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There is a common misconception that wild Mustangs have no natural predators. You've probably heard this claim before. It comes from a variety of places, but most obviously the Bureau of Land Management and the ranching industry. The idea that wild Mustangs have no natural predators couldn't be farther from the truth. Mustangs' predators include, but are not limited to, cougars (mountain lions), various species of bears (grizzlies, black bears), wolves, coyotes, etc. Unfortunately, all these predators are hunted by humans and many, such as bears and wolves, have been displaced by human development, thus they're prevented from doing their job efficiently.

Let's look at each major North American wild horse predator in depth:

WolvesWolves have the potential to be Mustangs' chief predator. In Canada, Mustangs are frequently preyed on by wolves. They are pack hunters, and while they are individually too small to bring down anything other than a foal or an old sick adult, a pack of them can easily bring down a healthy adult, even if a few pack members are injured or killed in the process. They also naturally roam in the same areas that Mustangs do: Northwest plains and sometimes mountainous regions. Here is one case of a healthy, mid to large-sized Quarter Horse that was brought down by wolves (warning, graphic images): www.skinnymoose.com/bbb/2011/0… . Unfortunately, wolves in the U.S. have had their population and habitat dramatically reduced due to human development. Thus, wolf territories today generally do not overlap with wild horse territories, even though they used to. This is what the National Academy of Sciences has to say about wolves and wild horses:
    Wolves are quite capable of preying on equids. In southern Europe, equids constituted 6.2 percent of wolf diets (range, 0-24 percent) (Meriggi and Lovari, 1996). In Abruzzo National Park, Italy, horses constituted 70 percent of wolf diets; however, unguarded horses are commonly hobbled in that area to prevent long-range movements (Patalano and Lovari, 1993, cited in Meriggi and Lovari, 1996). In northwestern Spain, a population of free-ranging ponies is heavily preyed on by wolves (Lagos and Barcena, 2012). Foal survival rate was very low (0.41), and 76 percent of foal carcasses found were killed by wolves. Van Duyne et al. (2009) reported that wild Przewalski’s horse foals were killed by wolves in Hustai National Park, Mongolia, and cautioned that predation could influence translocation efforts. However, those horses are sufficiently vigilant to survive and reproduce, so perhaps they have not lost essential skills (King and Gurnell, 2012). Wolves in a multiprey system have been reported to prey on feral horses in Alberta, Canada. Webb (2009) reported that one of 36 kills by wolves included a feral horse. Webb (2009) located 192 ungulates that had been killed by wolves in 11 packs from 2003 to 2006. Some 7 percent were feral horses, and they made up 12 percent of the total biomass consumed (0.01 ± 0.02 feral horse/pack per day). Despite evidence that wolves prey on equids elsewhere, the committee was unable to identify any examples of wolf predation on free-ranging equids in the United States.This is basically the same thing that I've said. Wolves are capable of hunting horses, even adult horses, but in the U.S., they do not live in many of their native habitats. Wild horses still live in those habitats, but wolves no longer do, thanks to human involvement. In essence, wild horses are having the same exact problem that deer are having. Whitetail deer are overpopulating because their natural predator, the wolf, has been displaced by humans. The gray wolf in North America is not endangered, but it can't do its job effectively.

Cougars / Pumas / Mountain LionsCougars alone kill about half of Mustang foals born every year and are currently Mustangs' chief natural predator in the U.S., although wolves would be more effective if they were allowed to do so. The reason cougars are not as effective as wolves is because cougar and wild horse habitats to not generally overlap. Cougars are called mountain lions for a reason: they live in the mountains (wow, didn't see that one coming!). Mustangs usually live on the plains and in desert areas. Some HMAs (Herd Management Areas) are in mountainous regions, and in those places, cougars do a pretty good job of keeping the wild horse population in check. Cougars enjoy horsemeat so much that they will often focus on hunting mainly horses to the near exclusion of other prey animals. Unfortunately, because cougars usually don't live on the open plains or in the desert, those Mustangs are rarely preyed on by cougars. The most common desert predator that poses any sort of threat to wild horses is the coyote, which I will cover later. Wolves live and hunt in open plains, but they've been pushed out of Mustang plains by human development (as I mentioned earlier). This is what the National Academy of Sciences has to say about cougars and wild horses:
    Most predation on free-ranging equids in North America has been attributed to mountain lions. That has been reported by Robinette et al. (1959) and Ashman et al. (1983). Berger (1983c) cited an unpublished report of 21 cases of mountain lion predation on free-ranging horses in the Great Basin; those deaths spanned more than 20 years and had negligible effects on population growth. Feral (but not free-ranging) horses constituted 11 percent of mountain lion diets in Alberta (Knopff and Boyce, 2009). Horses constituted 10-13 percent of adult male lion diets, but female lion diets were almost devoid of horses (Knopff et al., 2010). Overall, mountain lion predation on free-ranging equids in North America is, with few exceptions, considered uncommon (Berger, 1986).
    One of the exceptions is the free-ranging horse population on the central California-Nevada border. Turner et al. (1992) examined foal survival rates in the area (the Montgomery Pass Wild Horse Territory managed by the U.S. Forest Service) because there was a ban on mountain lion hunting in California and low hunting pressure in Nevada that led to a high density of mountain lions. The study was conducted from May 1986 to July 1991 by examining the horse and mountain lion populations and documenting deaths of horses. The average annual cohort of foals over the 5 years was 32. The annual survival rates were calculated for foals (0.27), yearlings (0.95), and adults (0.96). From 1987 to 1990, 48 foals were lost; 58 percent were located as carcasses and 82 percent of those were killed by mountain lions. The authors concluded that mountain lion predation had a substantial effect on the demography of that free-ranging horse population. The study was continued, and Turner and Morrison (2001) used 11 years of data (1987-1997) to examine again the influence of mountain lions on the horse population in Montgomery Pass Wild Horse Territory. Their results supported the earlier work of Turner et al. (1992): mountain lions were responsible for the deaths of 45 percent of the foals that were born. Mountain lion predation was also hypothesized as a major factor in limiting horse population growth in an area of southern Nevada where they use high-elevation forested habitats in summer (Greger and Romney, 1999). Those habitats are excellent for mountain lions because of their broken topography.

By and large, research that has addressed the question of predation on free-ranging equids in North America has been limited to anecdotal observations and a few published papers, but at the time of the committee’s review, studies at the University of Nevada, Reno, that should provide more quantitative data were under way. The work in several mountain ranges of western Nevada was examining predation by mountain lions in multi prey systems in which free-ranging horses had various densities. Diet data were being obtained by using information from GPS-collared mountain lions to investigate predation events; more than 700 predation events had been investigated as of June 2012. Ten of 13 collared mountain lions that had access to free-ranging horses regularly consumed horses as prey. Horses were documented to have been consumed as prey by collared mountain lions in eight mountain ranges throughout the study area in western Nevada (Virginia, Pah Rah, Fox, Lake, Wassuk, and Excelsior ranges and Virginia and Smoke Creek Mountains). Preliminary data suggest that in that study area, where free-ranging horses are available as prey, more than 50 percent of the diet of collared mountain lions is made up of horses when diet data on individual mountain lions are pooled. Preliminary results suggest that mountain lions in that multiprey system are generalists at the population level but that some diet specialization occurs at the individual level: some lions select for deer where horses are more abundant, and some select for horses to the near exclusion of other prey items where mule deer, bighorn sheep, and domestic animals are present. There is also some evidence that the magnitude of predation on horses by mountain lions may be related to the density of free-ranging horses, greater predation on horses occurring where densities of horses are higher (Andreasen, 2012).
    The potential for mountain lions to affect the sizes of populations of free-ranging horses in North America is limited by the fact that most HMAs are in areas that have few mountain lions. The ranges of mountain lions tend to be concentrated in forested areas and at higher elevations (Kertson et al., 2011) and in areas that have mountainous or otherwise broken topography with limited viewsheds. In contrast, many horse populations favor habitats that have more extensive viewsheds. Mountain lions are ambush predators and require habitats that provide opportunities for stalking or finding prey without being seen. Other predators, such as wolves, are more cursorial—capable of pursuing prey across open habitats.
    That a large predator, when abundant, can substantially influence the dynamics of free-ranging horses is not surprising inasmuch as black bears (Zager and Beecham, 2006), mountain lions (Wehausen, 1996), and other predators (Ballard et al., 2001; Boertje et al., 2010) have exerted strong influences on ungulate populations. However, the influence of predation on horses in the western United States is considerably limited by a lack of habitat overlap both with mountain lions and with wolves. Another constraint is that among free-ranging horse populations, foals are the usual prey, and predation on adults has rarely been documented until the recent studies in Nevada. Population size is not affected as much by foal survival as it is by adult survival (Eberhardt et al., 1982), and foal survival is strongly affected by other variables (such as weather).

BearsBears are more than capable of killing an adult horse...if they can catch it. A single bear has a good chance of bringing down even a healthy horse, but the problem here is that horses are generally too fast for bears to catch. Again, wolves are the best candidate, seeing as they can chase a horse(s) and run it down. However, if a bear is lucky enough to catch a wild horse unawares, the bear has a very good chance of having a meal.

CoyotesCoyotes typically prey on young or very sick horses. They share territory with Mustangs. Unfortunately, they aren't big enough to take on a healthy adult, unless they hunt in a very, very large pack, which isn't likely. Coyotes are not a main natural predator of Mustangs, although a pack of them could kill a foal or a very weak adult.

More information in the links below! This information is so basic that most of what I could find were websites aimed at tiny school children. Don't take it personally. It just goes to show how silly anti-Mustang people are that they actually need to be reminded of this stuff.
www.nap.edu/read/13511/chapter…

www.eduscapes.com/nature/musta…

www.whateats.com/what-eats-a-h…

wonderopolis.org/wonder/are-ho…

More Mustang comics:

Is the BLM insane? the-cynical-unicorn.deviantart…
Avoiding the question of whether or not to eradicate Mustangs: the-cynical-unicorn.deviantart…
The weak die, the strong survive...expect Mustangs: the-cynical-unicorn.deviantart…

Description

There is a common misconception that wild Mustangs have no natural predators. You've probably heard this claim before. It comes from a variety of places, but most obviously the Bureau of Land Management and the ranching industry. The idea that wild Mustangs have no natural predators couldn't be farther from the truth. Mustangs' predators include, but are not limited to, cougars (mountain lions), various species of bears (grizzlies, black bears), wolves, coyotes, etc. Unfortunately, all these predators are hunted by humans and many, such as bears and wolves, have been displaced by human development, thus they're prevented from doing their job efficiently.

Let's look at each major North American wild horse predator in depth:

WolvesWolves have the potential to be Mustangs' chief predator. In Canada, Mustangs are frequently preyed on by wolves. They are pack hunters, and while they are individually too small to bring down anything other than a foal or an old sick adult, a pack of them can easily bring down a healthy adult, even if a few pack members are injured or killed in the process. They also naturally roam in the same areas that Mustangs do: Northwest plains and sometimes mountainous regions. Here is one case of a healthy, mid to large-sized Quarter Horse that was brought down by wolves (warning, graphic images): www.skinnymoose.com/bbb/2011/0… . Unfortunately, wolves in the U.S. have had their population and habitat dramatically reduced due to human development. Thus, wolf territories today generally do not overlap with wild horse territories, even though they used to. This is what the National Academy of Sciences has to say about wolves and wild horses:
    Wolves are quite capable of preying on equids. In southern Europe, equids constituted 6.2 percent of wolf diets (range, 0-24 percent) (Meriggi and Lovari, 1996). In Abruzzo National Park, Italy, horses constituted 70 percent of wolf diets; however, unguarded horses are commonly hobbled in that area to prevent long-range movements (Patalano and Lovari, 1993, cited in Meriggi and Lovari, 1996). In northwestern Spain, a population of free-ranging ponies is heavily preyed on by wolves (Lagos and Barcena, 2012). Foal survival rate was very low (0.41), and 76 percent of foal carcasses found were killed by wolves. Van Duyne et al. (2009) reported that wild Przewalski’s horse foals were killed by wolves in Hustai National Park, Mongolia, and cautioned that predation could influence translocation efforts. However, those horses are sufficiently vigilant to survive and reproduce, so perhaps they have not lost essential skills (King and Gurnell, 2012). Wolves in a multiprey system have been reported to prey on feral horses in Alberta, Canada. Webb (2009) reported that one of 36 kills by wolves included a feral horse. Webb (2009) located 192 ungulates that had been killed by wolves in 11 packs from 2003 to 2006. Some 7 percent were feral horses, and they made up 12 percent of the total biomass consumed (0.01 ± 0.02 feral horse/pack per day). Despite evidence that wolves prey on equids elsewhere, the committee was unable to identify any examples of wolf predation on free-ranging equids in the United States.This is basically the same thing that I've said. Wolves are capable of hunting horses, even adult horses, but in the U.S., they do not live in many of their native habitats. Wild horses still live in those habitats, but wolves no longer do, thanks to human involvement. In essence, wild horses are having the same exact problem that deer are having. Whitetail deer are overpopulating because their natural predator, the wolf, has been displaced by humans. The gray wolf in North America is not endangered, but it can't do its job effectively.

Cougars / Pumas / Mountain LionsCougars alone kill about half of Mustang foals born every year and are currently Mustangs' chief natural predator in the U.S., although wolves would be more effective if they were allowed to do so. The reason cougars are not as effective as wolves is because cougar and wild horse habitats to not generally overlap. Cougars are called mountain lions for a reason: they live in the mountains (wow, didn't see that one coming!). Mustangs usually live on the plains and in desert areas. Some HMAs (Herd Management Areas) are in mountainous regions, and in those places, cougars do a pretty good job of keeping the wild horse population in check. Cougars enjoy horsemeat so much that they will often focus on hunting mainly horses to the near exclusion of other prey animals. Unfortunately, because cougars usually don't live on the open plains or in the desert, those Mustangs are rarely preyed on by cougars. The most common desert predator that poses any sort of threat to wild horses is the coyote, which I will cover later. Wolves live and hunt in open plains, but they've been pushed out of Mustang plains by human development (as I mentioned earlier). This is what the National Academy of Sciences has to say about cougars and wild horses:
    Most predation on free-ranging equids in North America has been attributed to mountain lions. That has been reported by Robinette et al. (1959) and Ashman et al. (1983). Berger (1983c) cited an unpublished report of 21 cases of mountain lion predation on free-ranging horses in the Great Basin; those deaths spanned more than 20 years and had negligible effects on population growth. Feral (but not free-ranging) horses constituted 11 percent of mountain lion diets in Alberta (Knopff and Boyce, 2009). Horses constituted 10-13 percent of adult male lion diets, but female lion diets were almost devoid of horses (Knopff et al., 2010). Overall, mountain lion predation on free-ranging equids in North America is, with few exceptions, considered uncommon (Berger, 1986).
    One of the exceptions is the free-ranging horse population on the central California-Nevada border. Turner et al. (1992) examined foal survival rates in the area (the Montgomery Pass Wild Horse Territory managed by the U.S. Forest Service) because there was a ban on mountain lion hunting in California and low hunting pressure in Nevada that led to a high density of mountain lions. The study was conducted from May 1986 to July 1991 by examining the horse and mountain lion populations and documenting deaths of horses. The average annual cohort of foals over the 5 years was 32. The annual survival rates were calculated for foals (0.27), yearlings (0.95), and adults (0.96). From 1987 to 1990, 48 foals were lost; 58 percent were located as carcasses and 82 percent of those were killed by mountain lions. The authors concluded that mountain lion predation had a substantial effect on the demography of that free-ranging horse population. The study was continued, and Turner and Morrison (2001) used 11 years of data (1987-1997) to examine again the influence of mountain lions on the horse population in Montgomery Pass Wild Horse Territory. Their results supported the earlier work of Turner et al. (1992): mountain lions were responsible for the deaths of 45 percent of the foals that were born. Mountain lion predation was also hypothesized as a major factor in limiting horse population growth in an area of southern Nevada where they use high-elevation forested habitats in summer (Greger and Romney, 1999). Those habitats are excellent for mountain lions because of their broken topography.

By and large, research that has addressed the question of predation on free-ranging equids in North America has been limited to anecdotal observations and a few published papers, but at the time of the committee’s review, studies at the University of Nevada, Reno, that should provide more quantitative data were under way. The work in several mountain ranges of western Nevada was examining predation by mountain lions in multi prey systems in which free-ranging horses had various densities. Diet data were being obtained by using information from GPS-collared mountain lions to investigate predation events; more than 700 predation events had been investigated as of June 2012. Ten of 13 collared mountain lions that had access to free-ranging horses regularly consumed horses as prey. Horses were documented to have been consumed as prey by collared mountain lions in eight mountain ranges throughout the study area in western Nevada (Virginia, Pah Rah, Fox, Lake, Wassuk, and Excelsior ranges and Virginia and Smoke Creek Mountains). Preliminary data suggest that in that study area, where free-ranging horses are available as prey, more than 50 percent of the diet of collared mountain lions is made up of horses when diet data on individual mountain lions are pooled. Preliminary results suggest that mountain lions in that multiprey system are generalists at the population level but that some diet specialization occurs at the individual level: some lions select for deer where horses are more abundant, and some select for horses to the near exclusion of other prey items where mule deer, bighorn sheep, and domestic animals are present. There is also some evidence that the magnitude of predation on horses by mountain lions may be related to the density of free-ranging horses, greater predation on horses occurring where densities of horses are higher (Andreasen, 2012).
    The potential for mountain lions to affect the sizes of populations of free-ranging horses in North America is limited by the fact that most HMAs are in areas that have few mountain lions. The ranges of mountain lions tend to be concentrated in forested areas and at higher elevations (Kertson et al., 2011) and in areas that have mountainous or otherwise broken topography with limited viewsheds. In contrast, many horse populations favor habitats that have more extensive viewsheds. Mountain lions are ambush predators and require habitats that provide opportunities for stalking or finding prey without being seen. Other predators, such as wolves, are more cursorial—capable of pursuing prey across open habitats.
    That a large predator, when abundant, can substantially influence the dynamics of free-ranging horses is not surprising inasmuch as black bears (Zager and Beecham, 2006), mountain lions (Wehausen, 1996), and other predators (Ballard et al., 2001; Boertje et al., 2010) have exerted strong influences on ungulate populations. However, the influence of predation on horses in the western United States is considerably limited by a lack of habitat overlap both with mountain lions and with wolves. Another constraint is that among free-ranging horse populations, foals are the usual prey, and predation on adults has rarely been documented until the recent studies in Nevada. Population size is not affected as much by foal survival as it is by adult survival (Eberhardt et al., 1982), and foal survival is strongly affected by other variables (such as weather).

BearsBears are more than capable of killing an adult horse...if they can catch it. A single bear has a good chance of bringing down even a healthy horse, but the problem here is that horses are generally too fast for bears to catch. Again, wolves are the best candidate, seeing as they can chase a horse(s) and run it down. However, if a bear is lucky enough to catch a wild horse unawares, the bear has a very good chance of having a meal.

CoyotesCoyotes typically prey on young or very sick horses. They share territory with Mustangs. Unfortunately, they aren't big enough to take on a healthy adult, unless they hunt in a very, very large pack, which isn't likely. Coyotes are not a main natural predator of Mustangs, although a pack of them could kill a foal or a very weak adult.

More information in the links below! This information is so basic that most of what I could find were websites aimed at tiny school children. Don't take it personally. It just goes to show how silly anti-Mustang people are that they actually need to be reminded of this stuff.
www.nap.edu/read/13511/chapter…

www.eduscapes.com/nature/musta…

www.whateats.com/what-eats-a-h…

wonderopolis.org/wonder/are-ho…

More Mustang comics:

Is the BLM insane? the-cynical-unicorn.deviantart…
Avoiding the question of whether or not to eradicate Mustangs: the-cynical-unicorn.deviantart…
The weak die, the strong survive...expect Mustangs: the-cynical-unicorn.deviantart…