As part of the Duhallow Raptor Survey this chimney in Duhallow was checked for Barn Owls yesterday. Almost half of the known nest sites in Ireland are in chimney shafts of abandoned buildings.
Jackdaws can prove to be a problem for Barn Owls when they fill otherwise suitable chimneys and cavities with sticks and other debris in an attempt to reduce or block the shaft, when they can then nest on top of the material.
In some cases whole chimney structures, as well as Barn Owl nest boxes, have been filled almost to the top by these industrious birds - a perfect space for a Jackdaw to nest, but no longer room for a Barn Owl to do so.
The Jackdaw's instinct to fill such cavities sometimes results in truly enormous piles of sticks below chimneys or other shafts which have accumulated over the years. The Jackdaws will either eventually give up or the shaft finally becomes blocked or filled and they can then nest on it.
Below, a video of a chimney shaft in Duhallow where the Jackdaws have inadvertently created an ideal nesting ledge for Barn Owls about 2m (6ft) down inside the left hand shaft of the chimney of an abandoned cottage. Should any Barn Owl come across this site, they could quickly evict the Jackdaws and move in. Barn Owls are actually very good climbers and the rough stone walls of this chimney should present no problems to them.
Chimney shaft of an abandoned cottage, Duhallow, 20th April (M.O'Clery).