This year has been the most successful yet for breeding occupancy in our barn owl boxes. Not only have we had a record number of barn owl young born in our boxes, we have also had a large number of kestrels who are also in decline nationally with only 1 in 3 born surviving beyond 3 months. We also have found evidence of little owl breeding at some of our locations. With results like this, the tortuous winter maintenance schedule involving pulling heavy equipment over many soggy fields to visit, clean and maintain all of the boxes within our area are quickly forgotten.
Our demanding winter maintenance schedule to maintain each box within the barn owl conservation area provides the basis for our breeding success.
Four barn owl eggs found on an initial breeding survey this summer.
Three kestrel eggs found during the same tour around all the boxes.
Four little owl eggs found in a tree hole near to a barn owl box.
We also check on the large number of tawny owl boxes mounted within woodlands in our conservation area, but unfortunately many of these have been taken over by grey squirrels who constantly inflict structural damage to the boxes, making them far less productive in breeding terms and dramatically shorten the life of the boxes. Despite this, we have continued to provide these boxes in areas that aren’t plagued with a squirrel presence.
A tawny owl box mounted in a wooded area.
With kestrels and tawny owls beginning their breeding season before the barn owls, our box visits commence at different times. Kestrels tend to favour regular occupancy of specific boxes, so these can be visited a month earlier than the other barn owl boxes along with the tawny owl box checks. This year however, the barn owl boxes that they regularly breed in were not the only ones they occupied, so when their presence was discovered during the later round of barn owl box inspections, many had reached an advanced stage of development. This meant that with their feisty disposition, they would be difficult to deal with to record. It also meant a rapid return to this location, armed with equipment to undertake this recording, was required.
Three kestrels found that had reached an advanced stage of growth.
We have strong memories of two of us returning quickly to one such location this summer where this had occurred, visiting at 6.30am to catch them before they fledged. We carried ladders and bags of recording equipment across two large fields only to discover that the 5 kestrel chicks had already departed their nest on our arrival. During the long trek back we reflected that the start of this recording session was not the one we had wished for.
All boxes in the barn owl conservation area are initially checked in early summer.
The first visit to each box establishes whether breeding has occurred within them. On this visit their development progress is noted and a return visit date is calculated to establish the perfect stage of development for ringing and recording them. Ideally this is when they are large enough to sex, measure, weigh and ring them, but not too large so that they are difficult to handle. This is not always easy to establish as barn owls begin incubating their eggs, which can number between two and six, as soon as the first one is laid.
An initial clutch of barn owl eggs found this year.
Incubation of the eggs lasts for a period of between 18 to 21 days. After 31 to 33 days of incubation, the eggs hatch at a rate of one every 2 to 3 days. The age difference between the oldest and youngest can therefore be up to 3 weeks. This means that within one box all the young are at a different stage of development, so an average age and size has to be determined to calculate the date of the return visit.
When the chicks hatch they are mostly bald and with eyes tightly shut. They need the attention of the parent to keep them warm until they produce sufficient down to maintain their own body temperature.
The difference in sizes can be a problem for the youngest chick, for in times of food scarcity they are often consumed by their larger siblings. In many cases we find that in a box initially housing 6 youngsters, the return visit finds that only a couple are remaining with no sign of the others. This can be due to predation by an external species but usually is the result of a larger, hungry sibling.
A typical variation in barn owl sizes found in one box this year.
Five young kestrels found in a barn owl box this year nearing the preferred size for recording them.
These breeding visits are undertaken by trained and qualified permit holders who undertake nest site recording and occupant ringing for most of the summer from May until August. Barn owls are a Schedule 1 protected species and must only be disturbed by trained people holding the required certification to ensure their continuing welfare. Other volunteers often join them to assist with the activity and help with equipment carrying.
The parent barn owls usually detect our approach on these initial visits and fly out of the box before our inspection.
With the number of repeat visits required to achieve this monitoring, many volunteers are called upon to form the recording teams. So successful have we been with this project since we began in 2007, that barn owls are no longer on the endangered species list, but instead are now regularly seen in our local countryside. It has been a very hard and time consuming project but one that has made all the effort justified.
A barn owl flying along a field hedgerow from a nearby box.
Another one who chose to leave before we arrived at its nest box.
All young barn owls and kestrels found this year were duly ringed and recorded with the results submitted to the national British Trust for Ornithology. Pictures of some of the recording activity encounters are included below.
On the initial inspection we make no attempt to record the adults, although their presence and location are noted.
Some remain in the box until we are about to open the door. In these cases we often get covered in excrement as they invariably discharge themselves when suddenly flying out.
When the barn owl chicks are just hatched, they are very vulnerable as seen here.
They huddle together for warmth and security.
Similarly kestrels find safety and increased temperature in a group.
On odd occasions we find boxes containing late developing young jackdaws. Not our favourite discovery due to the considerable mess their mud and twig nest building creates inside, but we leave them undisturbed to continue their development.
This box contained the ideal result we seek. Four strong and healthy barn owl chicks advancing towards adulthood and the perfect size to record.
These were kestrels we returned to ring and record after the initial visit. They have just been gently returned to their box after having had identification rings attached to their legs.
Similarly, recorded barn owls are carefully returned to their nest box after ringing. They always gather together when they initially are placed back in their home.
They soon perk up however, when we close the door.
The ringing and recording visits are the best time for us…..
….as this is the time we can get close enough to examine them to make sure they are healthy and happy.
It also allows us to appreciate the beauty of this wonderful species.
This is the first time most of them have seen the world outside their box….
.…so they gaze around absorbing the new sights and sounds.
Then we return them to the secure environment they are familiar with.
Kestrels undergo this experience too….
….and after being sensitively ringed and recorded are also place back in the safety of their boxes.
Each small barn owl is gently weighed, measured, sexed and their details recorded.
The activity allows each to have their health checked to ensure they have the best chance of fledging.
This time spent with each owl is precious to the recording team and provides a gratifying return for the conservation effort expended.
Each downy handful held at the recording stage will hopefully develop into a magnificent adult….
….and eventually produce young of its own to further increase the barn owl population in our surrounding countryside.
It is this objective that drives our project to help all these wonderful creatures in a diminishing countryside landscape that is progressively threatening their survival by robbing them of the habitat they need to exist. Without this support they would probably be on the verge of extinction, as are so many other species currently.