A Blue Tit diary

Hazel McCambridge walks through the diary of an average Blue Tit during the breeding season.

Blue Tit in flight. Philip Croft

Hazel McCambridge

Scheme Support Officer & Sustainability Officer

Hazel is the lead organiser of Nesting Neighbours, and works on data collection and volunteer communication as Scheme Support Officer for several projects: 

  • Acoustic Pipeline
  • Ringing Scheme
  • Nest Record Scheme

She is also BTO’s Sustainability Officer and author of the Blue Tit Diary.

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May and June are busy times for Blue Tits. With eggs to incubate and young chicks getting bigger by the day, the demand for food is constant. Whilst these months mark the end of their breeding season, when do Blue Tits start nesting?


  • Finding a partner and a place to nest

Blue Tits start searching for a safe, warm site to start building their nest. The location is important as they require a clear flight path to the nest’s entrance hole and the site must be relatively inaccessible to predators.

Finding the perfect partner is also a top priority at this time.

February — looking for the ideal home.


March — time to fatten up.
  • Feeding up for the breeding season

Birds need to be in prime condition at the start of the breeding season.

Placing bird food in the garden, particularly suet, peanuts and black sunflower seeds, provides a valuable source of nutrients and energy. This can be used by females to produce eggs and keeps both parents in good condition so that they are able to supply enough food for their chicks.


  • Building the nest

The female Blue Tit builds the nest alone with little or no help from the male. She takes materials like moss from garden lawns and forms them into a cup. The nest is complete when it is lined with soft feathers, fur or wool.

Blue Tits can build a nest in a few days, but generally, it takes them between one and two weeks.

The female Blue Tit builds the nest alone with little or no help from the male.  
April — collecting feathers to line a nest.

Early May

Early May — an egg a day.
  • Laying a clutch of eggs

This is an exhausting time for the female. She lays one egg a day, usually first thing in the morning.

Blue Tits have one of the largest clutch sizes of all birds — up to 16 eggs! However, the majority of clutches contain 8–12 eggs.

Mid May

  • Incubating the eggs while they develop

The female plucks feathers from her abdomen to create a bare patch with a good supply of blood vessels (called a ‘brood patch’) which helps her to keep the eggs warm as she incubates them. 

She starts incubating the clutch a day before it is complete and will sit on the eggs for about two weeks until they are ready to hatch.

During this time, if she made a good choice of mate, the male will bring her some food, but she will still need to leave the box regularly during the day to feed.

This is an exhausting time for the female. She lays one egg a day ... up to 16 eggs!  

Late May

Late May — newly hatched young are featherless and blind.
  • Tending the newly-hatched chicks

The chicks hatch naked and blind; as they are so vulnerable at this time the female will frequently sit on them to keep them warm. If the weather is particularly cold and wet finding enough caterpillars to help them grow can prove difficult.

Trends show that on average spring is arriving earlier due to a changing climate and in turn trees’ leaves open earlier, providing food for caterpillars earlier, so that they in turn peak in abundance earlier in the year than previously.

Blue Tits have started to breed earlier too, but their shift has not kept pace with that of the peak abundance of caterpillars. BTO research is investigating the implications of this ‘phenological mismatch’ for Blue Tits and other species.

Each chick can eat 100 caterpillars a day, so to feed a brood of ten, adults need to find as many as 1,000 caterpillars a day.  
End of May — busy parents bringing food for their young.

End of May

  • Feeding the hungry chicks

Feeding chicks takes its toll on the parents as they flit in and out of the nest box with juicy fat caterpillars. Each chick can eat 100 caterpillars a day, so to feed a brood of ten, adults need to find as many as 1,000 caterpillars a day.

Adults also need to remove the chicks’ faecal sacks to keep the nest clean.

By now the chicks’ feathers are well-developed and they are starting to look like they might be capable of flying.

Early June

  • Time for the chicks to fledge

When the chicks are ready to fledge, the parents will call from outside the box, urging them to come out.

One by one each chick will poke its head out and make their first tentative flight (usually badly) to the nearest available perch.

Blue Tit chicks typically fledge when they are 18–21 days old.

June and July

  • Caring for chicks outside the nest

Fledglings stay with their parents who continue to feed them for a few weeks after they have fledged.

This is a dangerous time for young birds. They need to learn how to find food and avoid predators quickly if they are going to survive.

If available, they may take advantage of peanuts and sunflower seeds provided in gardens to build up their strength.

June and July — the fledged chicks continue to grow.

Rest of the year

What do Blue Tits do for the rest of the year?
  • What do Blue Tits do in autumn and winter? 

Blue Tits tend to be quite sedentary birds, staying close to where they hatched as chicks, but some individuals do migrate, so the Blue Tits you see in winter might have hatched or bred elsewhere in northern Europe.

Winter is a tough time for many species and Blue Tits are no exception. Blue Tits in urban settings rely heavily on food provided in people’s gardens at this time, and may also use nest boxes in winter for shelter, especially during the night.

  • How long do Blue Tits live? 

Almost two-thirds of young Blue Tits will not survive their first year of life, but those that do usually start to breed the spring after they hatched.

Blue Tits typically live for three years, but the maximum age recorded from bird ringing is 10 years, 3 months and 10 days.

Get the whole story by monitoring the birds in your garden

This is one chapter in the dramatic and fascinating story of the wildlife in your garden. Gain a richer understanding by participating in one of our citizen science projects, which contribute to conservation data.

  • Complete a 20-minute count of the birds in your garden every week with Garden BirdWatch, and find out how things change throughout the year supported by our passionate GBW team and community.
  • Monitor the bird nests in your garden or local area with Nesting Neighbours. Simply register the nest boxes or nests in your garden or local area and record what’s inside at regular intervals during the breeding season.

For the really curious among you, there’s also a wealth of information on our Blue Tit BirdFacts page.

Keep an eye out for other garden nesters

Great Tits breed slightly (approximately a week) earlier than Blue Tits, but the amount of time they spend incubating eggs and rearing chicks is very similar. 

Species that have multiple broods such as Robins and Blackbirds usually lay their first clutch in March.

If you have a nest box, early spring onwards is a good time to start carefully checking it for signs of breeding birds — you never know what you may find.

Need a nest box or bird house?

In order to monitor nests in your garden, you might need a nest box or two.

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