The True Herald of Spring.

Many birders look forward to their first swallow sighting of the year as a moment to mark the arrival of spring but really the true herald should be the rather less showy and more discreet sand martin. The odd swallow can start to turn up at the end of March but the majority of swallows arrive with us around the second week onwards in April, whereas sand martins can arrive as early as mid-February. One good site to look for the early birds is over lakes and reservoirs feeding on the first flying insects to emerge on a late winter/early spring day.

Even though they are the smallest of our 3 hirundines their hardiness just seems astonishing as they battle with strong winds and low temperatures and then find enough of a food supply to keep going until warmer spring weather arrives. Sadly numbers did take a dramatic decline with a population crash in 1968-69 and 1983-4 due to a severe drought in the Sahel in Southern Sahara where sand martins spend the winter.

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You can also listen out for their buzzy, dry call, a rasping ‘chrrrp’ and a shorter ‘brrt’ call of alarm, its different to the more clear and chattering call of their house martin relatives. They even look more delicate on the wing than house martins or swallows, their flight is rather fluttering and jerky with flicking beats on long angled wings. The tail is short and only slightly forked. I also like to look for their distinctive brown breast band and lack of a white rump but on a grey, windy day with poor light conditions over Wilstone Reservoir its a real challenge to see !

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A vast sand martin colony . This one is in Buna village , Herzegovina in April.

As our sand martins arrive they need to join and re-establish a nesting colony and a nesting colony has several advantages with safety in numbers and more eyes to spot a predator with hobbies being their worst problem. Historically, sand martins nest in soft cliffs, river banks, maybe in soft banks over reservoirs but as these are becoming less available they will readily take to artificial nest sites set up on nature reserves, like the one on RSPB Saltholme in Middlesbrough. In spite of their rather delicate looks and tiny feet they are able to excavate a nesting burrow of 3 or 4 foot (sometimes longer) and even move stones heavier than themselves. They will make a minimal nest of grasses, leaves and maybe feathers at the end of their burrow to lay 3 or 4 white eggs, the young martins can fledge in 18/20 days. They usually have 2 broods and the young mature in a year and only weigh similar in size to a goldfinch.

Sand martin excavating a nest burrow.

Young sand martins almost ready to fledge.

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At the end of the nesting season, toward the end of summer in late August and into September, I like to watch for hirundine gatherings on roofs and telephone wires, they almost seem to gather to discuss the long journey they now have to make back to winter in Africa. Its a great moment to look for sand martins in the group and just marvel at this tiny miracle of migration.

Report by Colin Strudwick.