22 Mar Early signs of spring becoming the new norm, says the Woodland Trust
Earlier signs of spring – such as the first leafing of trees or the first sightings of butterflies – could be here to stay says the Woodland Trust.
One of the first trees to come into leaf is the elder and for the last five years citizen science collected records of its first leafing have been earlier than the 20 year average by 4-16 days. 2024 seems to be following suit.
Observations of leafing on the likes of larch, rowan and oak have also been early – one to two weeks before the average. And there have been many sightings of brimstone butterflies already– traditionally one of the first to be spotted each year – about two weeks earlier than usual.
Dr Judith Garforth, Citizen Science Officer at the Woodland Trust, recorded elder first leaf on 20 Feb in North Yorkshire and said spring is spreading north rapidly.
She said: “Whilst the sighting of an elder In leaf was a very welcome glimmer of spring after all the grim wet weather, it was much earlier than I’d expect, especially this far north.
“Overall though, the general trend is continuing with spring arriving earlier and becoming something like the new norm. Our data provides the clearest evidence of a changing climate affecting wildlife.”
These early signs of spring are not a surprise this year since Met Office data* showed temperatures in February 2.2°C above the average, making it the warmest February on record for England and Wales. And the spring index, which compares modern and historic data is running 8.7 days earlier.***
Dr Garforth said earlier springs can lead to ecological food chains becoming ‘mismatched’ or out of sync.
For example, a study led by Malcolm Burgess** that used the Nature’s Calendar oak leafing data, showed that early oak leafing lead to an earlier peak in the number of moth caterpillars, which meant that blue tits needed to match their breeding timing so that their chicks were at their hungriest when caterpillar numbers were at their highest. However, the study found that the blue tits were able to react less quickly to the early spring temperatures compared to the trees and moths. This led to the timing of hungry chicks being later than the timing of peak caterpillar abundance, which in turn meant less food for the chicks, and therefore less food resources which leads to a decrease in breeding success.
Dr Garforth added:
“Another example is that we sometimes see insects emerging early in the spring before there are many flowers blooming to provide a good food source for them. Change has happened very quickly which is why the best option to help wildlife would be to slow it down– by reducing CO2 emissions and by planting more trees. We must continue to monitor this ever-important data we receive to keep tracking nature’s response.”
More volunteers are needed to become citizen scientists to keep this 300-year-old recording tradition alive. Go to naturescalendar.woodlandtrust.org.uk to find out more.
