Thursday, 28 January 2016
One of the likeliest causes - though it can't be the only one - of sparrow decline is the sad loss of urban vegetation, as concrete, paving and decking take over (the insects that live on trees and shrubs are essential to the diet of growing sparrows). As Wellington is surely one of the lushest, greenest, most vegetation-rich cities in the world, the sparrows have nothing to fear on that score. Nor does Wellington have, as London does, a growing population of Sparrowhawks, raptors that live up to their name.
Despite sparrows' abundance, their cheerful sociability and their apparently perfect adaptation to urban life (see this story, sent to me by the excellent Dave Lull), they are far more vulnerable than they might seem. Such is their intense gregariousness that once numbers fall below a certain level, colonies seem to collectively lose the will to live; they virtually cease breeding and decline into rapid colony collapse - hence the speed with which they disappear from once sparrow-rich areas. It's a sad story - but, by the look of things, one that's not going to happen in Wellington.