Do Western Coyotes prey on adult Bison and/or Bison calves?.........."Bison appear to be a rare food source for Coyotes"........"In Yellowstone National Park,. Murie’s (1940) analysis of 5,086 Coyote scats showed a percentage occurrence of 0.20% Bison, and Murie found it unlikely that Coyotes would kill Bison calves, recording that anecdotal reports of the same “lacked proof”........."More recently, a 1995 study of Coyote Predation on Large Ungulates In Yellowstone revealed no killing of Bison by Coyotes(Gese and Grothe 1995)"............."Bison embody a formidable set of anti-predator adaptations, including well-developed maternal guarding behaviors (Carbyn and Trottier 1987, 1988)"..... "General herd behaviors of Bison cow-calf groups and size constraints (up the ante and greatly) regulate prey acquisition by the relatively small framed and light-weight Coyote"........."Certainly, predation attempts on ungulate neonates are a high risk activity for Coyotes"..........The 2009 recording of a Yellowstone Park Bison calf killed by an alpha male Coyote shows that predation on Bison calves may be possible under certain, albeit rare, conditions involving separation of a calf from its mother(Sheldon, Reed, Burnett, Li and Crabtree)"

https://www.google.com/url?rct=j&sa=t&url=https://www.usatoday.com/story/news/nation-now/2017/05/30/incredible-images-show-bison-protect-calf-coyote-yellowstone-national-park/355087001/&ct=ga&cd=CAEYBCoUMTI2MjA4NDM2NTQ5NjMyMTk0MzUyGmNmMTk3NTA4N2Y5NWNmOTY6Y29tOmVuOlVT&usg=AFQjCNG_fJmf9EuVy_tDi17Kge9QwXcbMA

Incredible images show bison protect calf from coyote at Yellowstone National Park

  USA TODAY Network; Mary Bowerman May 30, 2017

 Stunning photos show a bison defend her newborn calf from a coyote in Yellowstone National Park. 

The photos, taken by Ranger Joy Guffy, show the coyote attempt to chase the tiny calf and grab it, while the mother bison fights back.

CLICK ON THIS LINK TO WATCH THE MOTHER BISON PROTECT HER
CALF FROM THE COYOTE

http://makeagif.com/i/82vKr8

Yellowstone National Park shared the photos on Twitter Tuesday and called the coyote "determined." 

According to Yellowstone National Park, the bison had recently given birth. 

While there aren't numbers on the bison calfs killed by coyotes or wolves each year, it's not uncommon for the young to become targets, according Jonathan Shafer, a Yellowstone National Park spokesman.

"When it comes to smaller animals, they're definitely preferred prey," Shafer told USA TODAY in a phone interview. "It's easiest to catch something small." 

After giving birth, a cow bison successfully defended her newborn calf from a very determined coyote. (Courtesy Ranger Joy Guffy)

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Click on picture or 'COYOTE AND BISON CALF" phrase(link) below to view a Bison calf actually playing and chasing a Coyote......Note the Coyote staying well clear of the Mother Bison Coyote and Bison calf by Joe Holliday --------------------------------------------------------------------------------------------------- http://journals.sfu.ca/cfn/index.php/cfn/article/download/974/979 Coyote, Canis latrans,  Predation on a Bison,  Bison bison, Calf in Yellowstone National Park 2009 J.W. SHELDON, GREGORY REED,  A. CHEYENNE BURNETT, KEVIN LI,  and ROBERT L. CRABTREE Yellowstone Ecological Research Center,  2048 Analysis Drive, Bozeman, Montana 59718 USA;  Canadian Field-Naturalist 123(3): 260–261. In the Yellowstone ecosystem, Coyote spring/summer diet consists of small mammals and ungulate neonates, primarily American Elk calves (Cervus elaphus), but also Pronghorn (Antilocapra americana) calves and the fawns of Mule Deer (Odocoileus hemionus) and White-tailed Deer (O. virginianus) (Murie 1940; Gese and Grothe 1995; Gese et al. 1996). Bison (Bison bison) appear to be a rare food source for Coyotes. Murie’s (1940) analysis of 5086 Coyote scats showed a percentage occurrence of 0.20% Bison, and Murie found it unlikely that Coyotes would kill Bison calves, recording that anecdotal reports of the same “lacked proof”. Adult Bison chasing a Coyote More recently, a study of Coyote predation on large ungulates in Yellowstone found that both White-tailed Deer and Elk were killed by packs of Coyotes hunting together in winter (Gese and Grothe 1995).  No predation on Bison was recorded in either of these Yellowstone Coyote studies. Circumstantial evidence at kill sites in Yellowstone has suggested that predation on Bison calves by groups of Coyotes may occur, but no report has been published. Coyotes are opportunistic predators capable of killing ungulate prey, usually hunting in packs. However, Bison embody a formidable set of anti-predator adaptations, including well-developed maternal guarding behaviors (Carbyn and Trottier 1987, 1988), general herd behaviors of cow-calf groups, and size constraints that regulate prey acquisition by the relatively small framed and light-weight Coyote.  The cost of predation attempts on ungulate neonates is demonstrably high: an alpha female Coyote with pups in the den was killed during a predation attempt on an Elk calf (unpublished data; this study; 2005), with her post-mortem indicating blunt-force trauma as the cause of death. Certainly, predation attempts on ungulate neonates are a high risk activity for Coyotes. Notably, in eight out of nine predation attempts on large ungulate prey, the alpha male led the attack (Gese and Grothe 1995), as was also the case in our observation. In this instance, the stranding of the Bison calf was a causal factor leading to its death. The observed successful kill by a single adult male Coyote shows that predation on Bison calves may be possible under certain, albeit rare, conditions involving separation of a calf from its mother. It also shows that the size/weight limit of prey for adult Coyotes may be revised slightly upward.  The ecological context for the observed predation suggests that it may be part of a larger prey-switching phenomenon accompanying changes in spring use areas by ungulate prey, primarily Elk (Garrott et al. 2007). Our observation is of additional interest because theYellowstone ecological community embodies the southernmost outpost of an intact and functioning ungulate-predator system in North America, surrounded by areas of increasingly intensive human activity. --------------------------------------------------------------------

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Threat of predation: do ungulates behave aggressively towards different members of a coyote pack?

Eric M Gese; 1999

ABSTRACT

Wild ungulates have evolved a variety of antipredator strategies to deter or escape predation by carnivores. Among wild canids, the dominant pair of a pack often initiates attacks upon prey. Previous observations in Yellowstone National Park, Wyoming, showed that the alpha pair in a coyote (Canis latrans) pack most often leads attacks on ungulates during winter.

 We were interested in determining whether ungulates can distinguish (perhaps by body size or posture) which members of a coyote pack are the alpha individuals, and whether they initiate and direct aggressive behavior towards those members of the pack that pose the greatest threat of predation to themselves and (or) their offspring. During 2507 h of behavioral observations on 54 coyotes between January 1991 and June 1993, we observed 51 interactions between coyotes and adult elk (Cervus elaphus), bison (Bison bison), and pronghorn antelope (Antilocapra americana) in Yellowstone National Park.


Adult Bison starting down two Coyotes

 The interactions analyzed here are those in which the ungulate appeared to initiate aggressive behavior towards the coyote(s) and were not a response to an attack by the predators. We found that aggression by ungulates towards coyotes was highest during the summer months, when calves and fawns were present; female ungulates were more frequently aggressive than males.

 The frequency of aggression of adult ungulates towards small and large groups of coyotes was equal to the frequency of occurrence of these groups. Ungulates directed aggressive behavior more frequently towards alpha coyotes and were less aggressive towards beta coyotes and pups. Large ungulates, particularly elk and bison, appeared to perceive that alpha coyotes posed a greater threat to themselves and their offspring. The smaller ungulate, the pronghorn antelope, directed aggressive behavior equally towards all coyotes. Adult ungulates were probably responding to the larger body size of the alpha coyotes and the tendency of alpha coyotes to travel at the front of the pack.