A ‘circlage’ of circling house martins makes perfect sense

A FLOCK of small blue-black and white birds could hardly be described as a murmuration, a collective noun which is firmly owned by starlings.

Yet the swirling cloud of house martins I saw over the River Wharfe, near Barden Bridge, seemed to be micro-controlled by the same kind of telepathic force.

Clearly these house martins had just arrived en masse for the summer, and despite a chill northerly breeze they seemed to be finding enough small winged insects to replenish the body fat burned by the marathon flight from their sub-Saharan wintering grounds.

Thanks to the internet, I now know that the proper collective noun for house martins is a “circlage”, which makes perfect sense after watching about 40 of them flying in tight eddies at least 100 feet over the river, circling whilst somehow managing to avoid collision.

They were well above their brown and white siblings, sand martins, which I could see had also arrived for the summer and were already rocketing in and out of nesting holes in the riverbank or skimming myriad flies and midges from above the water.

This cloud of house martins will mostly disperse to find their own nesting sites – as the name suggests – on Dales houses as well as barns, churches and even the masonry of old bridges. This close relationship with humans and its fork tail has given it the widespread vernacular name of house swallow.

In the Craven area of North Yorkshire, it is known as the eaves swallow because eaves are where it often attaches its nesting “cup” of mud, sometimes attaching several to each other to form a sort of house martin apartment block.

Each one takes about 10 days to build, and an ornithologist once calculated that over 1,000 beakfuls of mud are required.

Shakespeare knew of the medieval belief that if the bird – then widely known as a martlet – chose your house to build its nest, then it brought those who lived there good luck.

In Macbeth, Banquo says: “Where they most breed and haunt, I have observed, the air is delicate.”

They also form colonies on cliffs, and the most famous in Yorkshire is on the limestone precipice of Malham Cove, where their cups of mud lined with feathers and dry grass are neatly tucked beneath overhanging rocks, and for years they have happily co-existed in close proximity to a pair of breeding peregrines.

The birds usually produce two broods before departing the UK in September and October.

Although it is believed they spend winters in the Sahel, south of the Sahara, a few years ago the British Trust for Ornithology stated: “Although over a thousand house martins are ringed in Britain each year, their wintering grounds remain a complete mystery.”

Relatively few of the two million birds which nest in Europe are seen in Africa, it seems, and because the birds are so small, satellite tags do not have sufficient battery power to track them. One theory is that they spend most of their winters feeding high above the African rainforests.