Who would have thought winter had a nasty sting in its tail?

After last week’s warm weather, the sudden rush of cold air from the Arctic — the “polar plume” — came as a shock, reminding us that we’re not out of the woods yet, even though the 1st of May is just days away.

One thing that amazes me is how newly-arrived summer visiting birds, such as warblers and swallows, can cope with a sudden, dramatic drop in temperatures which effectively plunges us back into winter.

Minus four centigrade was being forecast for Central Scotland on Sunday night and I wondered if the swallows and willow warblers that had been so obvious during the day would make it through the night.

In cold weather, swallows and martins flock over water where there is more insect activity, and on Monday the RSPB reported 250 swallows, 25 house martins and 25 sand martins at Aird Meadow, Lochwinnoch.

That other herald of spring, the cuckoo, is also back. Right on cue, they were being reported from the middle of the month, giving their distinctive, far-carrying call in and around Muirshiel Regional Park which has habitat ideally suited to these long distance migrants.

As I have mentioned here before, the British Trust for Ornithology have fitted satellite tracking devices to some cuckoos to unravel the mystery of where they go when they leave Britain in the autumn.

Results show they go to central Africa and spend the winter there before returning back to Britain in the spring.

The cuckoo has declined by 73% during the last twenty-five years. Scotland’s cuckoos are faring better, with the population stable or increasing slightly, while the decline is being felt greatest in England. The BTO research aims to find out why this is the case.

Dr Chris Hewson, the scientist leading the project at the BTO, said: “We know a lot about the behaviour of the cuckoo when it is here in the UK but our research has shown us that some of these birds spend as little as six weeks here, so it is vital to understand what pressures they face on the journeys to and from Africa and in the locations they spend the winter months.

“We can only do this using this cutting edge technology.” Meanwhile, I noticed two sandwich terns - also summer visiting birds - over Fairlie Bay in Monday evening’s hail showers. They feed on fish, so are not relying on a plentiful supply of insect food to see them through the cold snap.