Rise of the synanthropes

Synanthropes: wild animals that live near and benefit from humans. An exploration of why some species thrive among us, and how urban planners are managing their increasing numbers. 
  • A raccoon peers out from behind foliage in Toronto. The masked bandits have successfully colonized our cities, and not everyone is happy about it. (Photo: Vladislav Kamenski/Can Geo Photo Club)

At 2 a.m. on a humid Vancouver night, Jim Sutherland and his wife, Jessie, are jolted from their sleep by strange noises coming from the ground floor. Taking a baseball bat in hand, Jim creeps down the stairs and into the kitchen, where he’s shocked to encounter a pair of masked bandits — two raccoons have deftly removed a container filled with cat food from a kitchen cupboard and are now trying to drag their pilfered prize out through the cat door. “The food jar was round and the door was too small, so they were having a problem,” recalls Sutherland.

Few animals possess the boldness and dexterity to attempt such an act of thievery, but the raccoon qualifies on both counts. Since the early 20th century, when they began appearing in metropolitan areas, raccoons have become North America’s most abundant and widespread urban transplant. Remarkable climbing skills, a diverse diet, a nocturnal lifestyle and keen intelligence have enabled them to make a smooth transition to city living.

But while raccoons may be the wild creature most familiar to urban dwellers, they’re certainly not alone. Coyotes, beavers, red foxes, striped skunks, deer, river otters, harbour seals, crows, peregrine falcons, bald eagles and Canada geese also inhabit our cities. In some places, black bears and mountain lions are even becoming increasingly visible.

The phenomenon of wild animals adapting to, and even benefitting from, urban living has become a global issue, with cities experiencing such diverse challenges as feral dogs riding Moscow’s subway to wild boars uprooting soccer pitches in Berlin. It has become so commonplace that scientists have coined a term to describe the trend: synurbanization.

It’s a subject of growing academic interest because it shows how fast certain wild species (known as synanthropes) can adapt their behaviour and physiology to outside pressures, a process that some scientists describe as microevolution. Many researchers now believe that cities could actually be causing rapid evolutionary changes in wildlife that normally take centuries to occur.

“We have this view of the wild as a pristine place and of evolution as something that happens in the wild. But humans in cities are changing the animals now,” says Suzanne MacDonald, a psychologist and biologist at Toronto’s York University whose studies of urban raccoons have led her to theorize that the demands of the urban habitat are creating a type of “uber raccoon” that is more intelligent and resourceful than its country cousins.

The main driver of wildlife from backcountry to downtown is urban sprawl. In Canada in 1911, for instance, 45 per cent of the population lived in an urban area; a century later, 81 per cent did. A similar country-to-city shift occurred in the United States during the same period. As cities expand, natural habitats are being consumed. This sprawl has proved damaging for some animals, but others have profited from an environment that supplies plentiful sources of food, warmth and protection from predators.

This emerging population of wild animals is creating new challenges for wildlife managers and urban planners, who must find a balance between the needs of these creatures and the desires of citizens. 

People either see wildlife in cities as the Disney ideal or as a menace.

In Toronto, researchers from the University of Toronto and York University are collaborating on a five-year study entitled “Crossing Boundaries: Encounters with Urban Wildlife in the GTA” that hopes to foster an understanding of cities as wild spaces.

Sue Ruddick, a University of Toronto geography professor and one of the principal researchers, says the boundaries in the title refer both to the idea of wild animals crossing city lines and to the need for us to think in new ways. “Too often when people talk about greening the city, they neglect to take animals into account,” says Ruddick, who recently organized a conference on “habitecture,” which she describes as “the conscious design of architecture and infrastructure with animals in mind.”

Ruddick believes the debate over urban wildlife in Toronto often features highly polarized attitudes — “people either see it as the Disney ideal or as a menace.” That clash of attitudes was highlighted during Toronto’s recent “war on raccoons,” a conflict that gathered momentum after it became apparent that the wily bandits had no trouble vandalizing the city’s green bins for organic waste.

Passions came to a head in a 2011 court case involving a man who attacked some baby raccoons with a shovel, killing one. The man blamed the cubs for destroying his garden. Half of the citizenry vilified the assailant, while equal numbers defended his actions and called for a euthanization program.

The city’s solution was to replace all its green bins with a raccoon-proof design at a stunning cost of $31 million over 10 years. When the bins were unveiled at a 2015 media conference, Toronto mayor John Tory boasted, “We have left no stone unturned in our fight against the Raccoon Nation. Defeat is not an option.” 

Whether or not it was tongue in cheek, this kind of talk fails to acknowledge that any attempt to rid the city of raccoons would be as futile as trying to dig a hole in the sea. Suzanne MacDonald’s research with radio collars and night-vision cameras has revealed how many raccoons inhabit the raccoon capital of the world. “I’ve seen backyards with 50 rac-
coons in them,” she says, pointing out that each raccoon has a surprisingly compact home range of three square blocks
and within that area may maintain 10 den sites. “They don’t cross major roads, so where they’re born, they live. They find all the food they need here, and it’s where they eventually die.” 

A coyote surveys a field in suburban east Ottawa. Coyotes have colonized virtually every city in North America and have even been known to thrive amid high-rise apartment complexes and industrial parks. (Photo: David White/Can Geo Photo Club)

Yet while raccoons may appear mildly threatening, they don’t trigger the same sort of atavistic fears as the coyote, a true survivor that has overcome government-sponsored killing programs in the United States and Canada that slaughtered millions of the animals.

Today coyotes have colonized virtually every city in North America and are surviving even in downtown sections, as demonstrated by Ohio State University wildlife biologist Stan Gehrt. He and his team began tracking coyotes in the greater Chicago area in 2000, capturing and placing radio collars on close to 700 coyotes, with 50 or 60 being tracked at any one time. Gehrt believes it’s crucial to understand how these carnivores interact with the urban terrain, both to figure out how to best manage them and to avoid conflict with people.

Night-vision cameras have revealed just how adept these canids are at remaining invisible as they navigate the urban grid. “They routinely pass by people on the streets within a few metres without anyone noticing them,” marvels Gehrt.

When he started his research, Gehrt assumed that coyotes would be found in only the more remote suburban areas. He has since discovered that some live in the most urbanized sections — in city parks, amid apartment complexes and in industrial developments. “We constantly underestimate their abilities,” he says, noting that urban coyotes may range over as much as 40 square kilometres in one evening.

Wildlife managers certainly underestimated what they were up against when the first wave of coyotes began slipping into Vancouver in the 1980s. A plan to capture the animals by luring them into traps with raw meat was hatched. Officials confidently predicted they would have all the invaders rounded up within three weeks. They failed to catch a single coyote.

Although human conflicts with aggressive coyotes often receive major news coverage, such incidents are rare, and when they do occur it’s almost always because people are feeding them, insists John Gray, manager of animal control for the City of Vancouver and a director of Vancouver’s Stanley Park Ecology Society, which runs a coyote awareness program.

Calgary operates a similar program, whose design was influenced by a study of its coyote population headed up by Shelley Alexander, a geography professor at the University of Calgary. Among the questions Alexander tried to answer was how much of an urban coyote’s diet was actually composed of neighbourhood pets, a red-flag issue for many homeowners. After examining 500 scat samples, Alexander says traces of pets were found in just six samples.

Those results mirror the numbers that Gehrt’s teams have reported, where analysis of more than 1,400 coyote scats found that the most common food items were small rodents (42 per cent), fruit (23 per cent), deer (22 per cent) and rabbit (18 per cent). Only 1.3 per cent contained evidence of cats. 

Studies have shown that when woodlands are converted to suburbs, the crow population rises by 300 per cent because manicured lawns and high, leafy trees are a crow’s ideal habitat. (Photo: Jim Walling/Can Geo Photo Club)

Crows are one of the better-known species that have migrated into urban areas, growing fat on our discarded french fries and honing their street smarts by memorizing the routes of garbage trucks. But other avians are also adapting.

Urban-dwelling peregrine falcons have become more nocturnal in their habits, using artificial lights to hunt night-flying birds and bats. In another oddity, two types of city songbirds — the house finch and the house sparrow — pack their nests with scavenged cigarette butts (as many as 40 per nest) to protect their young from harmful mites. The birds seem to instinctively know that the chemicals in nicotine repel parasites.

Noise is also driving change in the songs of city birds. Studies have confirmed that male songbirds from several species modify their warblings in response to the din of traffic. Stefanie LaZerte, a post-doctoral researcher at the University of Northern British Columbia, recently completed a study in which she discovered that when confronted with a recording of traffic noise, black-capped chickadees in the city would quickly shift their song to a higher pitch to make it heard over the lower register rumble.

“We know the birds are adjusting, which is good,” says LaZerte, “but we don’t know what effect this compromise may have on mating or how effective the higher frequency songs actually are. There are still many questions to be answered.”

What do birds that thrive in cities have in common? According to the latest research, they are bolder, healthier and brighter. A 2011 study of 82 different species in 12 cities in France and Switzerland determined that the one key similarity among birds that had made successful adaptation to urban life is larger brain size in relation to body size. The researchers concluded that some smaller-brained species, such as buntings, warblers, orioles and flycatchers, may disappear from cities unless efforts are made to create patches of their original habitat. 

At the same time, cities also retain much more avian diversity than previously believed. According to the first-ever global study of biodiversity in urban areas, published in Proceedings of the Royal Society B in 2014, at least 2,041 species live in the world’s cities. The list includes nearly 75 per cent of all bird families, including 36 species threatened with extinction. 

The truth is that we have to deal with these creatures because they aren’t going anywhere and may even increase in numbers.

High on the list of the challenges facing urban ecologists and city planners is mitigating human-animal conflict, which is complicated by the fact that many urban residents are less familiar with wildlife than their counterparts were 30 years ago. In his book Nature Wars: The Incredible Story of How Wildlife Comebacks Turned Backyards into Battlegrounds, author Jim Sterba argues that a detached, unrealistic view of nature leaves city dwellers ill-equipped to deal with the management issues posed by flourishing urban wildlife populations.

Ill-equipped or not, the truth is that we have to deal with these creatures because they aren’t going anywhere and may even increase in numbers. Not only do urbanized crows live longer, they need only one-tenth of the territory they require in the wild. Studies have shown that when woodlands are converted to suburbs, the crow population rises by 300 per cent because manicured lawns and high, leafy trees are a crow’s ideal habitat. Accelerated growth rate has also been charted for coyotes because the pup survival rate in cities is five times higher than the rate for rural cubs. 

And the problem of urban wildlife is getting bigger, literally. Gehrt, the Chicago researcher, suggests that urban coyotes may be setting the stage for their larger brethren — bears, wolves and mountain lions — to start drifting into cities. “Basically, it’s an uncontrolled experiment,” he says. The arrival of larger beasts is already happening in the Vancouver area, where black bear sightings are on the rise. 

Mike McIntosh, a veteran wildlife ranger with the Vancouver Park Board, believes that cities must develop new methods of integrating the natural world into the urban jungle. He is convinced we have an innate need for animals in our lives and that how we cope with urban wildlife is simply a microcosm of how we deal with nature around the planet. “We have to find ways to live in harmony with wildlife,” he says. “Not just the elephants in Africa, but also the raccoons in your backyard.”

Related: How wildlife use human infrastructure to help with the hunt