Urban Wildlife — Reading

Passage

A The assumption behind most conservation is that wild animals need distance from people, and that a city is therefore a place from which nature has been removed. The assumption is increasingly hard to defend. Peregrine falcons, which were close to extinction across much of the northern hemisphere in the 1960s, now nest on cathedrals and office blocks in dozens of cities, and in some regions urban pairs outnumber rural ones. Cities turn out to offer several things a peregrine values: tall vertical faces resembling cliffs, an abundant food supply in the form of feral pigeons, and an almost complete absence of the larger predators that take eggs and chicks. B What separates the animals that thrive from those that vanish is not size or diet but flexibility. Ecologists distinguish urban adapters, which exploit human environments while retaining wild behaviour, from urban avoiders, which cannot. Foxes, raccoons, crows and rats are adapters; specialists with narrow diets or particular nesting requirements are usually avoiders. Behavioural flexibility is the common factor, and it is measurable — studies comparing city and rural populations of the same species repeatedly find urban individuals solve novel problems faster and are quicker to approach unfamiliar objects. C Living alongside people also changes the animals themselves, sometimes rapidly. Urban blackbirds sing at higher frequencies than woodland blackbirds, because low-frequency song is masked by traffic noise. Several city bird populations now begin singing before dawn, apparently to be heard before the traffic starts. Urban great tits have been found to differ genetically from nearby rural populations in genes associated with exploratory behaviour. These are not adaptations over geological time; some have been documented within a few decades. D The consequences are not uniformly benign. Artificial light disrupts the navigation of migrating birds, and collisions with glass kill hundreds of millions annually in North America alone. Food subsidies from bins and deliberate feeding support unnaturally dense populations, which raises disease transmission. Urban animals show elevated stress hormones and, in several studies, shorter telomeres — a marker associated with faster biological ageing. A city can support a large population of a species while being a poor place for individual members of it. E Public attitudes are correspondingly divided, and the same animal is often both. Foxes are welcomed by some residents and regarded as vermin by others on the same street. Gulls that were coastal scavengers are now inland nuisances. Local authorities receive complaints and requests for protection about identical species, sometimes from adjacent addresses, which makes coherent policy unusually difficult. F Where design has been attempted, the effective measures are modest and specific. Patterned glass reduces bird collisions substantially and costs little when specified at construction. Wildlife corridors connecting fragmented green space matter more than the total area of that space, because isolated patches support fewer species than connected ones of the same size. Reducing lighting at migration peaks is cheap and demonstrably effective. Bin design, unglamorously, does more to manage urban foxes and gulls than any deterrent. G The broader implication is that conservation framed entirely around protecting places from people describes a shrinking share of the planet. More than half of humanity now lives in cities, and the animals that live there are not a curiosity at the edge of the subject. They are a substantial part of what remains, and increasingly the only wildlife most people will encounter directly. H Not every urban adapter is welcomed with the same enthusiasm, and the difference in reception says as much about human attitudes as about the animals themselves. Foxes and hedgehogs, both increasingly urban across much of Europe, tend to attract sympathetic coverage and dedicated charities. Urban gulls, pigeons and rats, arguably no less successful at adapting, attract organised culling programmes and headlines about infestation. Biologists who study urban wildlife point out that the ecological distinction between a 'pest' and an 'urban wildlife success story' is often close to arbitrary — both categories describe species that have found a reliable way to exploit human settlements — and that the difference in treatment tracks aesthetic and cultural associations more than any measurable difference in impact. Gulls that nest on roofs and take food from pedestrians are frequently more numerous, and arguably better adapted to city life, than the foxes celebrated in the same cities' nature documentaries. The distinction matters practically, because species labelled as pests receive active management aimed at reducing their numbers, while species labelled charismatic receive protection and public sympathy, regardless of which one is actually causing the greater ecological or practical disruption.

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