AS far as I am concerned, summer has now started properly.

I’ve been waiting for the last of our migrant birds to turn up in Ryedale to spend the warm season with us, and they have finally made it.

These late arrivals are the much loved swifts and house martins, similar looking, but unrelated birds.

House martins are members of the swallow family and their cousins have been here a while.

Sand martins arrived first, returning to the banks of the Rivers Rye and Derwent in early April, with swallows making an appearance a week or so later.

I suspect that we like house martins so much because they choose to live cheek-by-jowl with us, constructing those distinctive semicircular, mud nests underneath our house eves or even inside deep window frames.

This habit has earned them the first half of their common name and the second half of their scientific name – Delichon urbica.

I actually like their French name best of all – hirondelle de fenetre translates as window swallow.

This seeking out of human company can only be a recent phenomenon in the grand evolutionary scale of things.

House martins have been around as a species for millions of years whereas human buildings made a first appearance a few thousand years ago at most.

This, of course, begs the obvious question, “Where did house martins build their nests before that?”

The simple answer is cliffs, and if you don’t believe me then just take a trip to the coast where you can see small numbers of house martins still favouring the old-fashioned nest sites, tucked under rock overhangs at Staithes, Sandsend and Bempton. Over in the Dales, Malham Cove has a famous colony as well.

Despite being late starters in the egg-laying stakes, most breeding

pairs of house martins still manage to raise two broods of chicks in a season.

They do this by taking advantage of the abundant insect life in high summer, enabling their chicks to grow quickly on a high protein diet.

In addition, they use an unusual, but very clever extended family technique; the grown-up chicks from the first brood help to feed and bring up their younger brothers and sisters in the second brood.

But that’s all to come. First the birds have to build a nest, or repair last year’s if it’s still there, and that might prove tricky at the moment.

House martins need a supply of mud relatively near the nest site which they collect a mouthful at a time, mix with a special gluey saliva and model into the desired shape.

Unfortunately, it’s been so dry recently that there is a distinct lack of muddy puddles around at the moment so the birds will really struggle to build anything at all.

If you know that there are martins in your vicinity you can really help by getting out the garden hose and creating the odd mud patch somewhere accessible.

Numbers of house martins are in serious decline all over the UK, and the British Trust for Ornithology is eager to find out why.

Despite being so familiar there’s a lot we don’t know about these birds, like whereabouts in Africa they go for the winter for example.

It is suspected that they spend most of their time feeding out of sight high above the Congo rainforest, but we simply don’t know.

The birds may be facing problems in Africa or it could be here in Britain, so the BTO is monitoring their nesting behaviour at home first.

If you have house martins nesting on your house, or one of your neighbour’s, and you would like to help, then have a look at and see if you fancy joining in.