Read Online Feral Cities by Tristan Donovan - Free Book Online Page B

Britain’s Royal Society for the Protection of Birds is one of the people trying to solve the Great Sparrow Mystery. “Quite often if a familiar bird declines, there’s a glut of research projects and you will come up with a plausible explanation fairly quickly,” he tells me from the organization’s headquarters, a lodge house nestled within a nature reserve deep in the Bedfordshire countryside. “It’s fair to say that with urban sparrows we’ve had that initial buzz of activity and, so far, it’s still a bit of a mystery.”
    There is no shortage of theories. Although they eat bread, dog food, and other scraps, sparrows are seed eaters at heart, so some suggested a lack of seed was the problem. But when the theory was tested by supplying seed to the birds year-round, it made no difference.
    A lack of the invertebrates that young sparrows are reared on was another explanation. “Where sparrows don’t have enough insects they tend to feed their young with bread and peanuts and rubbish like that, and usually you’ll see high rates of chick mortality in situations like that,” says Will. But when Will and his team tried dishing out juicy mealworms to London’s sparrows, it only helped the smaller colonies and did little to aid larger gatherings of the birds.
    Others pointed the finger at pet cats and sparrowhawks. Yet cat ownership in London has changed little in the past twenty years, and studies suggest that cats kill more blackbirds than sparrows anyhow.
    The case against sparrowhawks seems more convincing. These small birds of prey, which feed on a variety of birds (not justsparrows), are making a comeback in British cities after being almost wiped out by the notorious pesticide DDT. But although sparrow numbers are lower in urban gardens where sparrowhawks are active, that could simply be because sparrows avoid the area or evade capture by hiding in dense vegetation. Equally, there are plenty of places where sparrows and sparrowhawks live side by side, suggesting that sparrowhawks simply don’t eat enough sparrows to be the sole cause of the decline.
    Wilder theories have also been floated. Some suggested that electromagnetic radiation from cell phone masts could be affecting the birds since there are fewer sparrows in places where there are more masts. But, says Will, these are “also the highly urbanized places where you might expect to see fewer sparrows anyway.”
    Maybe it’s genetic, others suggested. Since sparrows don’t travel far, there’s little mixing of urban and rural populations of the birds, and city sparrows do have slightly less genetic variation than their country cousins. Trouble is no one knows what, if any, difference that makes.
    Architectural changes are a better culprit. Buildings define the urban landscape and have a major bearing on what can and cannot thrive within cities. This theory is supported by a study that looked at how sparrows fare in different areas within English cities. It found that poorer neighborhoods offered more suitable habitat for the birds than the better-off areas. So in Golborne, one of the most deprived wards in London, where the brutalist concrete of Trellick Tower looms over high-crime streets, sparrows should do well. Yet three miles south in Queen’s Gate, home to Harrods and the city’s super-rich, the sparrow should be a rarer sight.
    Like starlings, sparrows have their own architectural preferences. They like houses built before 1945 best—and the more run-down they are the better, because that means there are more holes to nest in. Newer buildings are less welcoming, offering fewer nooks and crannies for nesting. Richer areas also have housing in a better state of repair, and house sparrows are less commonin areas where houses have been renovated in the past decade. “If you replace your rotting, wooden soffit boards with PVC, which a lot of people do, the sparrows are