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Friday, February 1, 2013

Urban coyotes could be setting the stage for larger carnivores -- wolves, bears and mountain lions -- to move into cities

Oct. 5, 2012 — About five miles from Chicago O'Hare International Airport, scientists have located the smallest known coyote territory ever observed. For at least six years, a coyote community has maintained its existence within about a third of a square mile.

"That's an indication that they don't have to go far to find food and water. They're finding everything they need right there, in the suburbs of Chicago," said Stan Gehrt, an associate professor of environment and natural resources at Ohio State University who has led the tracking of coyotes around Chicago for 12 years. "It amazes me."

Coyotes are the largest of the mammalian carnivores to have made their way to, and thrived in, urban settings, Gehrt said.

"The coyote is the test case for other animals. Raccoons, skunks, foxes -- they've already been able to penetrate the urban landscape pretty well. The coyote is the most recent and largest. The jury's out with what's going to happen with the bigger ones," he said.

The bigger ones include wolves, mountain lions and bears. Mountain lions have been seen on the fringes of cities already, and one was shot near the Wrigleyville neighborhood of Chicago.

"They are going to be an even bigger challenge," Gehrt said.

Since the tracking of urban coyotes began in 2000, Gehrt and his team have captured and placed radio collars on about 680 coyotes, with 50 or 60 being tracked at any one time. He estimates that about 2,000 coyotes live in the Chicago metro area, along with 9 million people in some 250 separate municipalities.

At times, this co-existence can cause uneasiness among humans. But by Gehrt's estimation, all species of urban dwellers are probably going to have to get used to it.

"It used to be rural areas where we would have this challenge of coexistence versus conflict with carnivores. In the future, and I would say currently, it's cities where we're going to have this intersection between people and carnivores," he said. "We used to think only little carnivores could live in cities, and even then we thought they couldn't really achieve large numbers. But we're finding that these animals are much more flexible than we gave them credit for and they're adjusting to our cities.

"That's going to put the burden back on us: Are we going to be able to adjust to them living with us or are we not going to be able to coexist?"

Gehrt described the research in a talk October 5 at EcoSummit 2012, an international conference held in Columbus.

The tricky part of any government-sponsored eradication program is the question of cost versus benefit. When the study began in 2000, several communities around Chicago trapped and killed coyotes found within their boundaries. Gehrt estimates that only 10 percent of communities have such programs in place now.

"I think those programs will go away, too. It costs money, and it upsets some residents who want coyotes living there. So there is conflict, cost and lack of effectiveness. We have great data in areas where removal was done. You pull them out, and literally within just a few weeks, new coyotes moved in and set up a new pack and began reproducing right away," he said.

Gehrt noted that the encroachment goes both ways. Humans have not been a predominantly urban species for all that long worldwide, though about 80 percent of U.S. residents live in cities. One reason humans flocked to cities was to get away from the risks associated with living near wild carnivores.

"The funny thing is that now we have more people on earth and bigger cities than ever, we also now have carnivores moving into cities. It's a two-way street: We're expanding cities into their territories and they're also coming in," said Gehrt, who also holds appointments with the Ohio Agricultural Research and Development Center and Ohio State University Extension.

In comparing his findings about coyote survival in cities to research by another group on those living in rural areas, Gehrt has found that the urban coyote pup survival rate is five times higher than the rate for rural pups. In both environments, humans are the coyotes' primary predator.

"We are the only thing slowing their population down, either with our cars, which is the No. 1 cause of death for coyotes, or when we remove them through hunting or control programs," Gehrt said. "None of the diseases they're exposed to really impact them at all."

Coyotes are exposed to disease because they dine on rodents, rabbits and geese, providing a benefit by reducing human exposure to diseases carried by those species and removing animals otherwise considered a nuisance. They will also eat bugs and deer fawn, another potential benefit because human encounters with deer can be deadly, and will gorge on fruit if given the opportunity. They also eat the occasional cat or small dog.

Opportunity for food appears to abound in urban areas, which is why coyote communities can thrive in such small, contained spaces. Once they settle, resident coyotes don't move much. Transient animals, typically youngsters that have recently left their parents' pack, will try to find a vacancy in an existing territory or find a new area to start their own pack.

"They're so adaptable and so opportunistic," Gehrt said. "In adjusting to urban life, they may change dietary items and habitat use, and become nocturnal, whereas in the country they're active day and night. But with other things, they don't change at all. Here, they're able to maintain their social structure, territorialism, packs and mating system, even in the face of all these challenges of trying to live among 9 million people."

Gehrt recently published a paper describing how coyotes in Chicago have remained monogamous in the midst of adjusting to their new, urban way of life.

He is expanding his research to a few other sites, including Cleveland, Ohio, and in Nova Scotia, where coyotes show more aggressiveness toward humans.

However, under typical circumstances, Gehrt said coyotes are not prone to attack humans. For those people who see a coyote and do feel threatened, waving one's arms and yelling, or even throwing a rock in its direction, will very likely scare the animal away.

"You're doing them a favor. They show a healthy respect and fear of people and that's the way it should be."

Gehrt's study is funded by Cook County (Ill.) Animal & Rabies Control.

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The above story is reprinted from materials provided by Ohio State University. The original article was written by Emily Caldwell.

Note: Materials may be edited for content and length. For further information, please contact the source cited above.

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Why wolves are forever wild, but dogs can be tamed

Jan. 17, 2013 — Dogs and wolves are genetically so similar, it's been difficult for biologists to understand why wolves remain fiercely wild, while dogs can gladly become "man's best friend." Now, doctoral research by evolutionary biologist Kathryn Lord at the University of Massachusetts Amherst suggests the different behaviors are related to the animals' earliest sensory experiences and the critical period of socialization. Details appear in the current issue of Ethology.

Until now, little was known about sensory development in wolf pups, and assumptions were usually extrapolated from what is known for dogs, Lord explains. This would be reasonable, except scientists already know there are significant differences in early development between wolf and dog pups, chief among them timing of the ability to walk, she adds.

To address this knowledge gap, she studied responses of seven wolf pups and 43 dogs to both familiar and new smells, sounds and visual stimuli, tested them weekly, and found they did develop their senses at the same time. But her study also revealed new information about how the two subspecies of Canis lupus experience their environment during a four-week developmental window called the critical period of socialization, and the new facts may significantly change understanding of wolf and dog development.

When the socialization window is open, wolf and dog pups begin walking and exploring without fear and will retain familiarity throughout their lives with those things they contact. Domestic dogs can be introduced to humans, horses and even cats at this stage and be comfortable with them forever. But as the period progresses, fear increases and after the window closes, new sights, sounds and smells will elicit a fear response.

Through observations, Lord confirmed that both wolf pups and dogs develop the sense of smell at age two weeks, hearing at four weeks and vision by age six weeks on average. However, these two subspecies enter the critical period of socialization at different ages. Dogs begin the period at four weeks, while wolves begin at two weeks. Therefore, how each subspecies experiences the world during that all-important month is extremely different, and likely leads to different developmental paths, she says.

Lord reports for the first time that wolf pups are still blind and deaf when they begin to walk and explore their environment at age two weeks. "No one knew this about wolves, that when they begin exploring they're blind and deaf and rely primarily on smell at this stage, so this is very exciting," she notes.

She adds, "When wolf pups first start to hear, they are frightened of the new sounds initially, and when they first start to see they are also initially afraid of new visual stimuli. As each sense engages, wolf pups experience a new round of sensory shocks that dog puppies do not."

Meanwhile, dog pups only begin to explore and walk after all three senses, smell, hearing and sight, are functioning. Overall, "It's quite startling how different dogs and wolves are from each other at that early age, given how close they are genetically. A litter of dog puppies at two weeks are just basically little puddles, unable to get up or walk around. But wolf pups are exploring actively, walking strongly with good coordination and starting to be able to climb up little steps and hills."

These significant, development-related differences in dog and wolf pups' experiences put them on distinctly different trajectories in relation to the ability to form interspecies social attachments, notably with humans, Lord says. This new information has implications for managing wild and captive wolf populations, she says.

Her experiments analyzed the behavior of three groups of young animals: 11 wolves from three litters and 43 dogs total. Of the dogs, 33 border collies and German shepherds were raised by their mothers and a control group of 10 German shepherd pups were hand-raised, meaning a human was introduced soon after birth.

At the gene level, she adds, "the difference may not be in the gene itself, but in when the gene is turned on. The data help to explain why, if you want to socialize a dog with a human or a horse, all you need is 90 minutes to introduce them between the ages of four and eight weeks. After that, a dog will not be afraid of humans or whatever else you introduced. Of course, to build a real relationship takes more time. But with a wolf pup, achieving even close to the same fear reduction requires 24-hour contact starting before age three weeks, and even then you won't get the same attachment or lack of fear."

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The above story is reprinted from materials provided by University of Massachusetts at Amherst.

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Journal Reference:

Kathryn Lord. A Comparison of the Sensory Development of Wolves (Canis lupus lupus) and Dogs (Canis lupus familiaris). Ethology, 2013; 119 (2): 110 DOI: 10.1111/eth.12044

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Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.


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