As I write, we’re in mid-March and experiencing perfectly seasonal conditions – blustery days that veer between sharp cold showers and warm spring-like spells of sunshine. It makes what went before all the more surreal. February ended with a week of full-on spring. The landscape was bathed in soft, hazy light and warm sun that tempted insects to emerge and birds to raise their voices to the blue sky. On Greenham Common, what I would usually regard as classic mid-March sightings were the highlights of a few-hour survey. Brimstones passed me frequently: animated scraps of such intense yellow-green that they are enough to persuade me hope yet remains in the world by sheer force of colour alone. In the woods on the edge of the common I saw two chiffchaffs working the tree-tops for insects. The woods shield a series of damp south-facing gullies, well-sheltered and probably harbouring plenty of winter gnats and midges for a wintering warbler. As I headed east back on the open common at noon, another unseen chiffchaff broke into full song – the earliest in the year I have ever heard one.
At dusk each day the spell was broken with the return of winter chill, a daily reminder that such conditions are far from normal for late winter. Perhaps the most outlandish statistic I saw during the warm spell was not the high temperature record (though this was impressive enough) but that under cloud cover a part of northwest Scotland did not drop below 16 degrees on the night of the 22nd. That would be a fairly normal daytime temperature in July in that part of the world, let alone an overnight minimum in February.
Did the unseasonable heat hint at a more dangerous fire to come? Similar weather patterns have certainly occurred in February before, though it is undoubtedly a rare event. Even under climate change we should not regularly expect these temperatures in winter. The greater threat to spring wildlife is not so much high temperatures triggering breeding cycles early but the possibility that the pendulum will swing quickly back to winter. More energy in the climate system means more variability, more extreme weather. Many have made the comparison between this year and late February / early March 2018 when we experienced consecutive subzero days, but it doesn’t take weather that extreme to wreak havoc. A few weeks of cool and damp will soon take its toll on newly emerged insects or snuff out early nesting attempts. Hopefully this spring will have just enough sunny spells to keep the early birds and bees going.