Barn Owl Project Report 2016

b-owl-head 2016 BARN OWL PROJECT REPORT

2016 has been an interesting year for the project with a mix of mysteries, disappointments, surprises and a great deal of enjoyment.

We decided to review our ever increasing database and move some sites to the inactive category, either because they have become defunct or situations have changed such they are not now likely to be used. They remain on the database and will be resurrected if any activity is reported in the vicinity. At the same time we have added new sites where we have erected boxes. We also discovered 6 boxes erected by property owners who have been kind enough to let us include them in our monitoring project.

A few statistics for 2016

  • 165 sites were checked at least once, either by visit or by phone call to the site owner
  • 21 sites were found to be occupied – a good result as it is normally expected that about 10% will be occupied.
  • 18 of those were occupied by a pair & 3 by single birds
  • 4 of the pairs failed to breed: 1 laid 5 eggs but male went missing – presume died: 1 male was found with badly broken wing and had to be put down after examination by a vet: 1 was a pair in residence which had not bred when we checked in July – It is possible but unlikely that may have bred later: 1 laid 2 eggs but did not hatch.
  • 14 did breed
  • 31 chicks were counted (average 2.21 chicks per breeding site)

Previous years

The history of breeding pairs found in the previous 10 years was:

2007   10        2008   9          2009   11          2010   9          2011   13b-owl_in-flight2a

2012  20         2013   3          2014   12          2015   18         2016   14

14 in 2016 makes it the 3rd best year on record for the number of breeding pairs found (years prior to 2007 were all lower). There has been a continuing increase in the number of nest boxes in place, since the project began in 1994. which has helped swell the population. Numbers vary naturally from year to year depending on breeding conditions (weather, availability of prey and other factors). I have not shown comparative figures for the number of chicks counted in previous years as this is highly dependent on the timing nest inspections – the later we do this the more young chicks will have died especially in years of food shortage.

Late breeding

There has been a greater than normal proportion of breeding failure this year and later laying dates. The extreme example was a pair which still had not laid when we inspected on 21st June. On 12.8 we found 4 newly hatched chicks – so the eggs must have been laid around mid July – so some 10 weeks later than would have been expected. Probable reasons for the lateness and failure rate are:b-owlchick

  1. October 2015– mid January 2016 was a very wet period and this would have reduced the availability of prey.
  2. In turn that is likely to have increased the death rate of mature birds. (Barn owls only live about 3 or 4 years anyway in the wild).
  3. 2015 was an exceptional breeding year with lots of chicks hatching. Those which survived the winter would have taken the place of mature birds that died or formed brand new pairs.
  4. Birds breeding in their first year have a higher failure rate due to their inexperience.
  5. Egg production by the females takes up a lot of energy and so she needs to increase her weight to 385 grams before egg production begins. The shortage of food in the wet winter and spring would have restricted growth so that some likely did not reach the full weight until later than normal.

Rescue of a lost Juvenile Barn owl

The entrance to the nest box at one site is incorporated at the top of a gable end wall overlooking fields. When we first inspected the box this year, on 18th July, we found a female apparently on three eggs. Great! We revisited 7 weeks later on 6th September expecting to count the chicks but much to our surprise the box was empty, No eggs, no chicks and no adults. The chicks could not have flown as they do not start to make exploratory forays until about 9 weeks old and even at that age they stay close to the nest. A mystery!

Next day I received a phone call from the site owner to say that a Barn owl was sat on the sill of the window immediately below the nest entrance, so we rushed out to it, As we put up the ladder thejuvenile-b-owl owl dropped to the ground amongst shrubs but after a search and a brief chase along the ground we managed to capture it. We took it to the local vet to help examine it. There appeared to be no bones broken, it did not appear to be in pain and was not emaciated. So next day we returned it to the nest which it entered very eagerly. Over the next week we had a couple of dusk watches from a distance and were delighted to see both adults and 3 juveniles all playing around the property while being fed by the parents.

But why had the nest been empty on 6th September? Conclusion: The eggs found on 18th July must have already hatched but sitting in the debris on the floor of the box they appeared whole. Also we found that the box had moved over the years and that left enough of a gap for the chicks to be enjoying, out of sight, the freedom of the whole attic! Over the winter we need to discuss with the owners what corrective action is best.

Working with other organisations

Cam Valley Wildlife Group has always been keen to work with other like minded organisations. As far as the Barn owl project is concerned we have worked in liaison with The Hawk & Owl Trust for 22 years now since. Our own area overlaps with their Bath Group and Mendip Group areas both of which are large. They have been happy for us to take on the work so they have more time to concentrate on the remainder of their areas. Each year we provide details of our survey results to them.

Since 2012 we have been helping with the Somerset Wildlife Trust project to put up a new Barn owl box up in each of the 335 parishes in their area. We were pleased to help with the 15 parishes which lie in our area, finding suitable sites, erecting the boxes and now monitoring them as part of our project.

This year we formed a new alliance with well known Secret World Wildlife Rescue located at Highbridge in Somerset. They contacted me about 4 Barn owl chicks to see if we could find suitable release sites for them when they were old enough. A lorry driver had picked up bales of hay from a farm but when he reached his destination he heard chirping and discovered 4 just hatched pink and helpless chicks in the bales. He quickly took them to Secret World. Unfortunately the smallest died but the other 3 developed well under their care. A 4th chick from a different site was brought in. It was about the same age as the other 3 and so they were able to integrate it with them. We soon found a very suitable site at a farm with a very helpful farmer where we had a nest box in which Barn owls had nested in the past but not lately.

owlholdingcageA 5th Barn owl was then taken in at Secret World. This was older than the others so another release site was quickly found. At both sites all the owner families were extremely supportive and keen to be involved. We helped Secret World erect temporary 7 metre aviaries into which first the 4 and then the 5th were placed for two weeks to acclimatise. During this time food, dead mice & chicks, had to be put in the aviary, by the rescued-juvenile-b-owlsfamilies, from the supply that was kept in their freezers. After 2 weeks, at dusk the aviary doors were left open. Next morning the Barn owls had left, hopefully to find their own territories and mate. This has been the first time that Secret World and Cam Valley Wildlife Group have worked together in this way and we hope that it will not be the last. Combining knowledge and expertise and working with such wildlife friendly farm owners has been an object lesson in teamwork.

Andre Fournier (Project Leader) 01761 418153 Photographs courtesy of Gary Kingman (except the chick)

With many thanks to the many local helpful farmers and other landowners who make our work possible