If you've ever found garbage strewn across your yard after a raccoon raid or your picnic lunch has gone to the birds, you're well aware we share our suburbs and cities with a variety of four-legged and feathered "friends."

In fact, more animals are learning to live – and even thrive – in human environments as people increasingly encroach on their natural habitats. It certainly sounds positive that more wild critters are using their smarts, ingenuity and flexibility to adapt to our world instead of landing on the endangered list or fading into extinction.

But do the very traits that help them survive also put them into more conflict with their human neighbors?

The answer, according to a new study, is yes. It seems that animals most adept at coexisting with us (like crows and rats) are indeed the smartest. But that ability to continually improvise new life hacks for urban living also makes them the biggest mischief-makers — which paradoxically jeopardizes their survival as humans increasingly work to thwart their efforts, sometimes with deadly results.

Too smart for their own good

city crows City crows, like these in Tokyo, are able to memorize trash collection schedules — a smart survival strategy for them, but a messy headache for humans. (Photo: David Monniaux/Wikimedia Commons)

The study, published in the journal Animal Behaviour, examined a host of cognitive abilities that make some animal species particularly proficient at navigating the ever-evolving human landscape. These include neophilia (attraction to novelty), boldness, innovation, memory, learning, behavioral flexibility and ability to discriminate and categorize objects.

But these same attributes also make animals more likely to get into hot water with their human neighbors. For example, crows have razor-sharp memories that allow them to remember trash-collection schedules. Arriving on cue to dumpster-dive for dinner is a smart survival skill. But from a human perspective, crows' intelligence — along with their bold penchant for congregating in busy urban areas and leaving trash scattered in the streets — can be a downright nuisance.

Likewise, sea gulls in many coastal communities have taken to nabbing food straight from the hands of beachgoers. And at one temple in Bali, Indonesia, long-tailed macaques regularly steal cellphones, sunglasses and other valuables from tourists to trade (barter) for food.

You can watch marauding macaques in action below.

Unfortunately, impressive adaptive abilities can take a turn for the worse, as when wild animals end up killing livestock, colliding with vehicles, destroying crops and property, transmitting diseases and even killing human beings. Sadly, these transgressions often result in the use of lethal deterrents.

War of wits

Even when deterrents aren't deadly, problems still exist. The researchers found that as humans tried harder to stymie nuisance behaviors with humane deterrents, like loud noises, effigies (including scarecrows and plastic owls), bright lights and blockades, enterprising animals became better at circumventing them.

For instance, African bush elephants have learned to wield trees or use their tusks to disable electric fences designed to keep them out of crop fields, and raccoons and keas (a type of parrot found in New Zealand) regularly open "critter-proof" trash bins.

To see this kea cleverness, check out this video:

In other words, human-made barricades are regularly rendered impotent by fast-learning wildlife in what's becoming an ongoing game of one-upmanship.

"Animals that innovate novel ways to solve problems in their environment could drive a type of arms race with humans, where animals and humans work continuously to outsmart one another," says study co-author Lauren Stanton, a PhD student at the University of Wyoming's Animal Behavior and Cognition Lab, in a university statement.

Can't we all just coexist?

Interestingly, the study also revealed that some animals, like bobcats, red foxes, black bears and coyotes, are learning to lessen human contact or avoid humanity altogether by becoming more nocturnal. Other species have devised detours around dangerous freeways.

Even so, the researchers note that raccoons, coyotes and other wildlife are likely to grow bolder as they acclimate to urban sprawl, which will mean a greater need for more effective (and hopefully animal-friendly) strategies to deter unwanted behaviors.

"Given increasing human populations and expansion into animal habitat, there is a greater likelihood for human-wildlife conflict," adds co-author Sarah Benson-Amram. "Our work illustrates the need for research on a greater number of cognitive abilities in diverse species to understand how we can best mitigate these conflicts."

African elephant As their habitats dwindle, elephants are devising ever cannier ways to get food, including tearing down trees to disable crop-protecting electric fences. (Photo: Charles J Sharp/Wikimedia Commons)

One possibility is to use methods tailored to each species' perceptual predisposition. For example, effigies that change color, sounds and movements at irregular intervals might deter species that typically avoid novel or unfamiliar objects.

Or humans could turn destructive behaviors into positive ones by working cooperatively with nuisance species. In Sumatra, for example, specially trained elephants are being used to "herd" (drive away) their wild, crop-raiding cousins. And how about this win-win at a French theme park where rooks are being taught to use their trash-combing skills to collect and deposit litter in special garbage receptacles that pop out automatic food rewards?

As the study concludes: "Such innovative methods may not only redirect the attention of nuisance individuals away from conflict-prone activities, but also illustrate the cognitive capabilities of nonhuman animals, which in turn may promote a more harmonious relationship between humans and nuisance species."

The most mischievous animals are also the smartest
Brainy animals are getting better at surviving in our world – and causing mayhem.