A Coal Tit’s winter food cache

January 21st 2019

Article originally published, without images, in Am Bratach No. 327 January 2019

There is not a breath of wind but the cold fingers of winter reach into my very core. I can even taste the freezing air in my lungs. Everything is still except the high pitch calls of small birds deep in the Culag woods. I can make out blue tits, great tits, coal tits ducking and diving amongst the birch bark and ivy. A treecreeper makes its way up a gnarled alder tree; long tailed tits repeatedly call to each other as they do acrobatics in the tree tops. I watch them flit cross my path and count them one by one. These dainty birds with their absurdly long tails are one of my favourites. Even Europe’s tiniest bird is here. Some Goldcrests arrive in Scotland from Scandinavia just for the winter, some battling through the 400-mile North Sea crossing in less than 24 hours.

A band of coal tits, their subtle winter-coloured plumage a perfect match for the surrounding environment, gather on a tall Scot’s pine tree. The birds rummage within the needles for insect food, so delicate is their fidgety but precise work. Coal tits have long toes and an extremely narrow bill, the former ideal for acrobatics high in branches. In the otherwise motionless valley, all these small spirits kindle the life of the land.

In the winter, blue tits often go about in these mixed species flocks; indeed they often form the nucleus of such aggregations. Ringing studies have shown that blue tits come from two different social backgrounds: some are residents, moving around with the flock close to their territory or birthplace; others are nomads, moving from area to area and enjoying only temporary membership of any flock. I wonder where these blue tits have come from. 

By grouping together and going systematically through a woodland, birds can save a lot of wasted time and energy searching a patch that has just been searched thoroughly by their neighbour. It makes sense to cooperate. And of course it is a delight when you suddenly come across one of these mixed species flocks of woodland gymnasts.

Anyone who spends a lot of time walking in the winter quickly realises, that contrary to common perception, there can be a lot of birds in some of these tiny pieces of woodland, even in the coldest months. Birds need adequate food sources to stay safe and warm through the long cold season, but when there are no buds, fruits or flowers available, plants are dormant and insects are scarce, what do winter birds eat? While there may not be flying insects in the winter, dormant insects and larvae are a critical food source for birds. Tits, robins, wrens, treecreepers, woodpeckers and other birds will forage in tree bark for insects that provide valuable protein.

But finding enough food can be a challenge, especially in poor weather and harsh conditions. That is why some clever birds have been “caching” food throughout late summer and autumn.  They will visit these extra food supplies all winter long. Birds have good memories and can recall where they found exceptional food sources earlier in the year or in previous winters, and they will often revisit the same areas in search of more resources.

There is one delightful little bird that does this caching business really well. For a coal tit, life can be hard. Being much smaller, coal tits are constantly bullied by blue tits and great tits, which frequently attack them and steal their food.  Where they all live together, coal tits will find themselves literally at the bottom of the tree when it comes to nest sites. Blue or great tits take the safer, higher holes, while coal tits are condemned to mouse holes and crevices among roots.

But coal tits are clever. When a while coal tit finds a suitable supply of, let’s say, sunflower seeds in a nice persons garden, handily available  in a lovely hanging tube feeder, it will take a seed, hide it somewhere such as a crevice in tree bark, then return time-after-time to do the same thing. When blue tits, great tits and house sparrows are fighting among themselves for a dominant spot on the feeder so they can munch away, a coal tit will nip in as quick as lightening, carry out a short commando-style raid, and grab a seed for it’s food cache.

Indeed, a small flock of coal tits can empty a whole feeder of black sunflower seeds in less than a day doing just this. And if you didn’t know that the birds were caching the food rather than eating it (though they will of course be eating some in the process to keep energy levels up), then you might be forgiven for thinking that hundreds of them were involved in the sortie on the feeder, rather than the more probable number of half a dozen.

As part of this caching strategy, individual coal tits will use multiple locations to hoard their winter supply of food. This is called ‘scatter hoarding’. This ensures that if another species of bird – e.g. the more dominant Great Tit – finds the food cache, then it will lose only one or two. 

Just as the small birds in winter flock together to improve their chances of finding food and surviving attacks by predators. I like to think that as we prepare ourselves for the weather and times ahead we can follow their example.

Andy Summers

Senior Countryside Ranger for North Highlands                                

High Life Highland Ranger Service

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