Feral Cities

by Tristan Donovan

  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.”

  SUBURBIA CRAWLING

  Bug Hunting in Raleigh Homes

  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.”

  A good proportion of the flies are phorid flies, also known as humpback flies. They are tiny. The biggest are no more than six millimeters long. The smallest is Euryplatea nanaknihali, the world’s smallest known fly. It measures a mere two-fifths of a millimeter long.

  Another famous phorid fly—well, famous among entomologists at least—is Megaselia scalaris. “It is probably the most prolific insect on Earth,” says Matt. “It seems to be everywhere around the world. It has even been found in an Antarctic research station. It feeds on everything: plants, fungus, paint, shoe polish. It’s parasitic too. They are insane. Basically, if they can eat it, they will eat it.”

  And, as you might imagine for an insect that eats shoe polish, it doesn’t care where it ends up. “Some were found alive in a snake that was preserved in formaldehyde in a jar,” says Matt. “I’ve found papers about them infecting the lungs of a python that had pneumonia. They were in there eating the bacteria.”

  Other common household invertebrates are equally unfussy about what they eat. Not least, the wingless silverfish that often live in bathrooms, where they eke out an existence feeding on everything from wallpaper and shaving foam to dandruff and shampoo. “It takes silverfish years to mature because they eat things like glue, paper, and leather,” says Matt. “They will eat really weird things that you don’t think are digestible.”

  Insects like silverfish and book lice have a long history of living with us, says Michelle. “Book lice are these tiny little things and we see them in almost every house. An insect leg or a hair can feed a book louse for months. They are dwarfed by mosquito legs. They are not parasitic—they live off your detritus. They were probably doing that with our ape ancestors, so it goes back millions of years.”

  While some household arthropods date back thousands of years, others are more recent colonizers. “Some of them are a reflection of how our lifestyles have changed,” she says. “So in living quarters of these houses in ancient Egypt there were dung beetles because human and animal waste was more closely associated with houses back then, whereas now we have got new species that are associated with indoor plumbing.”

  “I once found a dung beetle in my house,” Matt volunteers. “Not sure what that says about my house.”

  One more of these modern arrivals are drain flies, a group of flies whose fuzzy fur makes them look like mini-moths. As their name suggests, they find the drains of modern homes a good place to live. Their larvae live inside the pipes, munching on the moist slime that builds up until they metamorphose into flies that live for a couple of days at most.

  Or, at least, that is what they seem to be doing. Truth is, no one’s actually done the science. “It looks like they are feeding on microbes in drains, but nobody’s ever studied their biology or their evolution,” says Rob Dunn, the associate professor of biology at North Carolina State University who dreamt up the Arthropods of Our Homes project with Michelle. “There does not appear to be a single scientific paper on them, other than enough to know that they exist.”

  The roots of the Arthropods of Our Homes project lie in another of Rob’s studies, one that sought to find out what microbes live in homes. Like many of his studies, the microbes project was powered by citizen science with members of the public volunteering to have their homes swabbed for bacteria and other microscopic organisms.

  After gathering all the samples from people’s homes, Rob needed to give his army of volunteers something to do while he and his team pursued the time-consuming process of figuring out what bacteria they had found and analyzing the results. So he created a checklist of arthropods that people might find in their homes, e-mailed it to the volunteers, and asked them to report back on what they found in their game of creepy crawly bingo. One of the insects on the list was the camel cricket, a nocturnal brown cricket that gets its common name from its humped back. “I expected that people would find it as they sometimes turn up in basements, but that it wouldn’t be that common,” says Rob.

  But when the results came in, something was up. The numbers saying, ‘Yes, I have a camel cricket’ were much higher than expected. Not only that, they were clustered geographically, rather than being dotted randomly across the country. Rob was puzzled. Maybe, he thought, people are mistaking something else for a camel cricket.

  “There was this super-weird distribution. What we understo
od about these things is that they are a cave species and move into basements because they are like caves and that these crickets are all over North America. But when we mapped the results it was this weird smear on eastern North America. So we sent another e-mail saying send us a picture of it, because it’s possible people were looking at a squirrel and thinking they were camel crickets or whatever.”

  When the photos came back, it became clear that the volunteers weren’t mistaken. They had indeed found camel crickets in their basements, just not the one anybody expected. “Almost all of them turned out to be this invasive Japanese camel cricket. It looks similar but is a bit bigger and hoppier. It was known to be in the United States, but no one knew it had taken over basements across North America. I even had them in my own basement and didn’t realize they were the Japanese ones.”

  The most visible difference between the two species is color. The back of the US camel cricket has a mottled appearance while its Asian counterpart has dark and light brown stripes. Japanese camel crickets also lack the spikes that are on the hind legs of the American species. These may sound like superficial differences, but they are just the obvious signs of the huge evolutionary gulf that exists between the North American and Asian camel crickets. “There’s probably about twenty million years’ difference between them. It’s like thinking you have cats in the basement and you go and look and you realize it’s wild African dogs. They are that different,” says Rob.

  After finding the surprise camel cricket lurking in the nation’s basements, the idea for a deeper investigation into what is living in houses quickly took shape. Since then, Michelle, Matt, and the rest of the team have searched miles of baseboard and more than three hundred rooms in fifty Raleigh houses and collected more than ten thousand bugs.