Back in December Arfon Williams (birder extraordinaire and hero of the razzle and dazzle blog post) and Rob Parry (INCCymru) installed a barn owl box in the old sheep shed just off the yard here at Cefn Garthenor. The sheep shed, or railway barn as I call it, is much larger than the traditional stone barns around the main farmyard. It is big and open, designed to take a few hundred sheep for lambing or sheering, and all the uprights are made from old railway track. Until the track was finally taken up in 1975, there was a railway line operating a few hundred metres down the hill, taking milk from the Llanio creamery / dairy down through Lampeter until 1970 (part of the old Carmarthen to Aberystwyth line which carried passengers until 1965). Those iron tracks were rapidly re-deployed by the ever-resourceful local farmers.
Anyway, the barn is butt ugly, no longer houses sheep but at least provides a great vantage point for barn owls, allowing them to look out over the open field and their hunting ground. Barn owls like a big box (this is a box around 70cm / 27” square at the bottom and 90cm / 36” deep) with a small entrance at the top, situated above a ledge. This gives a deep nest which fills with pellets and the remnants of dead rodents over years of use, so probably needs clearing out every two or three years. The idea of the deep box is that the chicks can’t accidentally walk out and drop to the floor before they are capable of flight. Being located in the barn provides extra shelter for the adults and a place they can roost away from the noisy and demanding brood.
Of course, having nest box is no guarantee that it will be used. I knew we had at least one barn owl roosting in the barns around the yard. I’d seen him or her regularly, either roosting or hunting, and clearly the longer grass in our fields was creating a better habitat for voles, mice and shrews. So, there was certainly a great source of food for any barn owls.
Back in April I saw that there were pellets beneath the box and signs of roosting around the barn. I got the camera trap set up but caught very little as it was too far away and the owls either weren’t around or weren’t setting off the motion detector. Fortunately, back in mid-June, Arfon offered to come and check the box. He looked inside (I was too nervous that I might disturb things) and found three chicks which looked just a few days old and one egg still to hatch.
Emboldened I moved the camera much closer, putting a ladder up to one of the rafters and setting the camera up 3m / 10’ from the box. Finally, I got what I was hoping for. Each night, typically between 10pm and 4am, the male owl is out hunting and returning with 10 to 12 voles or mice. Those are hungry chicks! They are also getting pretty noisy … at night you can hear their wheezing sounds.
For the first three weeks, the chicks cannot stay warm, so the mother needs to brood them. The food brought in by the father is ripped up by the mother and fed to them. By three weeks old, an owlet can swallow a small mouse or shrew whole. They can also keep warm, which is a good job as this frees up the mother to help hunt for the increasing hungry kids. Given we have only once caught both mother and father out, I guess we are at this stage which ties in with what Arfon saw.
By 6 weeks the not-so-little buggers can weigh more than the adults, although quite possibly the weakest may have died as a result of too little food being provided. The adults are presumably exhausted and cut back on the food deliveries. The owlets get the message and start flapping. By 8 to 9 weeks they will have made their first flight and by 10 they’ll by pretty good at it. All of this still to come. The Cefn Garthenor pair still have a month or so of constantly refilling the fridge to go. That could easily be another 300 mice, shrews or voles! Even when flying it will likely take a few weeks before the youngsters can hunt for themselves. They get no training (the parents by this stage are presumably shadows of their former selves and are frankly keen to have some me time), so all is based on instinct. By 13 weeks the parents finally breath a sigh of relief as the young ones move out.
Rob Parry was up on Sunday and thought that many of the kills were water voles judging from their size (bigger than mice or shrews). That means that they must be pretty plentiful, here at least, and easy to find, which is great news (especially as water voles are overall in decline). We are clearly getting something right, creating a stronger and fatter food chain.
I’ll report back when, hopefully, those brats fledge! But before that more videos ...
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