Birdboxes in the Blackwater Valley
The Trust has always been interested in the numbers and species of birds nesting in the Valley, and where possible we have tried to encourage them by putting up bird boxes. In the past year we made quite a concerted effort, and there are now approaching a total of fifty on various sites – 11 on Grants Moor, five in Blackwater Park next to Hawley Meadows, nine in Victoria Road Cemetery, 14 at Frimley Hatches Pit 4, and six at Frimley Reedbed. After reading about them, if you want to help with monitoring these nest boxes, and are available during weekdays, then please contact Bernard at the Trust.
The breeding season was delayed by a cold spring, but by the beginning of May eight of the 11 Grants Moor boxes had completed nests with eggs, one Blue Tit box having a total of 13 eggs on the 7th May. Two boxes were not used at all, one being damaged by a Great Spotted Woodpecker which was nesting in a nearby power pole and was probably responsible for the loss of some of the young from certain nest boxes.
Altogether there were six Blue Tit nests and three Great Tit nests. There was a short period of cold wet weather while some of the nestlings were nearly full grown and this coincided with the removal of many trees from beneath the power lines, which made it impossible for the adults to find enough food for them all. Nonetheless most of the nests produced some youngsters with the Blue Tits that had 13 eggs, of which 11 hatched, bringing off nine young. There was one very late nesting pair of Blue Tits which were still brooding five young, from seven eggs, on the 18th June.
At Frimley Pit 4 there were 14 boxes of which three were occupied by Great Tits, raising 11 young, 10 of which were ringed. Of the other 11 boxes, three failed at the egg stage. The remaining eight boxes containing Blue Tits produced 62 young, all of which were ringed. At Frimley Reedbed we placed six boxes. One failed (taken by wasps or something very similar that I didn’t want to identify from close up!), and one was taken up by Great Tits and produced eight young which were all ringed. The remaining four produced 14 young between them of which all were ringed.
Since the ringing was done the following birds have been re-trapped in ringing sessions at Pit 4 – 17 Blue Tits (two have been retrapped 18 times between them!), and three Great Tits. This reflects the propensity of the species not to migrate long distances. Two of the birds, a Blue Tit and a Great Tit, were ringed in boxes at the reed bed site but were re-trapped at Pit 4, having done a little local prospecting for food etc.
Victoria Road Cemetery
This is a more urban site, though it does have large trees within the site and the surrounding area. Nine nest boxes were put up in the spring, seven of the hole nesting type and two open front boxes for Robins. The Robin boxes were not used even though there were Robins around on every visit. The Tits started nesting later, with only three of the seven boxes having eggs on the 7th May, eight, five and one, respectively. One box was not used. Five Blue and one Great Tit finally nested but they seem to have difficulty in finding enough food for their broods, even though they did not lay as many eggs as their countryside cousins. Altogether they only fledged nine or ten from these six nests. It may be that there is not enough food for this number of nest boxes, or it could just be that this year’s rain, arriving at the wrong time, disrupted the life cycle of the small moth caterpillars these birds rely on.
With just five nest boxes in the small patch of woodland at Blackwater Park, I was not expecting much on the first check on 7th May. However all the boxes had been taken by Blue Tits and three of them had already laid 11 eggs each.
Of the other two, one had two eggs on that first visit and the female sat tight on her eggs and young until 4th June, when I saw she had three young. This female had a growth on her face and I was worried she would not survive the nesting season, but the three young were very large on the 11th June and fledged by the 19th. The second of the later boxes was lined on the 7th May and had nine eggs just nine days later, two of which were obviously infertile. This pair fledged all of their seven fertile eggs. One of the 11 egg families managed to fledge 10 young and the other two a more average five and eight.