Have you seen a house martin calling in the early evening sun?

The sight of a swift swooping between the rooftops or the sound of a house martin calling in the early evening sunshine are often the first sign that summer is just round the corner.

However, this year an absence of house martin sightings has led to the RSPB receiving a high number of calls with people asking ‘where have our house martins gone?’

With their distinctive white rump and forked tail, house martins only grow 12cm in length and weigh no more than an AA battery. They are familiar to most people due to their habit of nesting on buildings, where they build unique nests made up of more than 1,000 beak-sized pellets of mud.

Every April, hundreds of thousands of house martins arrive back in the UK after an epic migration from sub-Sahara Africa, along with many other much-loved migrant birds such as swifts, swallows and chiffchaffs. This year it appears that numbers of house martins touching down in the UK has dropped, leading to a dip in sightings of the charismatic bird.

RSPB spokesperson said: “For many people across the country the sight and sound of a house martin is the first sign that the warmer summer weather is on the horizon. There are few better feelings than being able to sit outside on a warm evening with family and friends enjoying their dramatic aerial displays or their distinctive ‘jik jik’ call.

“However, a lack of sightings this year of the migrant bird have led to a rise in the number of calls from worried members of the public asking where all the house martins are. Despite what appears to be a dip in the number touching down this spring there are plenty of things we can do in our gardens to give those that do arrive a helping hand.”

There is still an element of mystery around house martin numbers in the UK but initial results suggest that between 2001-2011 the UK populations suffered a 16% decline.

It takes around 10 days for a pair of house martins to construct their mud-cup nest – where they’ll have two or even three broods over the summer – making it essential they find enough nest material.

They usually rely on gathering mud from the edges of water bodies or from muddy puddles on tracks and in farmyards, but recent and future dry weather could mean they are few and far between, so mad-made muddy patches will be important. By putting out wet mud in a shallow container like a dustbin lid, or creating damp mud at the edges of borders and ponds.

RSPB spokesperson added: “Without the right materials to make their nests it could affect their chances of breeding successful. So by creating just a small patch of mud at the side of your garden could make a real difference to a pair of house martins.”

House martins are one of a number of migrant birds that fly thousands of miles to nest and raise their young in the UK – other familiar faces you may see include swifts, swallows and chiffchaffs. There are many simple things we can all do in our gardens or outdoor spaces to help as they arrive, to find out more visit www.rspb.org.uk/birds-and-wildlife