The Great Tit is one of our best known and most studied garden birds, thanks to their liking for nest boxes we have been studying them for a hundred years or so!
The Great Tit is a typical tit and is unmistakable given its larger size. They have a black cap (glossy in males), collar and bib set with white cheeks. The back is green to blue-grey. Underneath they are lemon yellow with a central black stripe running down from the throat which is wider and more strongly developed in males than in females. Sometimes you can see that in the male the black stripe extends across the belly to the base of both legs, while in the female it is not so broad and does not reach the legs. It is this stripe, together with the black head that differentiates them from their smaller cousins, the Blue Tits, and is an indicator of fitness to females.
The most important time of year for Great Tits, is the breeding season, which starts in March with pairing and nest hunting. They nest in holes and crevices in walls or trees, as well as in pipes and letterboxes: which is probably why they also like nest boxes witha clear flight path and a hole around 28mm diameter.
The nest is mainly built by the female and consists primarily of moss, lined with feathers. It can take anything from a few days to a couple of weeks to build.
They make only one breeding attempt, laying 7-9 eggs, timed to coincide with the maximum availability of caterpillars which are the primary requirement for their young. Hence their problems last spring when it was so wet and cold that there were too few of them around.
They are the largest of our tits, with a substantial vocal repertoire. At this time of year their characteristic “tea-cher tea-cher” song is all around us; other calls abound though, a frequent one being “cha-cha-cha”, but all are simple riffs.
Great Tits tend to feed lower down in the undergrowth than other tits, presumably because they are larger and less agile, eating invertebrates when available, and seeds when they are not. Although sociable birds, they don’t form foraging flocks, and their behaviour around feeders is decidedly hierarchical with the dominant adults feeding on the best feeders (closest to cover) leaving the younger birds to feed on more exposed ones where the risk of Sparrowhawk attack is greater.
Great Tits have become susceptible to avian pox over recent years. It has long been endemic in Blackbirds and Dunnocks, but this seems to be a different and more virulent strain leading to unsightly growths on a bird’s head. Since Great Tits do not migrate, it is likely to have been brought to the UK by insects. Although birds can recover from the pox virus, the lesions it causes may impair their vision and ability to feed, as well as leaving them susceptible to secondary infections and predation. To date is does not seem to be species threatening, but if you do see a case please consider reporting it to the BTO or RSPB.
Mike Gray 07596 366342