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Disturbance in January

by Juliet Hawkins

You probably don’t think of January as being a month of disturbance if you’re a birder unless someone walks by with a dog disturbing the bird or flock you’ve got your binoculars trained on, or a farmer trying to disturb the pigeons or geese on emerging crops.  But I’ve just returned from a walk feeling terribly guilty.  I didn’t mean to disturb anything but I did.  And it wasn’t a bird..

You see I went on a woodlouse identification course and wanting to put what I learnt to good practise, I pulled at a rather small strip of moss-covered bark of an old fallen oak tree trunk.  I was disappointed to find no lurking woodlice but then horrified to see a sleeping fat green caterpillar curled up in a knotty recess of the underside of the bark.  Despite the urge to pop it into a plastic specimen tube (meant for an unsuspecting woodlouse), and take it home to identify from my big glossy moth caterpillar book, I desperately tried to return the caterpillar, in recess, back to where I had stripped it from.  And then cover it with a bit more bark.  But as I did so I pulled off another bit of bark and under that was a very hairy curled up brown caterpillar.  Aaagh!  After considerable patching up I beat a hasty retreat and considered what else I might be disturbing unintentionally.

The likelihood of disturbing great crested and smooth newts and grass snakes in our big log pile is quite high so we have to ensure we never get near the ground layer.  And we take care not to touch the huge jasmine plant in the greenhouse as the hedgehog likes hibernating in the base.  Whilst the winter might seem an obvious time to repair the farm buildings, our seven species of bats are extremely sensitive to disturbance and if woken during hibernation their winter waking pattern is upset and can lead to using up their fat reserves quicker, threatening their survival.  But this winter, my clumsy actions are nothing compared to the effects of climate change on wildlife - worldwide.

Red Admiral and Brown Hare
Red Admiral and Brown Hare both acting as if spring is here.

I have just been emailed a photograph of a juvenile great crested newt eating a slug – they don’t usually emerge until February or March when the temperature warms up. On New Year’s Day red admiral butterflies were seen down the road and last week I saw brown hares very interested in each other!  Long term records indicate that in spring we are now seeing the timing of a wide range of natural events including flowering, insect emergence, tree leafing, summer migrant arrival, bird nesting and amphibian activity happening between one to three weeks earlier than 30 years ago.  This might not be a problem on its own, but there are differing response rates between different species suggesting mis-matched spring responses which may affect species survival - or extinction. Thus if birds nest earlier but the larvae on which their chicks depend hatch out later, the chicks will starve.

Disturbance caused by global warming is going to affect those caterpillars in the bark considerably more in the long term than my lifting the bark ... I need to be far more worried about my everyday activities that result in CO2 emissions - and start working responsibly towards reducing them.

Juliet Hawkins is a farm conservation consultant involved in conservation projects on her family-owned farm.