Coed y Bedw is a 16.5ha ancient woodland reserve just north of Cardiff. Nest boxes of various types have been installed here since at least 1985, soon after WTSWW purchased the reserve.
The volunteer warden at the time installed nest boxes for the benefit of Pied Flycatchers (Ficedula hypoleuca) who were known to breed at the reserve. This charismatic migrant is a feature of mature woodlands in the west of the UK where in feeds primarily on caterpillars and other invertebrates.
Since then, the nest boxes have been replaced as they’ve degraded, with additional ones installed in the reserve as well as in the open woodland and lines of mature trees in the neighbouring land (with the kind agreement of the landowner). At the moment the number of boxes is 120 which includes 2 Tawny Owl boxes, 1 Barn Owl box, a couple of specialist boxes for Redstarts (Phoenicurus phoenicurus) with the remainder being more traditional boxes made either of wood or more recently the longer-lived woodcrete boxes.
The number of Pied Flycatchers on the reserve has declined over the years but nonetheless WTSWW and our hard-working volunteers try to monitor a selection of the boxes every spring to see if Pied Flycatchers appear. The events of 2020 meant that we were unable to carry out this monitoring unfortunately so we relied on our winter box checks to give us an indication of how many boxes were used. It’s good practice to clean out nest boxes in autumn once their occupants have left as the nesting material can harbour parasites.
We try to do this every winter at Coed y Bedw which is quite a mammoth task and is made a lot easier by our committed volunteers whose eagle-eyes make finding them all a lot less time-consuming!
Unfortunately this year that wasn’t possible but we managed to get to all the boxes eventually. It was gratifying to see that about 80 had been used for breeding last year. It’s possible to tell, to a certain extent, what has used the box by what remains – there are often unhatched eggs or bits of shell which can be characteristic; Blue Tit and Great Tits are the commonest residents with their mini egg-like shells.
Pied Flycatchers’ eggs are glossy blue and sadly none were found this year. The other common residents are Nuthatches whose nests are made of woodchips and bits of leaves compared to the moss, wool and hair generally used by the other species. Nuthatches often build up a layer of mud around the entrance hole too which is a definite sign of their presence.
Pleasingly, we also saw a Tawny Owl using one of the specialist boxes that had kindly been built by the students at Pencoed College and we subsequently managed to get a clip of it on a motion-sensitive camera. The only downside is seeing how bad a state many of the wooden boxes are getting, with at least 40 in need of repair or replacement.
We are hoping to be able to gradually replace all of these with long-lasting woodcrete boxes but that’s all dependent on funding sadly. In the meantime we’ll keep monitoring annually, hopefully with the help of the volunteers this coming year.