How to spot the signs of global warming in your back garden

Global warming doesn't only mean melting polar ice caps - it's changing the plants, birds and insects in your own back garden. Peter Marren reports

Spring is coming. Or is it? Many traditional signs of the new season have already appeared in the south of England. Trees are coming into leaf ever earlier. Animals and insects are emerging from hibernation in mid-winter. The grass is growing. And hands up everyone who used a lawnmower before mid-March last year (admittedly this year has been slower to get started).

What event defines the spring for you? Maybe it's the first primrose. Primroses traditionally appear around Mothering Sunday. But last year the countrywide average date for the first primrose was 28 February. And even in these climatically challenged times, February is not many people's idea of spring.

How about frogspawn? Well, if you live in Cornwall, frogs start to feel the urge around Christmas time. By the time spring comes to the south-west, garden ponds are full of tadpoles.