City-dwelling creatures have learned to be sophisticated urbanites, according to researchers. As animals, like their human counterparts, are drawn to the bright lights and all its possibilities, so smarter city critters are emerging. While urbanisation may adversely affect some species, it is proving to be the making of others, scientists say.
From the city badgers who are heavier than their country cousins because they walk less, to hedgehogs and foxes who seem to have developed strategies for avoiding busy roads, the challenge of urban life is proving a minor obstacle. Even birds are getting in on the act, with sparrows weaving discarded cigarette butts into their nests and singing birds waiting till sundown when the din of traffic lessens.
Evidence is accumulating that city-dwelling animals frequently differ in behaviour relative to those from surrounding habitats, according to researchers at the Spanish National Research Council.
Contentiously, they suggest that successful urban creatures may be brighter and bigger-brained than their rural cousins. Experiments show increased learning propensity in city birds. Urban doves, for example, were less fearful of new things and were faster at learning than less urbanised doves.
Dr Rupert Marshall, an animal behavioural scientist at Aberystwyth University, has carried out a number of studies into birds and urban areas. He said: "This is a timely look at how man is affecting the behaviour of animals. Every month brings news of how another species is adapting to, or is affected by, man-made changes to its environment. Birds are found, for example, at higher densities in the suburbs because garden fences make ideal territory boundaries, and garden feeders mean they don't need a large territory to gather food.
"Of equal importance are the animals that appear unable to adapt. For example, while some birds sing at a higher pitch near noisy roads in rural areas, others are now found only where it's quiet."
Nocturnal ramblings hold few fears for this well-known forager. Terraced gardens have proved to be ideal feeding grounds, far from the peril of roads. They are especially attractive in the middle of the night when the threat of pet dogs is reduced and the hedgehog can concentrate on the important business of snaffling worms and beetles.
Traditionally shy and secretive creatures that favour nocturnal forays, they have been spotted feeding from urban fish ponds. The highly mobile creatures have been seen in smaller built-up environments such as town gardens, parks and churchyards across the UK, as well as in cities, including London, Bristol, Birmingham and Manchester.
Badger Bill, urban cousin of countryphile Brock, has embraced city life like a teenage raver. With a fast-food diet that includes chips, curries and cat food rather than the traditional earthworm, badgers have piled on the pounds – particularly as they exercise less: their roaming areas are a fraction of those of their rural relatives.
Streetwise squirrels adapt to urban noise by using their tails to signal trouble instead of barking. They are partial to city parks for food leftovers, which now provide more than a third of their diet; they love abandoned homes, which make perfect dreys.
These frequent flyers have quickly discovered the boundless opportunities of the modern cityscape. Urban street lighting lures insect life, providing bountiful feeding areas, and roofs proffer ample choice for secure and sheltered roosting.
Let it not be said the urban great tit is a dandy. Studies show some city-dwellers among this species are paler than their rural counterparts. The duller plumage is believed to be the result of a lack of carotenoids or natural pigments in city plants and other foodstuffs.
Noisy town life has changed this bird's tune, literally. The frequency of the bird song increases with the background noise. The average maximum frequency of the inner-city bird, where background noise levels average 66 decibels, is 3165Hz, compared with 2657Hz in the surrounding rural area where noise levels average 37 decibels.
The ultimate urban survivors. Street lights allow for round-the-clock dining and they've adopted snacking feeding habits. One study showed they can remember the faces of people who fed them and those who chased them away. When pursuers later tried to feed them, they were shunned – even after swapping clothes with the friendly feeder.
City-slicker foxes are in their element. They've found such rich pickings scavaging in the gardens and bins of suburban streets that they are more active during the day than their country relatives. They have also adapted other behaviours to urban life: studies show that city foxes are more likely to cross busy streets when traffic flows are lower.
The chirpy city sparrow is nothing if not resourceful. Many are now incorporating discarded cigarette ends into their nests to provide a warm cellulose lining for the family, as well as nicotine to ward off mites. Nests investigated by researchers had an average of eight butts. City sparrows also eat more often and have less fear of predators than their rural counterparts.