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Street coyotes more faithful than people, study suggests

Sept. 25, 2012
Courtesy of Ohio State University
and World Science staff

Coy­otes liv­ing in ur­ban areas nev­er stray from their mates—they stay to­geth­er till death do them part, ac­cord­ing to a new stu­dy.

Sci­en­tists say the find­ing sheds light on why the North Amer­i­can cous­in of the dog and wolf, which is orig­i­nally na­tive to deserts and plains, is thriv­ing to­day in metro­pol­is­es.

Stan Gehrt, a wild­life ecol­o­gist at Ohio State Uni­ver­si­ty, in­spects a coy­ote cap­tured in the great­er Chi­ca­go ar­ea as part of a long-running study on this in­creas­ing­ly com­mon ur­ban res­i­dent. (Pho­to cour­te­sy of Stan Gehrt)


Re­search­ers with Ohio State Uni­vers­ity who ge­net­ic­ally sam­pled 236 coy­otes in the Chi­ca­go ar­ea over a six-year pe­ri­od found no ev­i­dence of polygamy—of the an­i­mals hav­ing more than one mate—nor of one mate ev­er leav­ing an­oth­er while the oth­er was still alive. 

That was true, the sci­ent­ists said, even though the coy­otes live in dense­ly packed pop­ula­t­ions with plen­t­iful of food, con­di­tions that of­ten lead some oth­er mem­bers of the dog family to stray from their nor­mal mo­nog­a­my. 

“I was sur­prised we did­n’t find any cheat­ing,” said study co-au­thor Stan Gehrt, a wild­life ecol­o­gist at Ohio State. “Even with all the op­por­tun­i­ties for the coy­otes to phi­lan­der, they really don’t.

“In con­trast to stud­ies of oth­er pre­sumably mo­nog­a­mous spe­cies that were lat­er found to be cheat­ing, such as arc­tic fox­es and moun­tain blue­birds, we found in­cred­i­ble loy­al­ty to part­ners in the study popula­t­ion,” he added.

The re­search ap­pears in a re­cent is­sue of The Jour­nal of Mam­mal­o­gy.

Coy­otes’ loy­al­ty may be a key to their suc­cess in ur­ban ar­eas, Gehrt said. Not only is a fe­male coy­ote nat­u­rally ca­pa­ble of pro­duc­ing large lit­ters of young dur­ing times of plen­ty, such as when liv­ing in food-rich ­ci­ties, she has a faith­ful part­ner to help raise them all. “If the fe­male were to try to raise those large lit­ters by her­self, she would­n’t be able to do it,” said Gehrt. “But the male spends just as much time help­ing to raise those pups as the fe­male does.”

Un­like the males of po­lyg­a­mous spe­cies, a male coy­ote “knows that ev­ery one of those pups is his off­spring” and has a clear ge­net­ic stake in help­ing them sur­vive, Gehrt said.

The re­search was done in Cook, Kane, Du­Page and Mc­Hen­ry coun­ties in great­er Chi­ca­go—home to about 9 mil­lion peo­ple and an es­ti­mat­ed 1,000 to 2,000 coy­otes. Gehrt has pre­vi­ously said he “could­n’t find an ar­ea in Chi­ca­go where there weren’t coy­otes.”

“Y­ou’ve got lots of coy­otes in this land­scape,” said sen­ior au­thor Ce­cil­ia Hen­nessy, who con­ducted the study as a mas­ter’s de­gree ad­vis­ee of Gehrt. “Y­ou’ve got ter­ri­to­ries that abut each oth­er. And coy­otes can make long-dis­tance for­ays. So you’d think, based on pre­vi­ous in­ves­ti­ga­t­ions of dog be­hav­ior, that cheat­ing would be like­ly.

“But to find noth­ing, ab­so­lutely noth­ing, no ev­i­dence whatsoev­er of an­ything that was­n’t mo­nog­a­my, I was very sur­prised by that,” she said.

The find­ing came through a wid­er study of Chi­ca­go-ar­ea coy­otes that Gehrt has led since 2000. As the larg­est study ev­er on ur­ban coy­otes, it’s a long-term ef­fort to un­der­stand the an­i­mals’ popula­t­ion ecol­o­gy, how they adapt to ur­ban life and how to re­duce their con­flicts with peo­ple.

The sci­en­tists used harm­less traps to catch adult coy­otes for the stu­dy, where­as pups were dug from their dens and held by hand. Small blood and tis­sue sam­ples were tak­en. The adults, which were an­es­the­tized, al­so were fit­ted with ra­di­o col­lars to track them. Af­ter­ward, all the coy­otes were re­leased where they were caught. Hen­nessy used ge­net­ic tech­niques in the lab to test the an­i­mals’ DNA and de­ter­mine their family trees.

A male coy­ote, for his part, prac­tices dil­i­gent mate guard­ing—keep­ing oth­er males away from his mate. Dur­ing es­trus, the time when the fe­male can be­come preg­nant, the pair spends all their time to­geth­er—running, find­ing food, mark­ing their ter­ri­to­ry, the sci­en­tists said.

“We’ve been able to fol­low some of these al­pha pairs through time, and we’ve had some of them stay to­geth­er for up to 10 years,” Gehrt said. 

“They sep­a­rate only up­on the death of one of the in­di­vid­u­als, so they truly ad­here to that phi­los­o­phy, ‘Till death do us part,’” Hen­nessy said.


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Coyotes living in cities never stray from their mates—they stay together till death do them part, according to a new study. Scientists say the finding sheds light on why the North American cousin of the dog and wolf, which is originally native to deserts and plains, is thriving today in urban areas. Researchers with Ohio State University who genetically sampled 236 coyotes in the Chicago area over a six-year period found no evidence of polygamy—of the animals having more than one mate—nor of one mate ever leaving another while the other was still alive. That was even though the coyotes exist in high population densities and have plenty of food, conditions that often lead some other members of the dog family to stray from their normal monogamy. “I was surprised we didn’t find any cheating,” said study co-author Stan Gehrt, a wildlife ecologist at Ohio State. “Even with all the opportunities for the coyotes to philander, they really don’t. “In contrast to studies of other presumably monogamous species that were later found to be cheating, such as arctic foxes and mountain bluebirds, we found incredible loyalty to partners in the study population,” he added. The research appears in a recent issue of The Journal of Mammalogy. Coyotes’ loyalty may be a key to their success in urban areas, Gehrt said. Not only is a female coyote naturally capable of producing large litters of young during times of plenty, such as when living in food-rich cities, she has a faithful partner to help raise them all. “If the female were to try to raise those large litters by herself, she wouldn’t be able to do it,” said Gehrt. “But the male spends just as much time helping to raise those pups as the female does.” Unlike the males of polygamous species, a male coyote “knows that every one of those pups is his offspring” and has a clear genetic stake in helping them survive, Gehrt said. The research was done in Cook, Kane, DuPage and McHenry counties in greater Chicago—home to about 9 million people and an estimated 1,000 to 2,000 coyotes. Gehrt has previously said he “couldn’t find an area in Chicago where there weren’t coyotes.” “You’ve got lots of coyotes in this landscape,” said senior author Cecilia Hennessy, who conducted the study as a master’s degree advisee of Gehrt. “You’ve got territories that abut each other. And coyotes can make long-distance forays. So you’d think, based on previous investigations of dog behavior, that cheating would be likely. “But to find nothing, absolutely nothing, no evidence whatsoever of anything that wasn’t monogamy, I was very surprised by that,” she said. The finding came through a wider study of Chicago-area coyotes that Gehrt has led since 2000. As the largest study ever on urban coyotes, it’s a long-term effort to understand the animals’ population ecology, how they adapt to urban life and how to reduce their conflicts with people. The scientists used harmless traps to catch adult coyotes for the study, whereas pups were dug from their dens and held by hand. Small blood and tissue samples were taken. The adults, which were anesthetized, also were fitted with radio collars to track them. Afterward, all the coyotes were released where they were caught. Hennessy used genetic techniques in the lab to test the animals’ DNA and determine their family trees. A male coyote, for his part, practices diligent mate guarding—keeping other males away from the female. During estrus, the time when the female can become pregnant, the pair spends all their time together—running, finding food, marking their territory, the scientists said. “We’ve been able to follow some of these alpha pairs through time, and we’ve had some of them stay together for up to 10 years,” Gehrt said. “They separate only upon the death of one of the individuals, so they truly adhere to that philosophy, ‘Till death do us part,’ “ Hennessy said.