by Matthew Cobb
Western Europe is being affected by a substantial decline in many species of songbirds. Two of the most common birds of my childhood – sparrows and starlings – have seen massive population crashes. Both species are closely linked with humans. Sparrows used to live in the eaves of houses, and were the symbol of working-class London (people would be described as “a chirpy Cockney sparrer”). Starlings used to blacken the skies of many cities with dusk displays of swirling hallucinogenic patterns. They are now largely limited to a few rural outposts (see below):
Why are they declining? The Royal Society for the Protection of Birds has understandably been preoccupied by this. Together with the RSPB, a group based at Leicester Univeristy has been trying to find out why the sparrows are disappering. Cats do not seem to be responsible. The data suggest a number of factors are involved – low ambient temperatures, extremes of rainfall, low aphid densities leading to high levels of vegetable matter in the birds’ diet, and high concentrations of air pollution from traffic. All these factors suggest that what’s actually causing the population to decline is the lack of insects. The British have bombarded their gardens and their fields with insecticides; the birds are suffering now, but decline in insect numbers could have a series of disastrous effects on plants and other wildlife.
The history of the USA shows the dangers. In the 19th century the Passenger Pigeon (Ectopistes migratorius) was present in such numbers that flocks numbered billions of birds and would take hours to pass overhead. For complex reasons that are still debated (habitat loss, disease, predation and hunting are some of the factors involved) the population size plummeted and Martha, the last known Passenger Pigeon, died a lonely death in Cincinatti Zoo.
British songbirds could face a similar fate. And, as the saying goes, extinction is forever.
To find out more, read this article from Animal Conservation about the decline of British sparrows (you or your institution will need a subscription to get past the abstract).
One thing that the RSPB may be overlooking is the quality of gardens. Aside from pesticides, the fashion for paving gardens, turning them into patios or installing decking may have something to do with this decline.
I can tell you precisely what has caused a decline in these two species of birds around my house – me! I had six vent holes in the attic of my house; and each was occupied by a nesting starling or sparrow. I fenced them off with quarter-inch steel mesh. Let them go nest where ever starlings and sparrows nested before there were human homes with attics and vents. On the other hand, if you really want to see more of them; just make a few unobstructed vent holes into your own attic. Don’t forget to take out extra fire insurance (heater, stove, and dryer vents are the bird’s favorites), and you might even decide to study lice as you won’t have to leave home to collect specimens.
It’s a shame there isn’t some feasible way to capture European sparrows and starlings that are over-running the U.S. and release them back into their native habitat. Seems that would be a win-win situation for native bird populations in both hemispheres.
As an aside, I’m living in Naples, Italy right now, and all I ever see are sparrows. Well, now that it’s spring we’re overrun with swifts and swallows, but who’s complaining about that?
This is a bit of a nitpick, but the spelling should be “Cincinnati” rather than “Cincinatti”.