THE saying ‘Birds of a feather flock together,’ like many such homilies, is often true but not exclusively so. Some avian species are particularly solitary by nature and don’t flock at all; robins, for instance, are so intensely territorial that they cannot abide the proximity of another redbreast except for their mate and even then only during the brief spring breeding season.

Other birds actively seek each other’s company during the breeding season and nest colonially. Steep sand-banks on both the River Rye and the Derwent have numerous sand martins nesting in burrows, cheek by jowl with each other.

It could be argued that this apparent sociability is just an accidental consequence of there being very few suitable sandy banks available, but the same certainly can’t be said for our house martins. Even when there are scores of perfectly good house eaves to choose from they will invariably opt to share the same house with other pairs of house martins.

As a general rule though, flocking is not a common phenomenon for British birds in the summer months as most species seem to prefer a bit of privacy when bringing up a nest full of chicks.

More to the point, they like to jealously guard a bit of territory containing the family’s food supply and will aggressively keep interlopers out.

This time of year is a different kettle of fish though, and many species of birds will form winter flocks, sometimes even with a mix of different types of bird making up the crowd.

Jackdaws and rooks are often seen feeding together in large mobs on farmers’ winter stubble fields and finches will do the same thing - chaffinches, bramblings, greenfinches and goldfinches all foraging for seeds together.

In woodlands it’s members of the tit family that get together for feeding, often joined by goldcrests and treecreepers; the whole loose flock of individuals will move through the bare forest canopy together, hoovering up stray seeds and insects as they go.

The fact that birds form flocks in winter has been known for as long as our ancestors have been hunting them but what still baffles ornithologists is why they do it.

One theory is that, when feeding, lots of eyes are more likely to find the food even if it means having to share it and, to quote another

famous saying, ‘There’s safety in numbers’. Its thought that any individual bird is less likely to be picked off by a predator if it is part of a big group than if it was on its own.

As for what is the most impressive example of winter bird flocking on display, there is only one real candidate - the humble starling.

In certain locations around the UK these birds congregate at dusk in enormous numbers to roost, probably to share body-heat in cold weather but also to exchange information about local food supplies.

But it’s what they do just before they settle down to sleep that is astonishing.

I was lucky enough to witness a ‘murmuration’ as it’s called at the end of November near Gretna in the Scottish Borders.

An already large flock of starlings we had spotted swirling against the orange evening sky was joined, every twenty seconds or so, by newly arriving smaller groups several hundred strong until the main flock probably numbered about 20 thousand starlings.

We watched entranced as this huge mass of birds then twisted, cavorted, expanded, contracted and tumbled across the sky - changing shape like the bubbles in a 1970s lava lamp.

After a 10 or 15 minute display the flock finally spiralled downwards to the very trees we were stood next to with the noise of a dozen large waterfalls as we gawped open-mouthed at the scene.

Unfortunately, we don’t have any murmurations on this scale near Ryedale but Whitby and Scarborough town centres both have impressive ones involving a few thousand birds and well worth a late afternoon trip to see.