Barn Owl breeding success

Barn Owl breeding success
© Ryan Greaves

By James Duncan

Woods Mill Learning and Engagement Officer

The ghostly silhouette of a barn owl (Tyto alba) has been a regular sight here at Woods Mill over the years, but worryingly they hadn't bred on the reserve since 2012. Last year the old nest box reached the end of its useful life and was replaced with a plush new one, situated at the edge of Hoe Wood, in the hope it would encourage them back. After consistent sightings of a hunting pair and upon hearing a riot of screeching from the box over several nights, favours were called in and the box was checked. 

We're more than delighted to announce that there were five chicks inside! They were carefully weighed, aged and fitted with ID rings, by licensed owl ringers Stuart and Jake. Two of the young were female, three male. They were very well developed, with some larger than the parent birds and having already shown signs of venturing outside the box. Most birds tend to incubate only when their clutch is complete, but barn owls incubate from when the first egg is laid. This is known as 'asynchronous' hatching and it results in a hatching egg every 2-3 days. This can of course mean there may be a difference in age of the youngest and oldest nestlings of around 10-15 days. This difference seemingly helps to reduce the peak in food demand, aiding the survival chances of the whole brood.

Barn owls2

The barn owl was until 2015 an amber listed species, showing significant declines in its UK range. The use of pesticides such as DDT, loss of suitable hunting habitat, harsh winters and collisions with traffic were all cited as possible reasons for their decline. However, there's been a recent upturn in numbers and the erection of nest boxes, amongst other conservation measures, has assisted them greatly. This is largely owing to barn owls not 'building' a nest. They tend to lay on an accumulation of last years' amalgamated nest debris - a compacted pile of their regurgitated pellets. Where there is none (in this case) the eggs may be laid directly onto pellets produced while roosting, or alternatively a nearby hard surface!

The fledging of six Woods Mill kestrels this year has shown the reserve to be a healthy habitat, alive with mammals. Rodent populations tend to be cyclical and raptor survival is directly tied in to their success. Short-tailed field vole usually determines almost half the barn owl diet, with common shrew and wood mouse making up more than a quarter. It's worth considering that each owl will typically require 3-4 prey items per night, with the same ideally required for each owlet. This equates to over 2000 prey items needed to feed both the adults and their offspring during the breeding season. They sure have their work cut out! This is made even more difficult considering their inability to hunt during unfavourable weather -  heavy rain or strong winds.

Barn owls3

If food is in good supply the owlets frequently overtake the weight of the adult birds by around 6 weeks old. Any premature deaths owing to food shortage will have occurred by 7 weeks and healthy owlets typically take around 10 weeks to fledge and become competent flyers. During the fledging period the young will regularly return to the nest box and roost together by day. Learning to hunt is an entirely instinctive process and amazingly they receive practically no 'training' from the parent birds. Many of the owlets will have captured their first prey item by 11 weeks and by week 12 they're receiving reduced amounts of prey from the adults. They will be venturing further and further from the nest site until around week 14, when 'dispersal' occurs - they leave to find their own home range. There is evidence to show that lingering fledglings are chased away by the parents, though conversely some are tolerated - for a while at least. The average dispersal is less than 10 miles, though it's an incredibly sad fact that many die during this period. As they leave Woods Mill they'll face a multitude of challenges. These include their hunting inexperience, the unfamiliarity of new landscapes during dispersal, the weather conditions during the shift from autumn to winter and their chances of encountering the man-made hazards that are part of our landscape. We certainly wish our five all the very best in their journey.   

Comments

  • 03 Aug 2018 13:58:00

    Most gratifying. Congratulations!

  • Maya Davis:

    03 Aug 2018 14:47:00

    Great news! Barn owls have had a horrible time this year, so five owlets raised to adulthood is wonderful. Here’s to continuing success next year

  • Ian Williams:

    04 Aug 2018 08:22:00

    Brilliant. Barn Owls were re-introduced to a barn in Faygate a some years ago now but eventually failed. They used to hunt in the field behind us and we used to see them quite often, and the male passing his “presents” to the female. The barn has since been converted to residential and the field will be part of the proposed 2,500 house North Horsham Development.

  • 09 Aug 2018 11:33:00

    Thank you for the comments, it is indeed such fantastic news! In an era where ‘barn conversions’ are rife and suitable nesting habitat is destroyed, it’s so very heartening to witness the results of a successful brood. Here’s to many more!

  • Carole Nicholson:

    30 Aug 2018 10:55:00

    Fabulous news, James – thanks for sharing!

  • June Eade:

    30 Aug 2018 12:27:00

    How very wonderful!

  • Pat Winter:

    30 Aug 2018 14:38:00

    What a marvellous story of barn owls so graphically described, from egg to heading out on their own. And great photos. Well done too, Woods Mill, with the kestrels.

  • Angela Colyer:

    30 Aug 2018 15:51:00

    An awe inspiring story. Terrific news on both the barn owls and the kestrels. Let us hope that they avoid all the hazards and make it through to next year.

  • diane salter:

    30 Aug 2018 18:48:00

    congratulations hope they do well

  • Jill Alexander:

    30 Aug 2018 20:21:00

    What chance of seeing the barn owls that your webpage mentions? I am disabled and probably need to use my power buggy.

  • Linda Howard:

    31 Aug 2018 09:25:00

    That’s Fantastic News! So maybe a Barn Owl Camera next year?
    Kestrel Cam was addictive – so maybe not – I’d never get any work done. Well done on attaining such a prolific, healthy, balanced Nature Reserve.

  • david phillips:

    31 Aug 2018 09:48:00

    Excellent News indeed . Well done to all concerned.
    Success also here nearer my home on Pevensey Levels.
    Any volunteers needed to erect new boxes in Sussex generally or assist with monitoring , ringing ? Am keen to be involved.

  • Malcolm Barber:

    31 Aug 2018 12:25:00

    This is very good news indeed. Such a beautiful creature too. Hopefully the numbers will continue to improve.

  • 04 Sep 2018 12:08:00

    Thank you to everybody who’s commented. We would love to be able to introduce ‘Barn Owl Cam’ next year, so watch this space!

    The Barn Owl Trust are always looking for more data on their distribution, so do please check their website for more info on volunteer work, including undertaking surveys and erecting nest-boxes.

  • tomnewell:

    08 Sep 2018 10:56:00

    happy to put up some nesting boxes on my stable in Compton. Advice welcome

  • 12 Sep 2018 09:28:00

    The Barn Owl Trust have some great info pages on owl nestbox location, design and erection –
    https://www.barnowltrust.org.uk/barn-owl-nestbox/

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