May 01, 2012
Gray Wolves will sometimes kill Coyotes
that seek to scavenge their kill
click link toview video of this occurring in Yellowstone Park
https://www.youtube.com/watch?v=YcFtdnewTCU
Gray Wolves will sometimes kill Coyotes
that seek to scavenge their kill
click link toview video of this occurring in Yellowstone Park
https://www.youtube.com/watch?v=YcFtdnewTCU
Can wolves and coyotes coexist?
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As wolves disappeared in the
past, coyotes quickly moved in to occupy the vacated range. Now, the reverse
seems to be taking place; wolves are moving into reclaim range coyotes have
occupied for the past 100 years or more.
Some biologists support the view that wolves will replace coyotes in certain areas. Others suggest the "clever coyote" will learn to coexist with wolves. There is scientific evidence to support both views.
The Isle Royale Story
Historically, wolves may have played an important role in replacing coyotes on Isle Royale, located at the west end of Lake Superior. In less than 60 short years, the coyote arrived on Isle Royale, prospered for a time, declined, then disappeared altogether.
Some biologists support the view that wolves will replace coyotes in certain areas. Others suggest the "clever coyote" will learn to coexist with wolves. There is scientific evidence to support both views.
The Isle Royale Story
Historically, wolves may have played an important role in replacing coyotes on Isle Royale, located at the west end of Lake Superior. In less than 60 short years, the coyote arrived on Isle Royale, prospered for a time, declined, then disappeared altogether.
According to the late Laurits Krefting, a long-time wildlife research biologist
with the U.S. Bureau of Sport Fisheries and Wildlife, coyotes probably reached
Isle Royale by traveling over the ice from the Sibley Peninsula region of
Ontario, a distance of 15 miles, about 1906. (This is about the same time coyotes
were first observed in Michigan's UP.) Despite the less than favorable habitat
for them, coyotes flourished on the island, reaching peak numbers of about 150
animals, in 1948.
Krefting noticed that coyote numbers began to decline, starting in 1949, about the time Great Lakes Wolves(admix of Gray and Eastern Wolf) reached the island. The decrease in coyote numbers also came with a crash decline in the beaver population, a die-off of moose, a low snowshoe hare population and sustained human Trapper take. Coyotes disappeared from Isle Royale in 1957 or 1958.
"Even at its best," says Krefting, "the habitat on Isle Royale was marginal for coyotes. When strict fire protection was put into effect, the changes in plant succession gradually produced an even less favorable habitat. A reduced food supply and direct killing by wolves are the factors that probably contributed most to the coyote's disappearance. A combination of these and other factors plus the fact that it was an island situation probably was necessary to cause coyote extinction."
Coyote scavenging Wolf kill,,,,,,,,,,,,lean pickings
Hence, this may have been a rather unique situation. Certainly, the ecological nature of the island (i.e., dense conifers and lack of openings) is not what one would picture as coyote country. And, given its insular condition, the island undoubtedly lacks the diversity in flora and fauna characteristic of the adjacent mainland. This means there are few alternate prey for coyotes.
MANITOBA, CANADA
In Manitoba, Canada, researcher Ludwig Carbyn observed that Gray wolves frequently
killed coyotes but did not eat them(same in Yellowstone after Wolf re-introduction in 1995). He found no evidence that coyotes avoided
wolves during most of the year, but definitely did so from mid- to late-winter.
Carbyn theorized that differences in snow conditions, and learning on the coyote's part, may be involved in the coyotes changing response to wolves as the winter progressed. When snow is deep and soft, coyotes are hindered more than wolves. However, since coyotes often trailed wolves through deep soft snow, Carbyn rationalized although coyotes may avoid wolves after a "refractory period," they may actually trail them at a safe distance in search of food.
Wolves chasing down and killing a Coyote that sought
to scavenge their kill
Since wolves are territorial and may even kill their own kind when boundaries are trespassed, buffer zones exist between wolf territories where few wolves travel. Coyotes sometimes find these buffer zones safe havens. In Carbyn's study, coyotes were not always safe from wolves while in the buffer zone when wolf density was high. However, overall coyote survival appeared to be greater there during years of only moderate wolf density.
Carbyn theorized that differences in snow conditions, and learning on the coyote's part, may be involved in the coyotes changing response to wolves as the winter progressed. When snow is deep and soft, coyotes are hindered more than wolves. However, since coyotes often trailed wolves through deep soft snow, Carbyn rationalized although coyotes may avoid wolves after a "refractory period," they may actually trail them at a safe distance in search of food.
Wolves chasing down and killing a Coyote that sought
to scavenge their kill
Since wolves are territorial and may even kill their own kind when boundaries are trespassed, buffer zones exist between wolf territories where few wolves travel. Coyotes sometimes find these buffer zones safe havens. In Carbyn's study, coyotes were not always safe from wolves while in the buffer zone when wolf density was high. However, overall coyote survival appeared to be greater there during years of only moderate wolf density.
In another Manitoba study, Paul Paquet found coyotes scavenging
wolf-killed deer within 24 hours after abandonment by wolves. Although wolves
occasionally killed coyotes, Paquet saw no evidence of wolves actively
searching for coyotes. Neither was there any evidence that coyotes adjusted
their movements to avoid wolves.
In the area where Paquet conducted his study, elk served as the major winter food for both wolves and coyotes. Wolves killed elk while coyotes scavenged the remains. In this regard, coyotes weren't dumb. As Paquet notes, "Because predation on [large prey] involves considerable risk of injury and is likely energetically expensive owing to a low rate of success, there is no apparent advantage in killing prey if good quality food can be scavenged."
This wolf-coyote relationship is interesting because the primary source of food was large prey, leaving enough food for both wolves and coyotes. However, it may be a different story when both predators must exist primarily upon smaller prey such as deer.
Coyote scavenging the few "leftovers" of a Wolf kill
"If deer are the preferred prey," notes Paquet, "then coyotes lose the opportunity to scavenge wolf kills because wolves preying on deer leave few remains."
Findings from studies conducted by Minnesota researcher Glen DelGuidice add a new twist to this story. Apparently, during especially severe winters (i.e., deep snow for four to eight weeks), wolves exhibit surplus killing of deer with no or low consumption of the carcass. Under such conditions wolves may kill many more deer than normal and benefit coyotes by leaving more for them to scavenge.
Recolonizing Wolves in Montana
One of the more recent investigations into coyote-wolf interactions was by Todd Atwood and Eric Gese. They conducted their work during the winters of 2003-04 and 2004-05, in northern Montana. This was shortly after wolves recolonized the region, presenting a unique opportunity to determine how naive coyotes adjust to the sudden presence of a competitively dominant canid that might threaten coyote survival in the region.
Atwood and Gese followed the activities of 29 radio-collared coyotes, belonging to 11 packs living within the 187 square mile home range of the Bear Trap wolf pack. Before pups were born, coyote pack size averaged 4 adults. Wolf pack size varied from 2 to 8 and averaged 5 individuals. In addition, the researchers followed nearly 1000 miles of coyote tracks and over 300 miles of wolf tracks in the snow.
A Coyote who sought to scavenge a Wolf kill, mauled by Wolf pack
Atwood and Gese located 92 wolf kills (presumably elk and deer), 77 (85 percent) of which were visited by coyotes. They witnessed 36 conflicts, involving 6 different coyote packs and the Bear Trap wolf pack, at wolf-kill sites. Although coyotes gained possession of the contested carcass on 17 occasions, all such carcasses were already nearly depleted. During the course of study, wolves killed one adult coyote and 2 pups, whereas 3 adult coyotes were killed by cougars; all such mortalities occurred within 200 meters of a wolf-killed deer or elk.
In most cases, wolves were able to drive coyotes away from deer or elk kill sites until they had their fill. Generally, coyotes gained access to wolf killed prey only when coyotes outnumbered wolves and only after wolves had already consumed most of their kill.
Interestingly, coyotes were able to spend more time at wolf-kill sites during the second winter of study, as compared to the first. As a result, formerly naive coyotes might have learned, through previous experience, to exploit carcasses in the latter stages of consumption when wolves were more inclined to back off.
A moment before the two Wolves take down a Coyote who sought
to scavenge the Wolves kill
Atwood and Gese concluded the following: "Coyotes do not perceive wolves as a threat requiring generalized spatial avoidance. Rather, the threat of aggressive interactions with wolves is spatially discrete and primarily contained to areas adjacent to carrion resources."
Although the researchers don't dwell on the point, these findings imply that coyotes in northern Montana are learning to cope with wolves, and may even benefit from the larger canid's presence.
Conclusions
The gray wolf is definitely coming back to re-claim historic range it lost to coyotes decades ago. What will happen to coyotes in the meantime is anyone's guess. Some predict the demise of coyotes, whereas others believe coyotes will adjust, and maybe even prosper, in the presence of a more dominant canid.
The outcome will vary from one area to the next, depending upon a host of environmental circumstances.
Ironically, at least across the whitetail's northern range, both predators will benefit from man's mismanagement of deer wintering habitat. Resultant poor quality winter habitat, when coupled with the presence of two capable deer predators, will undoubtedly lead to excessive deer mortality during and following severe winters -- and ultimately contribute to declining deer numbers.
Just remember, coyotes are survivors. They are the clever predator that humans couldn't eradicate with all their traps, poisons, and guns. I don't expect wolves to be any more successful. In fact, here in Michigan's UP, deer hunter sighting rates of coyotes have doubled, while that of wolves have tripled, in the past 10 years.
In the area where Paquet conducted his study, elk served as the major winter food for both wolves and coyotes. Wolves killed elk while coyotes scavenged the remains. In this regard, coyotes weren't dumb. As Paquet notes, "Because predation on [large prey] involves considerable risk of injury and is likely energetically expensive owing to a low rate of success, there is no apparent advantage in killing prey if good quality food can be scavenged."
This wolf-coyote relationship is interesting because the primary source of food was large prey, leaving enough food for both wolves and coyotes. However, it may be a different story when both predators must exist primarily upon smaller prey such as deer.
Coyote scavenging the few "leftovers" of a Wolf kill
"If deer are the preferred prey," notes Paquet, "then coyotes lose the opportunity to scavenge wolf kills because wolves preying on deer leave few remains."
Findings from studies conducted by Minnesota researcher Glen DelGuidice add a new twist to this story. Apparently, during especially severe winters (i.e., deep snow for four to eight weeks), wolves exhibit surplus killing of deer with no or low consumption of the carcass. Under such conditions wolves may kill many more deer than normal and benefit coyotes by leaving more for them to scavenge.
Recolonizing Wolves in Montana
One of the more recent investigations into coyote-wolf interactions was by Todd Atwood and Eric Gese. They conducted their work during the winters of 2003-04 and 2004-05, in northern Montana. This was shortly after wolves recolonized the region, presenting a unique opportunity to determine how naive coyotes adjust to the sudden presence of a competitively dominant canid that might threaten coyote survival in the region.
Atwood and Gese followed the activities of 29 radio-collared coyotes, belonging to 11 packs living within the 187 square mile home range of the Bear Trap wolf pack. Before pups were born, coyote pack size averaged 4 adults. Wolf pack size varied from 2 to 8 and averaged 5 individuals. In addition, the researchers followed nearly 1000 miles of coyote tracks and over 300 miles of wolf tracks in the snow.
A Coyote who sought to scavenge a Wolf kill, mauled by Wolf pack
Atwood and Gese located 92 wolf kills (presumably elk and deer), 77 (85 percent) of which were visited by coyotes. They witnessed 36 conflicts, involving 6 different coyote packs and the Bear Trap wolf pack, at wolf-kill sites. Although coyotes gained possession of the contested carcass on 17 occasions, all such carcasses were already nearly depleted. During the course of study, wolves killed one adult coyote and 2 pups, whereas 3 adult coyotes were killed by cougars; all such mortalities occurred within 200 meters of a wolf-killed deer or elk.
In most cases, wolves were able to drive coyotes away from deer or elk kill sites until they had their fill. Generally, coyotes gained access to wolf killed prey only when coyotes outnumbered wolves and only after wolves had already consumed most of their kill.
Interestingly, coyotes were able to spend more time at wolf-kill sites during the second winter of study, as compared to the first. As a result, formerly naive coyotes might have learned, through previous experience, to exploit carcasses in the latter stages of consumption when wolves were more inclined to back off.
A moment before the two Wolves take down a Coyote who sought
to scavenge the Wolves kill
Atwood and Gese concluded the following: "Coyotes do not perceive wolves as a threat requiring generalized spatial avoidance. Rather, the threat of aggressive interactions with wolves is spatially discrete and primarily contained to areas adjacent to carrion resources."
Although the researchers don't dwell on the point, these findings imply that coyotes in northern Montana are learning to cope with wolves, and may even benefit from the larger canid's presence.
Conclusions
The gray wolf is definitely coming back to re-claim historic range it lost to coyotes decades ago. What will happen to coyotes in the meantime is anyone's guess. Some predict the demise of coyotes, whereas others believe coyotes will adjust, and maybe even prosper, in the presence of a more dominant canid.
The outcome will vary from one area to the next, depending upon a host of environmental circumstances.
Ironically, at least across the whitetail's northern range, both predators will benefit from man's mismanagement of deer wintering habitat. Resultant poor quality winter habitat, when coupled with the presence of two capable deer predators, will undoubtedly lead to excessive deer mortality during and following severe winters -- and ultimately contribute to declining deer numbers.
Just remember, coyotes are survivors. They are the clever predator that humans couldn't eradicate with all their traps, poisons, and guns. I don't expect wolves to be any more successful. In fact, here in Michigan's UP, deer hunter sighting rates of coyotes have doubled, while that of wolves have tripled, in the past 10 years.
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