weeks of March, which is especially early—and for about two-thirds of established pairs I expect that the first egg date will be during the first week of April and clutches will be complete by the second and third weeks. Late April, therefore, should be a good time for visits to record full clutch sizes and the best time to ring broods is likely to be Mid-June to mid-July.
However, first-year birds from the exceptionally late broods that some pairs had in 2013 will be unlikely to breed until mid-May or June, after they reach sexual maturity. Consequently, there may be two distinct waves of breeding in 2014: the first in early April and the second during late May or June.
Remember to be cautious about nest visits just prior to and during egg-laying, since this can sometimes cause Barn Owls to leave the chosen nest site and seek an alternative one nearby, particularly if the birds are new to the nest site.
Brood sizes are likely to be higher this year and for pairs that begin their first clutches before about 21 April, double-brooding will be on the cards, although not all pairs will attempt this. Perhaps we will see polygyny occurring this year as we have seen before when prey has been abundant.
One possible advantage of early breeding and high prey abundance this year is that Barn Owls will be better able to defend their nest sites against jackdaws, which themselves do not normally complete nest building until later in April.
Record ringing totals
Currently in the UK, BOCN and BTO fieldworkers could be ringing as many as one-third of Barn Owl fledglings in a given year. The proportion is difficult to estimate, but a study I recently undertook in an area of eastern England where there had been a large amount of Barn Owl conservation and research found that 50% of Barn Owls of all ages found dead in the area had been ringed. If 85% of c.9000 pairs breed successfully in the UK in 2014, and they have an average of 3.5 chicks per nest, then roughly 27,000 chicks will fledge. In comparison, 10,000 Barn Owl chicks were ringed in the UK in 2007, the current annual record.
A conservation success story
Many of the local and regional Barn Owl populations the BOCN and others have been working to restore over the past 25 years are becoming sufficiently resilient to withstand the damaging effects of short-term climatic extremes and levels of unnatural mortality previously considered insurmountable from a conservation standpoint. Conservation work will, however, remain essential for the Barn Owl, a species which is now heavily reliant on the maintenance, monitoring and continued replacement of artificial nest sites. As I have said over the last few years, in recognition of its dependence on artificial nest sites, ought we to consider renaming this species the Box Owl Tyto alba – a change from ‘Scritch Owl’ and ‘Barn Owl’, both names that were first used in the 17th century?
Have a great year and if you need help or any advice I am usually on the end of my mobile 07774 899344 or on email colinshawyer [at] aol.com.
28 March 2014
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