If you've seen a blue tit darting back and forth with bits of moss in its beak, chances are you've caught them in the midst of their carefully timed nesting season.
These charismatic little birds start scoping out potential nest sites as early as January, checking every hole and crevice between 1 to 5 meters off the ground.
You might even spot them investigating drain pipes or gaps in walls - they're not fussy about location as long as the entrance hole is just right, ideally around 25mm wide.
Subscribe to our YouTube channel| Key Blue Tit Nesting Facts | |
|---|---|
| Nesting season | March to June |
| Nesting material | Moss, soft foliage, wool and feathers |
| Nest type | Cavity |
| Nest location | Tree hollows, buildings, nest boxes |
| Number of broods | One brood |
| Clutch size | 8 - 10 eggs, ranges up to 13 |
| Egg colour | Pale white to cream with light brown speckles |
| Egg size | 16 x 12 mm |
| Egg weight | 1.1 g |
| Incubation period | 13 - 15 days, by the female |
| Fledgling period | 18 - 21 days |
| Reuse nests | Usually not, but will breed in same territories |
| Use nest boxes | Yes |
Blue Tits frequently use cavities to build their nests in
Watch a garden with nest boxes in early spring, and you'll see quite the performance. Females inspect every possible cavity, spending up to two weeks finding just the right spot.
Watch closely and you'll notice the male following along, singing to defend his territory while she does all the hard work of checking each potential home.
They're surprisingly picky about flight paths, too - the perfect nest site needs a clear approach, away from the watchful eyes of local predators.
A nesting pair of Blue tits using a nest box
Once they've chosen a spot, the real work begins. Blue tits transform these empty spaces into cosy nurseries, with the female spending nearly two weeks gathering materials.
You might spot them gathering moss from old walls, pulling apart fluffy seedheads, or even making off with stray pet fur left on garden bushes.
Each nest becomes a masterpiece of natural engineering - a deep cup of moss lined with the softest materials they can find. The female works in layers, starting with green moss and soft vegetation before adding the final luxurious lining of feathers, wool, and even spider webs.
Once the nest is perfectly lined, the female begins the demanding task of laying her clutch. Each morning brings a new egg - small, speckled treasures about the size of your fingernail.
They're beautiful things, cream-coloured with delicate brown speckles that cluster towards the rounder end. Watching a female blue tit during this time, you might notice her making fewer trips outside - she's busy laying these tiny eggs, each one weighing about a gram, nearly a tenth of her own body weight.
Over the course of about two weeks, she lays between 8 and 12 eggs, sometimes even up to 16 in a really good year. Then comes the patient part—she spends the next two weeks hardly leaving the nest, keeping her eggs at just the right temperature for incubation.
During this time, you might spot her mate bringing her food, though some females prefer to nip out for quick feeding breaks themselves.
The nest of a Blue Tit inside a nesting box, with a large clutch of eggs inside
The timing of their nesting is remarkably precise. Blue tits synchronise their breeding so their chicks hatch just as spring caterpillars emerge on oak trees.
A single pair might bring their growing chicks up to 1,000 caterpillars in a day - you can often see them making endless trips back and forth, their beaks stuffed with green treasures for their hungry brood.
With anywhere from 8 to 12 hungry chicks to feed, there's no time to rest. The earliest hatched chicks often have the best chance of survival, so you'll notice parents focusing on the loudest, most demanding beaks.
Young Blue Tit chicks inside a nest box
Keep an eye on nearby oak trees around May - you'll often see them acrobatically hanging upside down, checking every leaf for food.
The chicks will stay in the nest for about 18 to 21 days, and during this time, both parents work tirelessly.
The female continues to brood the chicks while the male does most of the food gathering, though she'll join in the feeding frenzy as the chicks grow larger.
Adult Blue tit feeding a recently fledged chick
Come June, gardens suddenly fill with the high-pitched calls of newly fledged youngsters, still begging their parents for food even though they're almost the same size.
Those pristine nest boxes that were so carefully investigated back in winter now bear the marks of a season's hard use.
Though they rarely reuse the exact same nest, successful pairs often return to the same territory year after year - but they'll be ready and waiting for next spring's nesting season to begin all over again.
A Blue Tit gathering nesting materials to construct the nest
Do Blue tits abandon their nests?
Blue tits do sometimes abandon their nests. Complete brood failure in Blue tits occurs around 13% of the time, according to one study of 684 nests. In most situations, one parent had left or disappeared while the chicks were still alive.
If one parent dies, it might be challenging for the other to raise the brood on their own. However, birds rarely abandon their reason without a highly compelling cause, however, and even single parents can successfully raise a brood if one of them dies during the breeding season.
In this situation, the remaining single parent might abandon the nest altogether. Unfortunately, some nests are also lost to predation, meaning the parents have no other choice than to abandon them.