Two visits to the woods at Roeburndale this weekend saw a welcome increase in the number of Blue Tits after worries about their low numbers earlier in the winter. 80 birds caught, of which 6 were Coal Tit (a very low number for this site), 41 Blue Tit and 20 Great Tit. Of these birds, the breakdown of new and retrapped birds broken down by age class is as follows:
Coal Tit no new birds, retrap - 1 juv, 5 adult
Blue Tit new birds - 12 juv, 5 adult; retrap - 15 juv, 9 adult
Great Tit new birds - 2 juv, 2 adult; retrap - 9 juv, 7 adult
This suggests that juvenile birds did survive until winter in good numbers. Low numbers earlier in the autumn and winter were possibly related to a very good food supply in the woods (we were still being bitten by insects well into November) meaning that Blue Tits stayed in the canopy feeding on natural food until late on in the season.
Rather oddly, very few nestlings from the many boxes in this valley are ever caught in winter in these woods - we still don't know where they all end up!
Paul
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