The mystery site gets more mysterious

Barn Owl roost site in a quarry, Duhallow, 29th April (Michael O'Clery).

At this time of year, male and female Barn Owls will often roost together at the nest site just before laying eggs. The is probably the male 'minding' the female, ensuring that he is the father-to-be of any chicks. This site in Duhallow caused a bit of head scratching last summer (see this post HERE), but the mystery deepened further when two Barn Owls were seen roosting here a few days ago just under the lip of the quarry (circled).

There is no apparent nest site at the quarry, though there is a known nest site in a tree not too far away. However, if this is the pair which are going to nest in the tree, they are taking a risk of losing the nest, whether to other Barn Owls or, more likely, to Jackdaws taking it over after filling it with sticks.

So the puzzle persists, and only further observations will tell us what is going on here...

A history in bones

Click the image for a closer view

Pellets and bones, Duhallow 27th April 2013 (Michael O'Clery).

Ww know of several sites where Barn Owls have been in residence for 20 or more years. Not the same birds of course, as wild Barn Owls will rarely live longer than five years, but rather, continuously occupied by Barn Owls.

The Barn Owl site visited yesterday, in a derelict cottage in Duhallow,  was only discovered by us three years ago. However, a close look at the floor below the nest entrance reveals an interesting story. As you can see, there are fresh pellets (the darker, blackish ones), showing the site is still occupied. Older pellets slowly turn grey, and over a few years, the pellets slowly crumble until only tiny bones remain. These can linger in dry sites for many years, and here the floor is completely covered in a thin layer of tiny bones and skulls from rats, mice, voles and shrews.

The years of accumulated pellet debris shows us that this site has been occupied for many years, at least five, and possibly much longer. There must be the remains of thousands, perhaps tens of thousands of small mammals scattered on the ground.

Jackdaws help Barn Owls

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).

Long-eared Owl constant calling

Below, a short video taken at dusk this evening. With the sun gone down, the final chorus of Blackbirds and Robins is accompanied by the coarse, wheezing calls of a female Long-eared Owl. This sounds a little like a Collared Dove, but is much 'throatier' and lower pitched.

It's nearly dark, and a female Long-eared Owl calls every few seconds. The bird itself is hidden in the foliage, about two thirds the way up the right spruce (Video: Michael O'Clery).

While the female called almost continuously for a full hour, the male only called three times during that period – a mournful "HOOO!". These birds were at a site in Duhallow where they had occupied an old Hooded Crow nest, but  failed to breed last year, perhaps because of the heavy rain (see this post HERE for more).

Long-eared Owl season kicks off

Two sites were visited last night as part of the ongoing Duhallow Raptor Survey, and three Long-eared Owls were detected.

Adult Long-eared Owl (Richard T. Mills).

At the first site, a male and a female owl responded to a tape recording of their calls. This is done under licence from the National Parks and Wildlife Service, and is only done for a brief time so as not to unduly disturb potentially nesting birds. One of the calls from a male was within a couple of hundred metres of one of last years nests (see this post HERE).

At the second site, although the tape was played, there was no response, but a male Long-eared Owl called several times, about 300m from one of last years nests (see this post HERE).

So, an encouraging start to the follow-up survey work in Duhallow. Two of the nests form last year have owls still in the vicinity. There is every chance they will breed again in these areas, and might even be on eggs at this stage, though with the recent cold weather, this may have been delayed.

A quarry box for Kestrels

Kestrels have been roosting at this small quarry site (visible in the lower part of the photo) for several years, and there were fresh signs of their presence yesterday. With our newly acquired Kestrel boxes from the ABI group in Castleisland (see post below), we decided to put one in place and see if the Kestrels take to it. It seems there is no actual suitable nest site in the quarry. With the cold spring, most birds are slow to start breeding, and just perhaps there will be enough time for them to get used to this box and move in.

ABI Group help out with nest boxes

The Acquired Brain Injury group (ABI), based in Castleisland, Kerry, have made a huge contribution toward the Duhallow Raptor Conservation Project by making 10 Barn Owl boxes and 9 Kestrel boxes for use throughout the Castleisland area and beyond. It is hoped they will all be installed by this summer. Uptake of these types of boxes has been very high, so it is possible that many will be occupied within a year or two. Fingers crossed.

A big thank you to Glen and all at the ABI for all the hard work!

Barn Owl doc on RTE Player

If you missed the half hour RTE documentary on Duhallow Barn Owls, you can catch up with it HERE (opens a new page on the RTE website).

It is available online until 23rd April 2013.