A history in bones

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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.

Barn Owl documentary, RTE1, next Tuesday

Colin, with a Barn Owl chick, during filming in June of last year, at a Duhallow nest site.

Here's one for the diary – Tuesday 2nd April 2013, on RTE 1 television at 7pm – Wildlife documentary maker, Colin Stafford-Johnson, hosts a half hour long documentary on Barn Owls. Most of the filming was carried out in Duhallow and Kerry in summer 2012. The team followed John Lusby, Michael O'Clery and Brin McDonald as they carried out research and fieldwork during the Duhallow Raptor Conservation Project, and features some amazing footage of Barn Owl nests at two derelict cottages in Kerry and a tree nest in a family's back garden in Cork.

The crew filming John Lusby at a nest site in Co. Kerry. The chicks were down the chimney of the derelict cottage.

Duhallow Report, 2012 now available

The Duhallow Raptor Conservation Project Report, 2012 is now available for free to download. It shows the results from last years project on Raptors in Duhallow, including all the fieldwork, nest box and publicity aspects to the work, many of which you will have seen illustrated on this blog.

Some of the highlights are:

A survey of suitable buildings for Barn Owls highlighted a site availability of 14.6 suitable buildings per 100km2 (range: 8 – 26), and located seven nest sites and 13 roost sites.

A density of 2.6 breeding pairs of Barn Owl per 100km2 was recorded, which is higher than similar findings elsewhere in the country. 

An innovative playback and acoustic survey was also employed for Long-eared Owl for the first time in Ireland. A total of 6 breeding sites and 7 active territories were confirmed, representing a minimum density of 4.3 Long-eared Owl territories per 100km2.

A breeding success of 66.6% was recorded at six known breeding attempts for Long-eared Owl with an average brood size of 2.25 young per brood. 

There were 22 Barn Owl nest boxes in place in Duhallow by the end of 2012, representing one of the highest densities of boxes in the country. 

Ten Kestrel nest boxes were installed at suitable sites which marked one of the first formal nest box schemes for this species.

An awareness campaign promoted  the 2012 project and its objectives, and the work was publicised through posters (136), and a wide range of events and presentations (12), articles in newspapers and magazines (9), and features on websites (2). This blog, www.duhallow.blogspot.com, was also set up to make the project accessible to the general public, and received over 13,000 page views from over 20 countries by December 2012.

To view the lower resolution PDF, see it on this page HERE.

To download the full report, go to this page HERE. (Opens a new window, on www.box.com, where you can view and download the higher resolution file. File size is 17Mb).

Snapshot of the 2012 season

The findings from our fieldwork in Duhallow in 2012 is available to read online, or download (see the post below).

A quick summary of the findings...

15 Barn Owl nest boxes were in place for the 2012 breeding season. Four of these were used as roosts, two as nests. (a 40% uptake).

13 sites were recorded as active during survey work in 2011 and nine of these were still active in 2012. Four were abandoned.

12 new Barn Owl nest sites and 14 roosts were discovered in Duhallow during fieldwork in 2012 – a total of 35 active sites. 20 were nests.

Of the 20 nests, the most common sites were derelict farm houses (9), trees (4), castles (2), farm buildings (2) and one each in a modern unoccupied dwelling, an occupied dwelling and a ruined creamery.

The most common nest site type was roof spaces (7), chimneys (6), cavities in trees (4), nest boxes (2) and one in a water tank.

13 (65% of) nests produced young, lower than the national average.

Of 12 sites monitored, the average number of chicks per nest was 2.16, similar to the national average.

The nest box scheme and particularly the Survey highlight Duhallow to be of national significance for the Barn Owl population, holding one of the highest densities per surface area recorded in Ireland. 

The results of the monitoring work also showed the vulnerability of the local population and the necessity for continued and strategic monitoring as well as further implementation of effective conservation measures to help maintain the status of the Barn Owl in Duhallow. 

Download the full version, below.