Feral Cities (26 page)

Also, their frontal vision seems to be about helping them accurately target nearby objects with their beaks rather than seeing what lies ahead. Instead, their sideways vision does most of the work in detecting their surroundings. Even then, the way they perceive the world during flight is more about spotting movement than detail. When in flight birds are looking for predators, prey, food, other members of their flock, and potential nesting sites, and as such when they are draw into cities by the lights they aren't looking ahead but to the sides.

Migrating birds are also flying fast because they have a long way to go and it is much harder to keep flying slowly, and since they are flying high they don't expect to bump into anything. It's like driving fast with poor brakes along a highway that you assume will be empty, while looking out the side window for interesting things and using the corner of your eye now and again to see what's ahead. In that situation it would be no surprise if you collided with a large obstacle in the road.

And this seems to explain why everyday urban birds, like pigeons, are so much better at making their way around built-up areas. They move slower, know the area, and expect to encounter obstacles. “Pigeons are local birds,” says Graham. “They know where they are and get to know their patch. A new bird coming into an area could easily get disorientated and crash into something. Even so, I still get green finches, house sparrows, and pigeons flying into the window where I live, but that's probably when they are spooked by a sparrowhawk or something like that and think they are flying into cover when it's actually the reflection of the cover behind them.”

For bats the problem is different, although the reasons why they crash into buildings are less well understood. Two theories exist, says Annette. First is that they mainly use their echolocation abilities when hunting and don't use it when migrating because they don't think it's needed. The other theory is that the urban surfaces distort their echolocation calls just as they mess with bird song, resulting in a fuzzy picture of the world around them and increasing the chances of them flying into something.

By the end of my morning with the collision monitors they have filled four cars with bags of birds piled up in boxes that fill the trunks, back seats, and passenger seats. There's more than four hundred dead and injured birds in total, plus a few bats.

It's been a bad night for the birds, says Annette, but it's far from the worst. What's more, the birds they have recovered are merely the tip of the iceberg. Not only will the volunteers have missed some, but plenty never reach the ground and lie dead or dying on the balconies, awnings, overhangs, and tiered rooftops of buildings. They are the unlucky ones. No one will be coming to save them.

The annual death tolls are huge. Across the United States, an estimated six hundred million birds are killed by flying into buildings every year. Most of the deaths are due to collisions with
residential and low-rise properties. High-rises account for just half a million, but there are far fewer skyscrapers out there and they have the highest kill rate of any building type.

For those hoping to help the birds, the focus is very much on how buildings can change. Many cities, Chicago included, have Lights Out programs that have helped make urban areas less likely to draw in migrating birds.

But some have gone further, and Toronto is the city that's been setting the pace. Since 2010 the Canadian city has required new buildings, aside from low-rise residential properties, to comply with its “bird-safe” design policies. These rules include using glass that mutes reflections or is patterned in a way that makes them more noticeable to birds and not putting rooftop gardens next to windows. In addition, only heritage buildings can have exterior lighting that points skyward.

Other cities have followed suit with rules of their own. Among them is Oakland, California, which requires developers to install timers or motion sensors that switch off interior lights so they can't be left on by accident and to avoid using mirrors in landscape design. San Francisco and the state of Minnesota have also introduced similar policies.

Architects are also picking up the baton. In Chicago, Jeanne Gang designed the eighty-two-story Aqua Tower on North Columbus Drive to be bird-safe by incorporating fritted glass with a gray dot pattern and undulating exterior terraces that make the skyscraper look like a cliff edge. “Each building has a pathology to it,” says Annette. “It's all the elements combined. How it's designed, how the right angles are, and whether it's near something green,” like a rooftop garden.

There are, however, difficulties in figuring out what works. Some have suggested that avoiding particular colors of light, such as red, can help but Graham believes the evidence isn't there yet. “Color doesn't seem to make a difference,” he says. “There are people trying different color lights to see whether it makes a difference
and there was a claim that it did, but I don't think it is very convincing at the moment.”

One example is how people got hung up on the potential of applying ultraviolet patterns to glass because birds can see ultraviolet while we can't. “UV sensitivity in birds is very oversold,” says Graham. “Their actual sensitivity to UV is really quite low. There's nothing special about it—it's probably more to observe plumages at close range than anything more. People have been playing around with UV markings on windows that are invisible to us but visible to birds, but that doesn't seem to have any effect. It's probably just light rather than anything specific.”

Of course it is much easier to address the factors that attract birds when designing new buildings but, says Annette, existing buildings can be improved. “You can't fix an entire building, but our records show localized places on buildings where the strikes are occurring, and there are often simple or temporary measures you can do that significantly reduce the number of bird collisions,” she says.

One such measure is moving vegetation away from windows. “Putting a green space that's attractive to birds right next to a glass window is like putting candy next to a swimming pool with no fence on,” she says. “The kids come for the candy, fall in the swimming pool, and drown. You can't fix a whole building with multiple stories, but if there's anything you can fix it's having a green area right next to the window or plants inside next to the window. So that's what we try to persuade buildings to do. People aren't going to build buildings without windows in them.”

And, she thinks, the building owners are generally up for trying to make cities safer for birds. “I don't think any of the buildings want to be hurting birds, and I think the Chicago skyline is spectacular on a beautiful day. It's just unfortunate that it's so deadly.”

Matt Bertone looks ready for a safari. He is wearing a khaki photographer's vest over his navy blue with white stripes polo shirt. The vest pockets bulge with equipment that includes a bunch of clear plastic vials, a handheld torch, and a pair of metal tweezers. Wrapped around his legs are black and yellow kneepads, and a headlamp is affixed to his shaven head. The final touch is the aspirator, the device that entomologists like Matt use to suck up insects. Its clear tubes are slung around his neck, the sucking end in easy reach of his mouth.

It is the outfit of a man who is about to search the Amazon for a new species of caterpillar, but there's no rainforest here. Instead, Matt is standing next to the breakfast bar in the open-plan kitchen of a suburban house in Raleigh, North Carolina.

It's an ordinary home. A silver kettle and wooden chopping board sit on the granite worktop. Pictures of the homeowners' kids are on display in the cupboard windows and a frying pan hangs from the range hood. At the far end of the room are sofas arranged around a flat-screen TV. The only plants here are in vases.

It is hard to imagine anywhere less like a rainforest, but looks can be deceptive. This might be a home, but it is also an ecological unknown. Scientists know more about life in the Amazon and deepest parts of the ocean than they do about the cave-like habitats that are our houses.

The ecology of the home is a mystery, a blank page yet to be written, and Matt, who works at North Carolina State University, and his colleague Michelle Trautwein of the North Carolina Museum of Natural Sciences have made it their mission to fill in some of the blanks. “Shall we find some bugs?” asks Matt. We nod, and he and Michelle get to work.

Matt flicks on the bright white light of his headlamp and homes in on the gas cooktop. He leans over it and sucks something up with his aspirator. He empties the find into the palm of his hand. “This looks like a shed skin of something,” he says. He drops it into one of the vials, grabs his tweezers, and starts plucking more specks from the join between the work surface and tiled wall. I tell Matt that they look like nothing more than tiny pieces of fluff. “Actually, more often you pick up insects that you think are fluff,” he replies, turning his attention to the small kitchen window.

“The windowsills are the best,” he says, homing in on a crumpled insect. “Already, a huge crane fly.” The crane fly is dead but well preserved. Its delicate wings with their network of black veins are undamaged as are the fly's long spindly legs, which bring to mind the tripods from H. G. Wells'
The War of the Worlds.
Matt adds it to the alcohol-filled vial.

Next, he spots a tiny, lifeless spider in the corner of the windowsill. “A cellar spider. It's a common one that we find on the first floors of houses. I bet there's one in every corner. And this, this is a little ichneumon wasp,” he says, plucking up the insect next to the spider from the sill.

Ichneumon wasps are a very different type of wasp from the more familiar yellow-and-black picnic menaces. They are solitary parasites that plant eggs in the bodies of other arthropods so their
larvae can eat their host alive from the inside out. The wasp Matt has found is jet black and the segments of its hook-shaped abdomen make it look armor plated. “This looks like it's from the subfamily Pimplinae,” says Matt, whose expertise in insect identification makes him a rarity even among entomologists. “If it is, it might parasitize spiders. They could be in the home parasitizing things.”

One type of parasitic wasp has been found time and time again in the Raleigh houses that Matt and Michelle have been surveying for their Arthropods of Our Homes project. Matt doesn't know exactly what species it is yet. Identifying insects down to species level is challenging at the best of times, and parasitic wasps are one of the toughest groups to classify. There are thousands of species, many are small, and they often look alike.

But Matt has a hunch. He thinks the most common parasitic wasp in Raleigh houses specializes in laying eggs in the eggs of cockroaches. “These wasps are really little—they have to be because they are egg parasites,” he says. Too small to be our Pimplinae wasp, then.

While Matt has been sorting through the arthropods near the kitchen work surfaces, Michelle has been checking the living room window looking out to the backyard. She shows me her haul. One large shiny bluebottle and a smattering of tiny flies. “This big one's a Calliphoridae, possibly
Calliphora vomitoria
—a common trash-visiting and food-visiting fly, but, at the same time, there is this bunch of tiny gnats,” she says. “We've got one, two, three, four … five, six. At least six different types of fly.”

Flies, including mosquitoes, are the most common type of arthropod we share our homes with. They accounted for just over a quarter of all the species in the Raleigh houses. Beetles come next at 17 percent, followed by ants, bees and wasps at 15 percent. Spiders form the last big group, making up 14 percent of the finds. “We find more fly species associated with houses than any other group, but there's a lot of fly diversity,” says Michelle.

To say there are “a lot” of fly species feels like an understatement. One in every ten known animals is a fly and it is believed
that a great, great many more than the 150,000 known fly species are out there waiting to be discovered. “The two flies we find most often are the two people know about—the house fly and then the little fruit flies you see buzzing around your fruit. Both originated in Africa, just like we did. We dispersed around the world and they have followed us. There are house flies in old Egyptian mummy sarcophagi.”