Henry Mountains

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Bison population numbers on this unit are managed by sport harvest. This once in a lifetime permit provides a unique opportunity for sportsmen to take a bison in a truly wild situation. Hunting permits are set to maintain the population at or below the current population objective and sex ratio, in a combination of hunter choice, or cow-only permits. The first bison hunt on the Henry Mountains was held in 1950, when 10 permits were issued, and 6 bulls and 4 cows were harvested. Hunting resumed in 1960, and permits have issued every year since, with the exception of 1965, 1972 and 1973. Due to difficulties in sex determination, the permit was officially designated as Hunters Choice in 1974. The first cow-only permits were issued in 1988, and an orientation course is offered each year to teach permit holders how to properly distinguish cows from bulls. Non-resident permits, based on 10% of total permits, were first offered in 1978. Conservation permits, which are sold at an auction to the highest bidder, or by conservation groups at annual banquets, were first offered in 1982.

There have been over 1800 bison hunters afield from the first hunt in 1950 through 2005. Hunter choice permits have ranged from 9 in 1975, to 68 in 1991. The average number of hunter choice permits has been 26. There have been 564 cow-only hunters afield. Permit numbers have ranged from 0 in 1992, 1993 and 1996, to 129 in 1990. The average number of cow-only hunters has been 38. A total of 55 conservation permits 9 have been issued. Hunters have harvested 1611 bison, comprised of 890 bulls and 721 cows. The average annual harvest has been 21 bulls and 34 cows. Overall, hunter success has been 87%, while it has been 93% for hunter choice permits, and 77% for cow-only permits.

There continues to be a high demand for these unique permits. In 2005, 4336 residents applied for 19 permits, and 601 non-residents put in for 3 permits (Crump 2005). Overall odds of obtaining a permits was greater than 200 to 1. Of course, these odds are affected by the number of bonus points the applicant has, making odds less for some, and greater for others. The number of total applicants for bison permits on the Henry Mountains has increased by 461 since 2001.

This information has been retrieved from a 2007 report found here: https://wildlife.utah.gov/hunting/biggame/pdf/bison_15.pdf

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Habitat management practices include purchases of grazing allotments from willing sellers, operator conversion of domestic sheep grazing allotments to cattle to reduce the chance of disease transmission, vegetative treatments, and water developments. The Division and BLM have partnered in a program to create suitable bison habitat on the Henry Mountains. Efforts include rangeland prescribed burns, mechanical treatments and reseedings. The Division has funded such projects covering over 6,700 acres. Also, two wild fires occurred in 2003, encompassing over 34,000 acres, most of which were reseeded. The work dramatically increased the quality of habitat on the Henry Mountains for livestock, bison and mule deer. Conservation organizations are active in negotiating, funding, and participating in habitat enhancement projects.

On the Henry Mountains, bison have been very adaptable and utilized a wide variety of habitat types. The Henry Mountains herd has used grassland flats at just over 5000 feet in elevation on Blue Bench, pinyon-juniper woodlands and chainings from 5000 feet at Swap Mesa to over 8000 feet at McMillian Springs. Bison also use sub-alpine meadows at over 11,000 feet on Mount Ellen and Pennell. At times they prefer the shade of Douglas fir stands on the east side of Pennell during the summer, but they may also be found on the stark indian ricegrass/globemallow flats on Stevens Mesa during the hottest days of the year.

Disease

There are three diseases of major concern to bison in Utah, brucellosis, tuberculosis and malignant catarrhal fever.

Blood from hunter-harvested bison is tested annually for brucellosis. There have been no reactors since 1963 and the Henry Mountains bison herd is considered brucellosis free.

Tuberculosis, when found in conjunction with brucellosis, can affect the survival and reproductive capabilities of cow bison. No reactors were found among 12 yearlings tested before being transplanted to Arizona from the Henry Mountains in 2001. Bison are also susceptible to a related disease, paratuberculosis, or Johne’s disease. Johne’s is a viral infection that can have devastating effects on bison.

Malignant catarrhal fever (MCF) is the most serious viral disease affecting ranched bison. It is also known to affect other bovine species, domestic sheep and deer. Related to the herpes virus, it is transmitted through lacrimal, nasal, oral and vaginal secretions, but has occurred in other situations and direct contact is not necessary. Bison have contracted MCF from sheep grazed over 2 miles away (Haigh et. al. 2002). Wind-borne infections have been reported and deer contracted the disease after traveling in a truck that carried sheep with MCF.

Malignant catarrhal fever is invariably fatal. In the most extreme cases, the animal dies showing no clinical symptoms. Treatment of chronic cases is considered hopeless. There is no vaccine. Prevention requires that sheep or wildebeest do not have contact with susceptible species (Haigh et. al. 2002). It is recommended that domestic sheep herds not be grazed within two miles of bison to protect the population from MCF and Johne’s disease.

Genetics

The Henry Mountains herd is one of only four free roaming, genetically pure herds remaining on public lands in North America. It is recognized as a key population in maintaining the bison genome. The others include: Yellowstone National Park, Wind Cave National Park, and Elk Island in Alberta, Canada (Kunkel et. al. 2005). Additionally, the Henry Mountains herd is tested annually, and has been designated as >brucellosis free= since 1962.

Kunkel et.al. (2005) assessed management strategies for minimizing the potential negative effects of inbreeding, the goal being to maintain 90% of the genetic diversity of the gene pool over a 500-year period. They recommend that each population have at least 430 individuals, including both adults and young, to maintain a minimum viable population. This will ensure survival of the plains bison genome.

This information has been retrieved from a 2007 report found here: https://wildlife.utah.gov/hunting/biggame/pdf/bison_15.pdf

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This herd had its roots in Yellowstone National Park. In 1941, the Carbon Emery Wildlife Federation and the Utah State Department of Fish and Game obtained 18 bison, including 3 bulls and 15 cows, in a cooperative effort from the National Park Service. The animals were released near Robber’s Roost Ranch north of the Dirty Devil River on the San Rafael Desert (Nelson 1965). The majority of the animals established themselves near the release site, but a few dispersed to areas north and west, as far away as Ferron and the Strawberry Valley. Most of the dispersing animals were bulls, and it was deemed necessary to supplement the original reintroduction with an additional five bulls the next year. There have been no other introductions into this herd. These bulls joined the majority of the others and crossed the Dirty Devil River in 1942 onto the Burr Desert. These bison used the Burr Desert as winter range and the Henry Mountains as summer range from that time until 1962.

The population had grown to about 71 animals by 1962, when brucellosis was detected in the herd. In 1963, 69 bison were captured in a corral and tested and inoculated for brucellosis. Animals suspected of brucellosis infection were marked, then released and taken by sport hunters. A significant result of the harassment of the capture operation was a change in range used by the bison. Since 1963, the herd has utilized the Henry Mountains as its home range.

Current management practices include an annual helicopter survey, summer ground classification, sport harvest, and extensive habitat management. A population estimate is derived annually based on the number of animals counted during the survey, count conditions, ground classification, the number of animals harvested, and a 5% natural mortality rate.

Pre-season population estimates of the herd, including calves, have ranged from 59 in 1964, to 559 in 1990. The bull:cow ratio has ranged from a low of 37 bulls per 100 cows in 1986, to a high of 72 in 1983 (Table 1). The average from 1949 to 2006 was 53. The number of calves per 100 adults has averaged almost 25 over the same period, ranging from 8 in 2003, to 40 in 1950. The average number of calves per 100 cows has averaged 37, ranging from 17 in 2003, to 56 in 1962.

The average number of estimated adults, post-season, since 1984 has been 266, ranging from a high of 320 in 1990, to a low of 162 in 2005 (Table 2). Currently, the Henry Mountains herd numbers about 340 adults and calves, with a population objective of 275 adults, post-season. Due to drought and poor calf production, the population was in a downward trend, but has responded in recent years to increased precipitation and forage production.

This information has been retrieved from a 2007 report found here: https://wildlife.utah.gov/hunting/biggame/pdf/bison_15.pdf