Summer Barn Owl Breeding Survey Undertaken

Each summer all the group’s barn owl boxes are visited by our authorised team to determine which ones have breeding occupants within them. From this a record is kept of the stage of development of any young to determine when they are large enough for a return visit to be made to ring and record them. Every box is logged initially and all findings added to our data base to complete the historical record of each one.  Kestrels, jackdaws and stock doves are often inclined to make the most of our effort to assist the local barn owl population and are regularly identified as interlopers. The jackdaws complete their nesting before we arrive and we are often presented with a box almost completely full of the mud and sticks they use to form their nest. These have to be removed entirely and the boxes cleaned of all redundant debris to make them suitable for occupation by owls again. It is always a difficult and very dirty job and produces clouds of dust which totally engulfs the person undertaking it and anyone else in the vicinity. Any old stock doves nests found are also cleared but any doves still residing within a box are left undisturbed to complete their breeding in peace. Even in a location where we had only weeks before erected new boxes we already had a stock dove resident with several eggs.

During our winter inspections we had noted only half the number of resident adult owls compared with the previous bountiful breeding year, so we were expecting the summer breeding population results to follow the same pattern. This indeed proved to be the case. The spring and early summer had been dry and hot and this resulted in a delay in the growth of meadows where their mice and vole prey reside. This in turn affected the prey populations and made food availability for owls less plentiful which affected the size and frequency of owl broods. In some cases the number of barn owl young found on our initial inspections had reduced further by the time we returned to ring them and it was suspected that some smaller siblings had been sacrificed to compensate for the food shortage. We found no larders of dead mice and voles this year which further adds weight to this theory.

The first box visited however had a really healthy brood of young kestrels in it. These are very fiery even at a very young stage of growth and make a lot of noise to try to force us to leave.

Young kestrels huddling together for protection.

 

When we returned to ring them several weeks later they demonstrated even more defiance.

Several boxes were found to contain broods still at the egg stage. This meant we had to stagger our return visits as ringing can only be undertaken when they reach a suitable size and each box contained young at vastly differing stages of development. This development difference even occurs within a single box depending on the timing of individual egg hatching.

 

Five barn owl eggs found in one box.

 

Three eggs found in another.

 

Four kestrel eggs found in a further box. These unfortunately had been abandoned by the parents, probably because the box was occupied by an adult barn owl at the time of our initial visit.

 

This was a young stock dove resident found enjoying the safety of a barn owl box to develop. It was left undisturbed.

 

This was one of the many boxes found with young barn owls within it. At this size it was several weeks before they were sufficiently large enough to ring.

 

This was one found in another location having grown enough to develop much of its adult plumage. This one was revisited fairly quickly to ring it before it fledged.

 

By the time we had returned to record this owl it was already showing evidence of having undertaken an exploratory flight in the world outside the box. This could be determined by the cleanliness of its feet. They become very dirty during their time inside the owl box and need a hunting trip to clean them.

 

 It had fully formed and decidedly sharp talons which immediately became evident to us during its handling. 

Each fully grown young owl we are able to ensure develops to maturity is another boost to the fragile continuity of the species in an increasingly hostile world. Without such conservation initiatives they would be struggling to survive so we are encouraged to continue with the considerable effort we currently expend. Our supporters often generously help with donations to assist us with the expenses we incur to achieve this. We are obviously very grateful for this.

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