Birds

Blue Tit

Cyanistes caeruleus · also called Eurasian blue tit

Least Concern ↑ omnivore Temperate forest Temperate grassland

The blue tit is the small, quick, blue-capped bird that turns a peanut feeder into a gymnastics display, hanging upside down and sideways to get at the food. It is one of the most familiar garden birds in Europe, and one of the most closely studied, because it nests in boxes and its fortunes rise and fall with the spring weather.

Overview

Cyanistes caeruleus is a tiny member of the tit family, about 11 to 12 cm long, with a blue cap, wings, and tail, a yellow breast, a greenish back, and a white face marked with a dark eye-line. It lives in woodland, hedgerows, parks, and gardens across Europe, North Africa, and western Asia, and it does not migrate. In summer it eats caterpillars and aphids; in winter, seeds, nuts, and feeder fat.

Built for the twig-tips

At only 11 grams, the blue tit can feed where heavier birds cannot — on the thinnest outer twigs and the undersides of leaves, exactly where small caterpillars hide. The same lightness makes it a natural on hanging feeders. Its blue crown reflects ultraviolet light that birds can see and we cannot, and brighter crowns signal a fitter male.

One brood, timed to the minute

A pair raises a single large clutch of up to a dozen eggs, timed so the chicks hatch at the brief caterpillar peak in the tree canopy. A cold, wet spring can wipe out that food supply and starve a whole brood, which is why blue tit numbers swing sharply from year to year. In 20th-century Britain, blue tits famously learned to open milk-bottle tops and spread the trick by copying.

Status

The blue tit is Least Concern and stable or increasing, one of the commonest garden birds in Europe, helped by feeding and nest boxes.

Blue Tit: common questions

What is the difference between a blue tit and a great tit?

Size and colour. The blue tit is small and dainty, about 11 to 12 cm, with a sky-blue cap, wings, and tail, a white face crossed by a thin dark line through the eye, a greenish back, and a plain yellow breast. The great tit is noticeably bigger and chunkier, about 14 cm, with a glossy blue-black head, broad white cheeks, and a bold black stripe running down the centre of its yellow breast. Both come to the same feeders and often together, so a side-by-side look makes it obvious, with the great tit the larger one with the black head and black belly stripe and the blue tit the smaller one with the blue cap and no stripe.

Why does the blue tit hang upside down to feed?

It is light enough to do so, and it pays. A blue tit weighs only about 11 grams, so it can perch on the thinnest outer twigs and cling to the underside of leaves and buds without them bending away. Many of the small caterpillars and aphids it feeds on live exactly there, on the undersides and tips of foliage, out of reach of heavier birds like sparrows or finches that need a solid perch. The same agility is why blue tits are so comfortable on hanging peanut feeders and fat balls, which they can work from any angle.

Why do so few blue tit chicks survive some years?

Because the whole brood depends on a brief, weather-sensitive food supply. Blue tits feed their nestlings almost entirely on small caterpillars, and in an oak wood those caterpillars are abundant for only a week or two in spring before they pupate. The parents try to time hatching to that peak, but if a cold or wet spell arrives, it can knock back the caterpillars just as ten hungry chicks need feeding, and much of the brood starves. In a mild, well-matched year the same pair may fledge a full nestful. This is why blue tit populations rise and fall so much between years.

Will blue tits use a nest box, and what kind?

Yes, very readily. Blue tits are cavity nesters that naturally use holes in trees, and they take to a wooden nest box with an entrance hole of about 25 to 28 millimetres, which is small enough to keep out great tits and house sparrows. The box should be fixed 2 to 4 metres up on a tree trunk or wall, facing somewhere between north and east to avoid the midday sun and driving rain, and away from feeders and obvious cat perches. Put it up by late winter, since blue tits begin prospecting for sites well before they lay in April. Clean it out in autumn once the young have gone.

Sources & further reading

Written by HideShark Editorial Team · reviewed by HideShark Science Desk. Published October 24, 2026. Last updated October 24, 2026.

Quick facts

Scientific name: Cyanistes caeruleus
Diet: Small caterpillars, aphids, spiders, and insect eggs through spring and summer, especially to feed nestlings, and seeds, nuts, and fat in autumn and winter; blue tits are constant visitors to peanut feeders and fat balls
Colours we cannot fully see: The blue crown reflects ultraviolet light, which birds can see and people cannot, and males with brighter UV crowns tend to be in better condition, so the cap works as a signal of quality that is partly invisible to us
An upside-down feeder: Light and agile, the blue tit works the very tips of thin twigs and hangs beneath leaves and buds to reach insects that heavier birds cannot get at, which is why it is so at home on a swinging peanut feeder
One big brood, precisely timed: A pair raises a single clutch of up to 10 to 12 eggs, and they time laying so the chicks hatch at the peak of caterpillar numbers in the oak canopy, a window of only a week or two that determines how many young survive
The milk-bottle trick: In twentieth-century Britain blue tits and great tits learned to peck through the foil caps of doorstep milk bottles to drink the cream, and the habit spread from town to town as birds copied one another
Boom and bust: Blue tit numbers swing sharply between years because a cold, wet spring can kill most of the caterpillars and starve whole broods, while a mild one produces a bumper crop of young
A garden favourite that stays put: The blue tit is a resident bird that does not migrate, holding a small territory year-round, though in autumn small flocks of tits and other birds roam the woods together, and northern populations occasionally move south in numbers
Range: Woodland, hedgerows, parks, orchards, and gardens across Europe, North Africa, and the Middle East, and east into western Asia; it is a resident, non-migratory bird through nearly all of this range.
Conservation status: Least Concern ↑ ≈ Very large and generally stable or increasing across Europe, one of the most numerous and familiar garden birds in Britain and much of the continent, helped by garden feeding and the widespread use of nest boxes in the wild