... Blue Tits (Cyanistes Caeruleus)
The milk bottle bandits
Blue tits have been on my mind lately as I had been hearing them singing loudly on my morning walks. However, in the last few weeks, I’ve been aware that they all seem to have gone silent!
I’ve discovered that this is because the need to attract mates has passed and we’re now into the peak of their nesting season here in the UK. We often have blue tits investigating an old nesting box in our garden at the beginning of the Spring, but sadly they’ve never decided to take up residence!
Only the female blue tit will build a nest, whether that is in a nest box or a more traditional crevice in wood or stone. Blue tits use grass to form a circular cup and then line it with moss and other soft materials, before laying between 8 and 10 eggs (although even larger clutches of up to 14 have been recorded in the UK). Once the eggs have hatched, both male and female spend every daylight hour hunting for caterpillars to feed the chicks.
What is in a name?
Blue tits are common across Europe and are seemingly one of the few British songbirds still thriving (they are listed as Green for conservation status). They've been resident here for thousands of years and have been mentioned in literature and historical records since at least the Middle Ages, although they sadly don’t seem to feature much in literature or poetry.
The Latin name for the blue tit is 'Cyanistes caerulus'. The 'Cyanistes' refers to the family of small birds to which they belong, whilst the 'caeruleus' means blue, to describe the bird's plumage. But how did 'cyanistes' become 'tit'?
Well, back in the time of the Norman Conquest, small birds like the blue tit were known as 'titmose'. Over time the 'mose' became 'mouse', and was gradually dropped to avoid confusion when referring to a bird!
‘Drawn to…’ is a series of short articles diving into the lives of the wildlife of the British Isles. From appearance and habits to their role in culture and folklore, these articles will always include some fascinating facts as well as some of my favourite sketches and illustrations!
Clever and community-focused
As a small bird, blue tits are in danger of predation from larger birds (jays and other corvids as well as sparrow hawks) as well as mammals such as weasels and stoats, rats, squirrels and, of course, cats. They've therefore developed a series of alarm-calls to warn others (including, very generously, birds of other species) about the presence of predators; there is a 'scolding' call to announce ground or low-flying predators, whilst an alarm-whistle warns of the proximity of sparrow hawks and other birds of prey.
Perhaps the very most interesting thing about blue tits, though, is their ability to transmit what they've learnt to other blue tits. If you're old enough to remember when doorstep milk deliveries were a common thing, you may well remember discovering that your milk bottles had been raided on the doorstep, with a carefully fashioned hole in the foil lid - evidence of a blue tit stealing the cream that separated to the top of the bottle of whole milk.
Door step milk deliveries became popular at the turn of the twentieth century - although in these early days, the bottles were delivered with no covering. Even with this advantage, only two species of British garden birds learnt to recognise a milk bottle and siphon off the cream - the robin and the blue tit - probably because birds are lactose intolerant by nature. However, both the robin and the blue tit actually developed a tolerance to lactose that is not present in any other bird so that they could make the most of the energy-dense cream without being ill - literal evolution in action!
After WWII, dairies began to top their milk bottles with a foil cap. This put paid to the robins' thievery, but not the blue tit - and once enough blue tits had learnt how to pierce the foil cap with their beaks, they somehow transmitted this knowledge so that ALL blue tits became proficient in breaking the cap!
And, of course, the collective noun for blue tits (or any group of tits) is a 'banditry'. Whilst this is probably down to their distinctive eye mask-style markings and their bandit-like foraging behaviours, surely their cream-stealing antics make it even more appropriate?!
Interestingly, whilst there has been a renaissance in recent years of doorstep milk deliveries, obviously enough people still aren't ordering full-fat milk for a new generation of blue tits to have learnt how to access the cream.
When is blue not blue, but violet?
One final fascinating fact about blue tits for you. Humans are unable to tell the difference between male and female blue tits as their colouring appears to be exactly the same. However, as with most birds, blue tits can actually see in the UV spectrum. To a female blue tit, a male’s blue cap will glow with a different intensity, which allows them to choose between potential mates!
If you’ve enjoyed this article and would like to support my writing, you can make a contribution via Buy me a coffee:
I’ve been working on this coloured pencil study of a blue tit with one of it’s young for a few months and it is finally finished! This artwork was created using Derwent Procolour pencils, a wax-based coloured pencil made in Cumbria, on to Bockingford Watercolour Paper, which is made on a traditional cylinder mould machine at St Cuthbert's Mill in Somerset. The artwork is available to purchase as a framed piece from my website.
Hi Ali, what a lovely piece of artwork. I adore blue tits, my next post is going to be all about them - I'll be sure to link to this post if you don't mind? The bit about the colouring is fascinating, and I'd completely forgotten about the milk tops! But I do remember that happening when I was a child.
I have a pair nesting outside my kitchen window, feeding babies as we speak 😍
I wonder if you move your nest box if they'll be persuaded to take up residence? Once they move in, they tend to come back.
How lovely, thank you for sharing. I am scolded by blue tits on an almost daily basis - especially when refilling my bird feeders!