The purple world of the blackcap

Photograph of a bird being released after ringing, taken by Simon Lane (Pennicott)

September and October is the peak period for blackcaps passing through gardens and along straggly hedgerows – which landowners will hopefully leave intact for as long as possible so the birds and insects can make full use of the food they contain. How do I know this? Well, I could refer to the scientists at the BTO who spend their time studying birds but, as we all know, we’re tired of experts. It’s easier to observe that other icon of modern Britain, the shiny car on the drive – or even the washing line.

Just as the scientists now track the movements of birds in much the same way Tesco tracks its trollies, by fitting them with a tag that is picked up by a receiver as they fly over it on key migration routes, savvy non-expert Brits can track them by searching the droppings on their car for the tell-tale purple deposits of blackcaps. This species is now one of our commonest summer birds, their loud song provides the background to spring’s dawn chorus and continues into mid-summer as they have several broods when breeding conditions are good.

They are also migrants. For eons they have bred in northern and central Europe taking advantage of the longer daylight hours to gather their insect prey, migrating back to the Mediterranean climate of Iberia and north Africa for the winter. However, some of them now stay in Britain for winter (climate warming) and some of the central European population too now come here to take a chance on our increasingly mild climate and the abundance of food available during short winter days (garden bird feeders).

This avian commuting is fuelled by berries – principally elder and bramble – hence their dependence on untidy hedges and patches of scrub. When these are exhausted the inconspicuous, but hugely important for wildlife, ivy berries come into their own. 

So why not take a break from regular car-washing, strictly in the interests of science of course, by allowing the droppings to accumulate. Sit back, relax, then check on the proportion of purple amongst them. Marden’s own Archimedes – but in an armchair, not a bath.