The Wren is probably the most numerous and widespread bird in Britain, promoted to this exalted position after a long run of warm winters.  A prolonged period of snow and frost would soon reduce the population but, for the moment, Wrens are everywhere, and there are certainly plenty in our gardens.  These small brown bundles of feathers are not the most obvious of birds, scuttling amongst the rockery plants like feathery mice, in search of small insects and other scraps of food.  But when the males burst into song it is a completely different story.  How can something so small make such a huge amount of noise?

Wrens look bigger than they actually are because, unlike other contenders for the title of smallest bird in Britain, such as the Goldcrest, Wrens have a fluffy coating of feathers to cover their tiny bodies, providing excellent insulation.  In really cold winters, like the ones that we saw in the early sixties, up to two-thirds of Wrens may die.  Snow cover alone is not life-threatening as birds can feed or even roost underneath it.

When scientists working for the Thetford-based British Trust for Ornithology analysed the results of nearly one hundred years of bird ringing activity by trained volunteers, they found that British Wrens very rarely move anywhere.  However, Wrens elsewhere in Europe travel long distances to escape the winter cold and occasionally ringed birds from as far away as Russia do turn up in Britain.  It is hard to imagine how a bird that looks for all the world as if it is powered by an elastic band can manage to fly across the North Sea.

A male Wren has a very busy start to the breeding season.  When he is not singing his heart out to attract a mate and to defend his territory, he has to build several nests out of moss, leaves and grass, secreting them in dense, prickly vegetation.  The female then chooses the one that she likes, lines it with feathers and lays a clutch of five or six white eggs.  Inside the domed nest she will incubate the eggs for two weeks and then both parents will supply the chicks with insect-food for the next sixteen days.  The pair will probably have two or three broods between late March and early August, using a different nest for each breeding attempt.

Wrens do not live very long.  According to BirdFacts, the BTO’s online encyclopaedia about Britain’s birds (http://www.bto.org/birdfacts/index.htm), the typical life expectancy of a Wren is just two years and the maximum recorded lifespan is 6 years 8 months.  Only about one quarter of newly-fledged youngsters survive until the next breeding season and the chance of a parent bird being alive twelve months later is only one-third.  Given that these birds have such a short life expectation, it is not surprising that they approach the start of each new breeding season with a sense of urgency and a lot of noisy singing.