The Weird Ways Animals Use Roads, Buildings and Power Lines to Their Advantage

Animals are often able to adapt to their human-influenced surroundings with remarkable ease.

(Inside Science) -- In 2012 and 2013, Bill Bateman, a zoologist based in Perth, Australia, began to notice something interesting about how animals were navigating the bush: When mining companies created small paths through the previously tangled environment to install seismic lines, animals started preferentially using those trails to move from one place to another.

“The more we looked, the more evidence there was that anthropogenic structures were often used to the advantage of these animals,” said Bateman, who works at Curtin University.

People usually think of any activity done by humans out in the wild as innately negative, but the more Bateman looked, the more he found animals adapting to take advantage of the human-built environment. From power lines to buildings and roads, wild animals do adapt to the world of humans -- and some of them even thrive on it.

Take squirrels in Manhattan, for example. Research by Bateman in 2014 shows how they create foraging spaces even in the densest urban environment, and how they use power lines and buildings to cross over roads. “Whether they are prey or predators, animals think of power lines and buildings as cliff faces and trees,” Bateman said.

A new study furthers that idea. In Thailand’s tropical forests, small thrushlike birds called White-rumped Shamas who nest near roads are more successful than those far from human activity – mostly because they avoid key predators by sticking to the roads (predators tend to stick to the deeper forests). Rongrong Angkaew, a research assistant at King Mongkut’s University of Technology Thonburi and her colleagues set 200 shoe box-sized nesting boxes around an environmental research station in northeast Thailand. Half were in the forest’s interior, and the other half were near a road.

They monitored the nests and attached radio trackers to fledglings for seven weeks, sometimes checking the nests multiple times each day to catch the baby birds when they emerged from the eggs. They found that the percentage of nests that had at least one successful egg (known as nest success) was 12 percent higher and post-fledging survival 24 percent higher at the edge versus the interior -- the opposite of the pattern commonly observed in temperate regions, where predators usually gravitate toward the edges of habitat. The study was published last week in the journal Condor.

The bird’s main predators are pig-tailed macaques and green cat snakes, explained Angkaew. “Macaques avoid this area and that’s why we see this pattern of increased survival,” she said.

Not all species benefit from the built environment. Although some predators could find more prey near roads, highways often act as death zones where slow-moving species get plowed over by cars. The effect can be exponential: In Australia, when reptiles are killed by cars, birds come to forage, and then they run the risk of being hit by cars also.

“Roads can start acting as an ecological trap,” said Bateman. “Roads can potentially have a footprint that goes much further out into the environment on each side, with depressed population of species on either side.”

And researchers are still trying to figure out why similar species have really different reactions to living near humans. For example, stone martens in Europe are often found thriving in towns in Belgium and Luxembourg. They live anywhere, including in roof spaces. On the other hand, pine martens are struggling to survive in an increasingly urbanized world. The trick of stone martens, said Bateman, is their adaptability: “Stone martens are more adaptable in eating all sorts of human rubbish left lying around, they’re more active later at night when they’re less likely to be disturbed by people,” even though to the common observer, the two species look very similar. One is doing well, and one isn’t.

Similarly, American badgers and European badgers have fared differently in towns and cities. While people visiting parks in the middle of London often see European badgers, the American badger is more a specialized rodent eater and doesn’t do well in the midst of human disturbance.

Human interventions can also have a consciously positive influence on biodiversity, Bateman pointed out. “It’s very easy to rapidly improve the situation for native bees and honeybees just by planting the right kinds of plants,” he said. Studies show that pollinator diversity can be as high in urban areas as natural areas when people are coaxed to plant bee-friendly plants.

It may be an adjustment for people to see cities as potential biodiversity hotspots, especially as cities grow in what were once wild areas.

“If there is one environment that is continuing to spread and grow, it is the urban environment,” said Bateman. “So, any understanding of how that negatively and positively affects animals is useful to know.”

None of this is news to me, I’ve been watching animals adapt to our buildings and so forth for years. Any time a lane is cleared for power lines, deer and other animals use it as a highway. Put in a fence and keep it cleared of weeds for a few feet, it will be used especially at night like a highway by deer, raccoons, foxes, rabbits, opossums, skunks, pretty much everything on 4 feet.

I spotted tracks of a huge cat, panther I think, 3 feet from my boat parked on the bank of the lake 100 yards away. We heard it scream many times, I saw the reflection of its eyes in my flashlight one night, never did see it in daylight.

Pigs have wiped out every garden in the neighborhood several times. Birds and squirrels use our gardens constantly and it’s almost impossible to stop it. I’ve seen squirrels run off with full size ears of corn and green tomatoes bigger than baseballs. They wipe out my peaches, pears and pecans every year. They pick them just before they are ripe enough for humans, drag them out into the woods and munch, and use tree limbs and power lines to get there.

An uncle worked in the print shop for a large Houston company. A Peregrine Falcon built a nest on the top of a building just outside an office. The company closed that office until the baby birds had left the nest, employees could still peek in but had to be quiet about it and try not to disturb the birds.

I have bird boxes around my yard, I have Bluebirds, Carolina Chickadees and Prothonotary Warblers nesting in them every year the past 5 years. They use fences, clothesline poles and wire, power lines, my carport, everything in sight for “roads” and perches and I make sure I leave out some short string, a few smallish branches and plenty grass cuttings for nesting materials. I also set out bird feeders, and get plenty pictures from those too.

Saw a documentary about squirrels a while back, they can outwit every squirrel proof feeder ever made. The show opened with a video of one climbing into a candy machine, coming back out and dragging a Baby Ruth bar down a city street, under cars, down the sidewalk...the thing went inside the candy machine...zip...gone...I don’t think he put a quarter in the slot either...

They set up an obstacle course with everything they could think of, squirrels were able to navigate it to the feeder in under 2 weeks. Put a feeder on a pole and smeared it with vaseline, the squirrel ran up and slid down over and over until it wiped off the grease and got into the food.

Someone developed an ingenious bird feeder with a plate on front and a counter weight on back. A bird does not weigh much, they can stand there and eat all they want. A squirrel is heavier and brings down the counterweighted plate, pulling a hood down over the food trough/slot. In a couple of weeks, they figured out one could stand on front, one on back and it would not close.

Another fellow set up a valve inside with a water hose aimed at his bird feeder. He could turn on the water and it would squirt the squirrel when it got into the feeder. That only lasted a week or so until the squirrel figured out he was about to be squirted when he saw the man inside move toward the valve. He never got a direct hit again.

Yet another set up a bird feeder on the side of a building mounted on a short metal rod, about 2 feet long. He could reach out the window and get the feeder to refill it. He put round plastic disks about the size of a quarter that would spin if a squirrel tried to walk on them. After quite a few tries, the squirrel figured out he could just run like hell to the feeder and it was all over.

So far the only thing I know of that does any good at all is a good amount of hot cayenne pepper in the bird feed. Squirrels hate it but birds ignore it. A friend had a Budgie that would sit on the side of my coffee cup and eat all the hot pepper seeds I would bring over. I found out by accident when she asked me for some seeds, so I brought over a pepper sliced open and dried so she could use the seeds. The bird didn’t hesitate a few seconds, flew over and lit on my hand, started munching on the seeds. Birds apparently are not affected by the heat. They get into my pepper plants all the time but they don’t get many so I don’t mind.

Animals are not stupid by any means. Deer eat at human supplied feeders all the time. Put some corn in a 2 liter soda bottle with a large opening, and they will destroy it in a couple of months trying to paw at it and get to the corn. I used that as a deer feeder to thwart the squirrels, they get more deer corn than deer do in regular feeders. I used half a bag of corn a year, everyone else I knew used 5 or 6 bags. I set up 3 bottle feeders, each tied to a small tree with parachute cord.

European Starlings were brought here many years ago. Along with a couple of others, like the European Sparrow, known as House Sparrow here. In the 1800’s some bozo decided all the birds in Shakespeare’s plays needed to be in New York City. They immediately pushed the native birds out of their territory, some states offered a bounty for all the sparrows you could kill, Starlings are a nuisance in many cities today, and they nest in large colonies. On one of our remodeling jobs before I left Louisiana, we found a Starling nest 6 feet long and about 4 feet wide in the attic.

OK I dug out my bird book...the guy’s name was Eugene Scheiffelin. He released 60 European Starlings into Central Park in 1890, the next year 40 more. Within a few weeks a pair was nesting under the eaves of the American Museum of Natural History. They were in Connecticut and New Jersey by 1904, and had crossed the Allegheny Mountains by 1916. Illinois in 1925, California by 1942. Alaska - 1952... In 1926 they were spotted in Beaumont (It’s a Texas bird book) they now form huge flocks in all of Texas in winter and breed in almost every part of the state. I see them here in East Texas all the time.

One interesting feature, the Starling has muscles that operate the bill different than most birds, it pulls open rather than closed, allowing it to pry open plant stems and thick turf to reveal live and dormant insects. This is part of the reason it is able to push other birds out of their natural territory. It can get at food they never can.

The story is almost the same for the House or European Sparrow. Introduced in 1850 or so, originally to fight an infestation of canker worms, it spread quickly and became a city nuisance all over the country. You see them in just about every parking lot you go to, I see them in Lowe’s and Home Depot stores here, and other stores, inside the gardening area too, almost every fast food place scavenging for discarded fries...they are in every grocery store parking lot here in town, on buildings, pretty much anywhere they find a shelf the size of a deck of cards to nest on they will, if it’s protected by some sort of overhang. These birds lost the urge to migrate long ago and set up a symbiotic relationship with humans, living in close proximity with us for hundreds of years.

Wood Ducks and some owls will also nest in artificial nesting boxes of the proper size, (and the same size too), I’ve put up small shelves around the house but none have been used yet. Smaller birds like Cardinals and Wrens will nest on such shelves, Wrens will nest in almost anything. I had a friend who found a nest in his work boots he had left on the porch one day...he just went and bought another pair, let them have the old ones. One evening, and wrens built a nest in his boots. Leave a coffee can sitting around, it’s a nest. Old shoes, my tool pouch for carpenter work, old pair of gloves, unused plant pots...virtually anything, wrens use it. They tried to build inside the fender of my Jeep but I kept driving off in it...

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