Environment

Light pollution is causing spring to arrive a week early

Light pollution has another side-effect, it can push spring to emerge a week earlier in cities than in the country, a new study has found.

Trees were in bud an average of seven-and-a-half days earlier in well-lit areas than in dark spots. The early budding may cause problems for insects, which feed on leaves, and the birds which then feed on them in turn.

Sycamore, ash, oak and beech trees were all found to bud early under the influence of artificial light. Light had a more significant effect than temperature on when buds emerged, the scientists found.

Caterpillars are timed to hatch to make the most of opportunities to feed from freshly budded leaves, and birds hatch in time to feed off the young caterpillars. If this cascade effect is thrown out of sync, then wildlife is bound to suffer.

The amount of artificial light produced at night is growing by 6 per cent annually, the researchers say. Street lights have been found to confuse many species that prefer dark conditions, such as moths and bats.