At first glance the acrobatic and cheeky Blue Tit is a blue and yellow bird.
A closer inspection reveals bright blue wings, tail and crown, yellow underparts, greenish back and mantle, white cheeks, and black eye stripe, bib and collar. They also have a black streak down the middle of the belly, and a white wing bar (across the coverts). The bill is black and the legs are a blue-grey.
The sexes are similar, though the female is slightly paler.
The juvenile birds are duller than the adults and have greener crown, wings and tail, and yellow cheeks.
| Scientific Name | Cyanistes caeruleus |
| Length | 11.5 cm (4½") |
| Wing Span | 17.5-20 cm (7-8") |
| Weight | 9-12.5 g (¼-½oz) |
| Breeding Pairs | 3300000 |
| Present | All Year |
| Status | Green |
The Blue Tit's song is "tsee-tsee-tsu-hu-hu-hu-hu" and can be heard all year round. The alarm call is a churring sound.
Blue Tits feed mostly on insects, especially caterpillars, and seeds. In springtime they feed also on pollen, nectar and sap, and in the autumn on berries.
In the garden they search among the plants and crevices for insects (e.g. aphids, beetles, and caterpillars) and spiders, but also take sunflower hearts or high energy seed from bird feeders, or peck at a suet food bar or peanuts.
They are one of the most agile birds, and they will entertain for hours by hanging upside down from feeders, branches, etc. They are also opportunists and will often peck through foil milk bottle tops for the cream.
Blue Tits, and other tits, also peck putty around windows, usually at winter time. Some may simply be hungry and attracted to the linseed oil in the putty, though it is thought more likely that they are simply searching for food.
Blue Tits will nest in any hole in a tree, wall or nest box. They are well known for nesting in more unusual places, such as letter boxes, pipes, etc. The nest is a cup made by the female from moss, wool, dead leaves, spiders' webs, and lined with down.
Their clutch size is the largest among nidicolous species, laying typically 10 to 12 eggs. The eggs are laid at such a time that green caterpillars will be abundant when the chicks hatch. Second clutches are rare.
The eggs are smooth and glossy, and white with purplish-red or reddish-brown spots. They are about 16 mm by 12 mm. The female incubates the eggs by herself. After the young hatch, they are fed by both parents.
| Breeding Starts | Clutches | Eggs | Incubation (days) | Fledge (days) |
|---|---|---|---|---|
| mid-April | 1-2 | 5-16 | 12-16 | 15-23 |
The Blue Tit is resident and does not usually wander more than a few kilometres far from its natal (birth) place.
Blue Tit populations often decrease considerably during harsh winters or after poor breeding seasons where the weather is cold and wet, particularly if this coincides with the emergence of the caterpillars on which the nestlings are fed.
