Marsh and Willow Tits

As some of you will be aware, I have been studying the bird populations in OS square SN65 for several years. A detailed review of Marsh/Willow Tits was published in the 2013 Bird Report. I've now completed a second survey and can start to compare the two sets of results.For those of you who didn't read the 2013 article (or fell asleep half way through reading it maybe!); briefly, SN65 includes Tregaron, LLangybi, Llanfair Clydogau, LLanddewi Brefi and Llangeitho, as well as a lot of high ground east of the Teifi. It is divided into 25 recording units called tetrads. Willow Tit 2007-12 10 tetrads 10-13 territories 2012-17 8 tetrads 12 territories Marsh Tit 2007-12 7 tetrads 7-12 territories 2012-17 8 tetrads 15 territories Re Willow Tits I know birds exist at Cors Caron, Pontrhydfendigaid, Cross Inn Forest and Bethania. Recently, Chris told me they had one where they live (near Trefenter, I think). I wonder if any of these birds are linked to those in SN65, via places like Penuwch, Blaenpennal, Swyddffynnon and Bronant?