I was taking half an hour out from screen-sitting to do a little bit of digging of my new pond-to-be when all hell broke loose in the garden two doors down. The air filled with a raucous cawing as some Carrion Crows went crazy about something.

But it wasn't just a handful of them, which is the typical number I see in or from my garden. No, there were dozens of them.

This photo shows at least 27 (plus a Jackdaw on the right hand side). They were curtsying and flaring their tails and really going for it in a 'chorus' (I'm being kind!) of 'karrrr, karrrr, karrrr'. I estimated over 50 birds were involved in the commotion. If these were the All Blacks, then this was definitely something of a Haka.

Now if you saw this in the countryside you'd think these must be Rooks, for they are much more sociable birds, and of course they nest colonially (and will be busy nestbuilding in their rookeries right now).

But Rooks are a rarity over my garden (and never in it), and their cawing is subtly distinct - it is a less aggressive sound, more level in pitch, unlike the Crow's deeply downslurred and angry 'karrr', and the Crow tends to repeat the note three or four times in series which adds real emphasis to that sense that they're not best pleased.

Of course, with binoculars you'd see the subtle visual differences that tell these almost all-dark birds apart. Crows have black bills with little wedges of feathering on top of the nostrils, whereas Rooks have ivory-coloured bases to their bills extending as bare skin under their eyes, and no 'nasal' hair on top of their bills (at least in the adults).

A couple of photos at this point might help! Here is a Crow at my birdbath a couple of years ago...

...and a Rook outside my tent on a campsite in rural Devon, where big areas of open grassland and tilled land are much more its thing, allowing it to strut about, deep-probing with that bare bill for earthworms and leatherjackets.

...

So, what was my 'Crowd of Crows' up to and where had they come from?

Well, what we do know is that Crows in the UK, whether the Carrion Crow across most of England, Wales and southern Scotland or the Hooded Crow of northern Scotland and Northern Ireland, are very sedentary. So this is no migrant flock arriving from somewhere.

It is also the case that Crows are not total loners and will flock around good feeding sites such as estuaries and where farm animals are farmed intensively. They will also flock before going to roost, and first-year birds in particular are likely to gang together (most Crows won't breed until they are two years old).

So my best guess is that this is a group of local youngsters that are having a little wander around their local area. It is possible that they strayed into the territory of a resident pair (you can see their nest centre right in the tree) who started 'karrr'ing in protest, setting off the entire flock in excitement.

What I do know for sure is that after a good 20 minutes of furore, the melee dispersed, calm returned to the neighbourhood, and I haven't seen more than a couple of Crows from my garden since.

Of course it is Big Garden Birdwatch this weekend, in fact starting today, so what do we expect to see from your results for these birds? Well, in 2020, Carrion Crow came in at number 17, with an average of 0.6 birds recorded per garden, and sightings in 22% of gardens. In Northern Ireland, the Hooded Crow was 14th, with an average of 0.9 per garden.

It is actually the smaller Jackdaw, with its silvery head and white eye, that is the commonest of the three dark Corvids, seen in 20% of gardens overall, and commonest in Wales where it was seen in a third of all gardens.

The Rook, however, was only seen in 2% of gardens across the whole country, showing what a rare garden visitor it is in most parts.

Whichever you manage to see on your count, I hope you'll agree that, if you actually stop and look at them hard, and especially with a little sunshine to illuminate their feather gloss, they are actually very fine looking birds indeed.