An Overview of the Hook Lake Wood Bison Recovery Project: Where Have We Come From, Where are We Now, and Where We Would Like to Go?

John S. Nishi
Department of Resources, Wildlife & Economic Development
Government of the NWT
Fort Smith, NT Canada X0E 0P0

Brett T. Elkin
Department of Resources, Wildlife & Economic Development
Government of the NWT
Yellowknife, NT Canada X1A 3S8

Troy R. Ellsworth
Department of Resources, Wildlife & Economic Development
Government of the NWT
Fort Smith, NT Canada X0E 0P0

Greg A. Wilson
Department of Biological Sciences
University of Alberta
Edmonton, AB Canada T6G 2E9

Don W. Balsillie
Aboriginal Wildlife Harvesters' Committee
Box 1899
Fort Resolution, NT Canada X0E 0M0

Janna van Kessel
Department of Renewable Resources
University of Alberta
Edmonton, AB Canada T6G 2H1

The following article was originally presented at the International Bison Conference in Edmonton, Alberta in August 2000. The conference covered a wide array of bison topics including production, marketing, genetics, history and much more. This article has been reprinted with the permission of the IBC2000 Chairman.

Abstract

The Hook Lake Wood Bison Recovery Project (HLWBRP) is a wildlife conservation project run cooperatively between the Deninu Kue' First Nation, Fort Resolution Aboriginal Wildlife Harvesters' Committee, and the Government of the Northwest Territories, Canada. The overall objective of the HLWBRP is to establish a captive, disease-free herd of wood bison (Bison bison athabascae) from a wild herd infected with bovine tuberculosis (Mycobacterium bovis) and brucellosis (Brucella abortus), and use the captive herd as source stock to establish a disease-free wild population. Through the HLWBRP we are pursuing a phased approach to the long-term objectives of habitat management, disease eradication, genetic conservation, and recovery of wood bison in the Slave River Lowlands. We provide a synopsis of the northern bison disease issue, an overview of the rationale of HLWBRP, and a report on the progress of this pilot project. We also discuss the benefits and necessities of working within a co-management framework to achieve meaningful progress on a contentious wildlife management issue.

Keywords

Wood bison, wildlife conservation, co-management, bovine tuberculosis and brucellosis

Background

History of diseased bison issue in northern Canada

In the late 1890s wood bison (Bison bison athabascae) in northern Canada were on the brink of extinction, with only 150 to 500 animals remaining (Preble 1908, Soper 1941, Gates et al. 1992). In 1922, Wood Buffalo National Park (WBNP) was created to protect the remaining wood bison, which by that time had increased to ca. 1,500 (see Carbyn et al. 1993). However, translocation of 6,673 plains bison (B. b. bison) from National Buffalo Park in Wainwright, AB, to WBNP from 1925-1928 (Ogilvie 1979) effaced the preliminary recovery of wood bison and resulted in one of the most serious blunders in wildlife management in northern Canada (see MacEwan 1995). The translocation not only resulted in the transfer of plains bison genes to the remnant wood bison population (Wilson and Strobeck 1999), but also introduced two exotic bovine diseases into the northern ecosystem: tuberculosis[1] and brucellosis[2] (Fuller 1966).

Following the introduction of plains bison to WBNP, the number of animals increased rapidly, and by 1934 there were ca. 12,000 bison in the park. Bison numbers remained between 10,000 and 12,000 over the next 20 years (Carbyn et al. 1993). However, following drowning events due to spring floods in 1958 to 1961 (ca. 2,000 drowned) and then again in 1974 (ca. 3,000 drowned), the population declined. Also between 1962 and 1978, there were three documented anthrax outbreaks in WBNP bison. Since 1969, the WBNP bison population has declined steadily. During a recent survey in March 1999, Berguson (1999) observed 2137 bison within the boundaries of WBNP.

Tuberculosis was first recognized in a single WBNP bison in 1937 and in another in 1946 (Environmental Assessment Panel 1990), whereas brucellosis was first noted in 1956 (Fuller 1966). Both diseases have maintained enzootic proportions in WBNP bison; Joly and Messier's (2000) recent data on WBNP bison showed overall prevalence rates of 31% and 45% for brucellosis and tuberculosis respectively, which is consistent with prevalence data from Tessaro (1988) on bison tested between 1983-1985. Through the combined effect with wolf predation, bovine brucellosis and tuberculosis are hypothesized as playing key roles in the decline and persistent low densities of bison in WBNP (Gates 1993, Messier and Blyth 1996, but see Peterson 1991, McCormack 1992, Carbyn et al. 1993).

The Hook Lake wood bison herd

The Hook Lake (HL) wood bison herd is a diseased subpopulation (i.e., infected with bovine brucellosis and tuberculosis) of the greater WBNP bison metapopulation and occupies the Slave River Lowlands (SRL), northeast of WBNP and east of the Slave River (see Fig. 1). Early accounts show that bison occurred in the HL area during the late 1700s (Hearne 1795), but with the overall decline of wood bison in the late 1800s through to the early 1900s, bison to the east of the Slave River were either extirpated (Radford in Gates et al. 1992) or existed at extremely low density.

Within recent history, bison were first observed in the HL area in the 1940s. Following the increasing numbers of bison observed in the SRL in the 1940s, the Slave River Reserve was established to protect the bison and promote continued population growth (Bison Disease Task Force 1988). Numbers of bison grew from about 200 in 1949 (Fuller 1950) to 1,700 animals in 1971 (Rippen 1971). Reserve status was revoked in 1955, and hunting was allowed for General Hunting Licence holders (i.e., Aboriginal hunters) and NWT residents. Between 1959 and 1961 two licensed outfitters sold big game trophy hunts in the Hook Lake area, but following an outbreak of anthrax in 1962 all resident and non-resident sport hunts of bison in the Hook Lake area were stopped due to public health concerns (Bison Disease Task Force 1988, Deninoo Wildlife and Resources Committee 1991). In 1968, after several years without an anthrax outbreak, a quota of 25 bison was established for NWT residents. In 1970, another licensed outfitter was allocated 25 tags for sport hunts in the Hook Lake area (Bison Disease Task Force 1988). Hunting by Aboriginal people was unrestricted. Between 1969 and 1974, an average of 179 bison per year were hunted (Van Camp 1987). Since 1974 the HL herd has been declining, and since 1977 the herd has fluctuated at low densities between 200 and 500 animals (Van Camp and Calef 1987). Recent surveys in 1994, 1996, and 2000 (RWED unpublished data) resulted in 212, 478, and 283 animals observed in the HL area, respectively. Key factors that have been implicated for the decline and continuous low density of bison in the HL area are brucellosis and tuberculosis, wolf predation, habitat succession, and hunting (Reynolds and Hawley 1987, Chowns et al. 1998).

Where have we come from?

As early as 1953, there was some discussion by park administration of a plan to eliminate tuberculosis in WBNP by using the Canadian Air Force to eradicate all bison and then to repopulate with disease-free animals (Carbyn et al. 1993). In 1968 a five-year management plan was proposed to fence or eliminate all bison in WBNP so as to establish a herd free of tuberculosis and brucellosis through a test and slaughter regime (Novakowski and Choquette 1967). However, this plan was later rejected for a number of reasons including: economic cost; conflict with National Park objectives; practicality of locating and eliminating all bison outside of enclosures; local, national and international criticism; and resistance by people in Fort Smith and Fort Resolution on the loss of bison as a source of meat (Bison Disease Task Force 1988). Despite rejection of the 1968 plan, the continued need and recognition for a comprehensive disease management plan resulted in another plan in 1972. The emphasis of that management plan was to establish a large-scale anthrax vaccination program and to concomitantly determine migration patterns, document trends in distribution and abundance, and continue monitoring of brucellosis and tuberculosis prevalence rates. Five years later though, the 1972 Management Plan was cancelled mostly due to problems and questions regarding the feasibility and effectiveness of the anthrax vaccination program (Millette and Sturko 1977, Bison Disease Task Force 1988). Consequently, it was not until 1985 when the Canadian domestic cattle herd was declared brucellosis-free that attention was refocused on diseased bison in WBNP. In 1986, a multi-agency Steering Committee[3] was commissioned to explore options and to address two problems: 1) the risk of potential spreading of bovine tuberculosis and brucellosis from the diseased bison in and around WBNP to domestic livestock, to the Mackenzie bison herd (MBH) and to the human population; and 2) the risk of interbreeding between hybrid bison in and around WBNP with wood bison in the MBH (Bison Disease Task Force 1988, Environmental Assessment Panel 1990). This process led directly to a federally appointed Northern Diseased Bison Environmental Assessment Process from 1988 to 1990, which culminated in a recommendation to eradicate all existing free-ranging diseased bison in and around WBNP and to replace those herds with healthy wood bison (Environmental Assessment Panel 1990). This proposed action was met with conflicting mandates and perceptions, and opposing fundamental values of the interest groups involved (Gates et al. 1997), with strong public opposition mostly from the First Nations communities and environmental organizations. Two major concerns expressed during this process were the possible impairment of ecosystem integrity and the loss of genetic diversity represented by infected herds (Northern Buffalo Management Board 1992).

The only recommendation that was implemented following the Environmental Assessment Process was the creation of another Steering Committee to develop the terms of reference for the newly created Northern Buffalo Management Board (NBMB). The NBMB was comprised of nine Aboriginal members (representing Treaty 8 Bands in the Greater WBNP area), five-government seats, and three members from private organizations. In June 1991 the NBMB was mandated to develop a management plan to eradicate the two bovine diseases and to ensure the conservation of northern bison (NBMB 1992, Gates et al. 1997). After 18 months of intense, fractious and often political deliberations (Gates et al. 1997), the Board concluded that significant information gaps existed in the epidemiology of the two diseases, the ecological role of the diseases, and the possible effects of management action on other fundamental aspects of the ecosystem. It recommended that a three year research program budgeted at $18 million be conducted prior to the development of a final action plan (NBMB 1992).

In 1995, the federal government responded to recommendations of the Environmental Assessment Panel and of the NBMB by announcing a $2.5 million, five-year Bison Research and Containment Program (BRCP). The BRCP's three main components were risk assessment, disease containment, and ecological research (Chisholm et al. 1998, Huff and Chisholm 1999). The Minister of Canadian Heritage appointed a multi-stakeholder Research Advisory Committee (RAC)[4] to advise Parks Canada on the planning, implementation, and evaluation of bison research, with the objective that the research would form the basis for a realistic, ecologically-sound and knowledge-based (including scientific and Aboriginal traditional knowledge) management plan for bison (Chisholm et al. 1998). To date, the BRCP has funded one major study on the population level effects of tuberculosis and brucellosis on WBNP bison (see Joly and Messier 2000).

Community planning and the early vision

The annual range of the Hook Lake herd falls within the traditional hunting area of the community of Fort Resolution, and therefore represents an important wildlife resource for the community. With the failure of the Federal Environmental Assessment and Review Process as an important impetus, Fort Resolution drafted the Hook Lake Wood Bison Management Plan in July 1991 (Deninoo Wildlife and Resources Committee 1991). That community-based plan outlined five goals over a 10-year period: 1) restore a healthy herd of wood bison to the Hook Lake area; 2) preserve the genetic integrity of the Hook Lake wood bison; 3) salvage existing healthy bison from the Hook Lake area; 4) preserve and enhance the Hook Lake ecosystem; and 5) explore and recognize potential commercial opportunities for the Hook Lake wood bison herd. The plan's approach was based on construction of a system of corrals and compounds, centrally located in the Hook Lake bison range, from which an extensive program of testing, culling, quarantine, and salvage would be conducted. Additional wood bison would be acquired from the Mackenzie bison herd and/or Elk Island National Park to carry out an extensive breeding program. Other objectives of the plan were to implement a range enhancement program and to also ensure a continuous supply of bison meat for the community of Fort Resolution.

In 1996, following the announcement of Wood Buffalo National Park's Bison Research and Containment Program, the Deninu Kue' First Nation, Fort Resolution Aboriginal Wildlife Harvesters' Committee (AWHC)[5] and Government of the Northwest Territories implemented an alternative approach to continued research. This pilot project - the Hook Lake Wood Bison Recovery Project (HLWBRP) - was largely based on the 1991 management plan objectives (Deninoo Wildlife and Resources Committee 1991). The HLWBRP comprised a phased approach to disease eradication, genetic conservation, and to the recovery and re-establishment of a healthy wood bison herd in the Hook Lake area. Overall project objectives were outlined according to four phases: 1) habitat enhancement (see Chowns et al. 1998); 2) genetic salvage and captive breeding; 3) range isolation; and 4) recovery. In the remainder of this paper we report primarily on our activities under phase two, and briefly discuss future options outlined in phases three and four.

Where are we now?

Specific objectives for the genetic salvage and captive breeding of Hook Lake wood bison are to: 1) conserve genetic integrity of the wild herd by capturing an adequate number of bison calves; 2) provide veterinary care and preventative drug treatment to eliminate tuberculosis and brucellosis from the captive calves; and 3) raise a disease-free herd of captive wood bison from the salvaged calves.

Capture and prophylactic treatment of wild-caught calves

We captured HL wood bison calves (estimated age from 1 to 10 days old) in May of three consecutive years (1996, 1997 and 1998) by netting them from a helicopter. In May 1996, we captured a total of 20 calves (6 males and 14 females) and brought them back to the Fred Dawson Isolation Facility at Fort Resolution, NT. During the subsequent two capture sessions in 1997 and 1998, we used the Brewer's Card Test (BCT) to test calves in the field for antibodies to B. abortus. All BCT positive reactors were returned to their site of capture and released within ca. 30 minutes of capture, whereas test negative calves were transported to the isolation facility for prophylactic treatment and hand-rearing. In May 1997, we captured and handled a total of 27 calves; 6 positive reactors and 1 negative reactor (male) were returned back into the field and the remaining 20 (4 males and 16 females) were forwarded on to isolation. In May 1998, we handled a total of 28 calves upon which 6 BCT positive calves were released back into the wild. We transported the remaining 22 BCT negative calves (6 males and 16 females) back to the isolation facility.

We housed each cohort of calves as isolated pairs in 1.3 m x 2.5-m wooden sheds for their first two weeks of captivity. During this period calves were habituated to people, trained to feed from a bottle, and treated with antibiotics via intramuscular injection (see Table 1). Calves habituated quickly and within 24 hours of capture, all calves, with a few exceptions, began feeding readily from the bottle. After the initial two-week period, we released calves as isolated pairs into larger 13 m x 23-m isolation paddocks. These paddocks were double-fenced to prevent direct contact between adjacent calf pairs. The double-fences were also lined by plastic tarps (in 1999 tarps were replaced by plywood) to act as a solid visual barrier and reduce direct airflow between adjacent paddocks. Additional disease control measures put in place included the use of protective clothing by handlers, disinfectant boot baths, and restrictions on movement into and between isolation pens.

During their first two days in captivity, we fed calves a colostrum replacement only. We then offered the colostrum in combination with a milk replacer for up to the next two weeks after which colostrum was discontinued. In 1996, we gave 10 calves frozen dairy colostrum and gave the other 10 calves the colostrum replacer HeadstartÔ (Chelack et al. 1993). Since we did not observe scouring problems in calves fed HeadstartÔ and the dried powder was easier to store and prepare, we used HeadstartÔ as the colostrum replacer for both the 1997 and 1998 calf cohorts. We used a standard reconstituted milk replacer for beef calves as the primary food source for young bottle-fed bison calves (powdered milk composition of 24% protein and 22% fat by weight, purchased from Brown's Feeds, Clive, AB). The milk replacer was offered to calves for four to five months and served as the medium for administering oral antibiotics (see Tables 1 and 3). We also offered calves a high quality alfalfa-timothy hay and after ca. four weeks of age, we also offered a medication-free calf starter (Champion Feed Services 18% Protein Calf Starter Grower) ad libitum throughout the isolation period. When calves were about 5 months of age, we replaced the calf starter with rolled barley at a rate of ca. 1 kg / calf / day.

The antibiotic protocol and prescribed dosages are summarized in Table 1, while duration of treatment is shown in Table 2. Gates et al. (1998) provides a discussion on the drugs used and the rationale for their selection. Major differences in drug protocol over the three-year hand-rearing period were as follows: 1) enroflaxacin (BaytrilÒ; Bayer Inc., Etobicoke, ON) was used as a liquid preparation in 1996 versus tablets in 1997 and 1998; 2) rifampin (RofactÒ; ICN Canada Ltd., Montreal, PQ) was administered in 1997 and 1998 but not in 1996; 3) oxytetracycline (Liquamycin LA-200Ò; Rogar/STB Inc., London, ON) was administered daily in the milk replacer in 1998, and 4) in 1998, the duration for administration of isoniazid (pms-INHÒ; Pharmascience, Montreal, PQ) was reduced, while durations for enrofloxacin and rifampin were increased.

For determination of initial drug dosages in 1996, we estimated calf weights at capture because a scale was unavailable. In 1997 and 1998, we weighed calves within 24 hrs of capture using an electronic scale. For comparative purposes, we used a linear regression between chest girth (cm) and body mass (kg) to determine initial weights of calves captured in 1996 (Table 3).

[1] Bovine tuberculosis is a disease caused by infection with the bacterium Mycobacterium bovis. Infected animals shed the bacteria in body secretions and transmission is usually through direct contact via inhalation of droplets expelled by infected animals or consumption of contaminated feed. Transmission may also occur from mother to fetus through the placenta and umbilicus, or when the newborn offspring consumes its mother's infectious milk. Bovine tuberculosis is a chronic and progressively debilitating disease that may effect the respiratory, digestive, urinary, nervous, skeletal, and reproductive systems (Environmental Assessment Panel 1990). The disease may reduce fertility, weaken infected animals and predispose them to predation, and in advanced cases result in death. Fuller (1966) and Tessaro (1998) estimated that advanced tuberculosis may result in 4-6% mortality in bison; both authors suggested a link between infection with tuberculosis and increased susceptibility to predation by wolves. Domestic cattle and bison are the main species affected by the disease although other species are susceptible (Schmitt et al. 1997, Bell 1999). Humans may be infected with bovine tuberculosis; the most likely route of infection being accidental inoculation of cuts and abrasions on hands while field dressing an infected bison carcass (Tessaro 1989).

[2] Bovine brucellosis is a disease caused by infection with the bacterium Brucella abortus and primarily involves the reproductive organs. In female bison brucellosis results in premature abortions, retained placenta, or weak calves that die soon after birth, infertility, and uterine infections. In males, the disease causes inflammation of the testes and epididymides (Tessaro 1988, Williams et al. 1997). The disease may also cause arthritis and hygroma in which inflammation of leg joints may be severe enough to result in crippling or increased susceptibility to predation (Tessaro 1988). The bacterium is shed in high concentrations by infected females during abortion or parturition and is found in placental and uterine fluids. Transmission is primarily through direct contact with infectious uterine fluids, aborted fetuses, or food, water, or soil contaminated by those materials; calves may become infected through ingestion of infected milk from its mother (Williams et al. 1997). Breeding males can transmit the disease through their semen during mating. In North America, domestic cattle, bison, and wapiti (Cervus elaphus) are the main host species for bovine brucellosis. Bovine brucellosis is infectious to humans. The most likely route of infection for hunters is accidental transmission of the bacteria through cuts and abrasions in the skin upon contact with the carcass, blood, or other body secretions during field dressing of an infected bison carcass (Tessaro 1989, Young and Nicoletti 1997).

[3] The original Steering Committee was comprised of representatives from Canadian Parks Service and Agriculture Canada. Other agencies, including the Government of the Northwest Territories Department of Renewable Resources, Canadian Wildlife Service, Health and Welfare Canada, Alberta Agriculture, and the Alberta Forestry, Lands and Wildlife Department, were invited and participated in later meetings.

[4] The RAC is comprised of representatives of four Aboriginal communities/First Nations, scientific representatives of the Governments of Alberta and the Northwest Territories, a representative of environmental non-government organizations, and a senior scientist from the United States National Park Service.

[5] The AWHC is a sub-committee of the Deninu Kue' First Nation and officially represents the interest of all aboriginal wildlife harvesters in the community of Fort Resolution. It is comprised of representatives of Treaty 8, the Fort Resolution Metis Local, the Elders Committee, and the Fort Resolution National Park Users Committee. The purpose of the AHWC is to support and promote the participation of aboriginal harvesters in all possible aspects of the renewable resource sector, including harvesting, development activities, research and management.

Table 1. Prescribed antibiotic treatment protocol for wild-caught bison calves potentially exposed to bovine tuberculosis and brucellosis (from Gates et al. 1998).

Antibiotic	Route of Administration*	Dosage	Duration of treatment**
Dihydrostreptomycin	IM	25mg/kg	EOD over 2 weeks
Oxytetracycline***	IM	25mg/kg	EOD over 2 weeks
Enrofloxacin	PO	10mg/kg	Daily for 3 months
Isoniazid	PO	10mg/kg	Daily for 5 months
Rifampin****	PO	10mg/kg	Daily for 3 months
* IM = intramuscular injection; PO = per os¸oral administration with milk ** EOD = Every other day *** In 1998, oxytetracycline was administered PO every day for 7 days **** Administered in 1997 and 1998, but not in 1996.

Capture Year  (Median Date)		1996 (12 May 1996)		1997 (11 May 1997)		1998 (5 May 1998)
Capture Period		5 days		3 days		2 days
Colostrum Replacer		13 days		12 days		8 days
Milk Replacer		5.3 months		5.5 months		4.1 months
Diydrostremtomycin		11 days		14 days		15 days
Oxytetracycline		11 days		14 days		7 days
Enrofloxacin		1.3 months		1.5 months		3.2 months
Isoniazid		4.9 months		5.3 months		3.7 months
Rifampin		-		1.5 months		2.8 months

 

			1996*				1997				1998
		Male (3)	Female (14)	All (17)		Male (4)	Female (16)	All (20)		Male (6)	Female (16)	All (22)
Body Mass (kg)		50.30	44.35	47.32ab		48.89	47.03	47.95a		44.07	40.31	42.19b
Standard Error		3.92	1.81	2.16		3.39	1.70	1.90		2.77	1.70	1.62

 

*We determined calf weights in 1996 derived from a linear regression between chest girth and body mass in wild-caught calves from 1997, 1998, and from captive born calves in 1999 and 2000. Data on captive-born calf weights and chest girth were collected at three days of age. The regression equation was applied to bison calves that had a chest girth ranging from 75 to 105 cm where:

Body mass (kg) = 1.159 *Chest Girth (cm) - 61.742, R2 = 0.81, P<0.0001, N = 60

Note: Sample sizes shown in parentheses. Body mass values with different superscripts denote significantly different mean values at P<0.05

Although male calves were consistently larger than female calves over all three years, the differences were not statistically significant (Table 3). This was likely a function of the small number of males we captured in any given year. However, we did observe significant differences between the average size of calves caught between years, with calves from the 1998 cohort being the smallest (Table 3). This difference was likely due to the timing of each of the spring captures; in 1998 we captured calves close to one week earlier than in the previous two years (Table 2).

Disease testing

Our basic disease-testing regime is comprised of two whole-herd tests conducted twice annually in the months of February and November. To test for exposure to bovine tuberculosis, we employ the intradermal caudal fold test using M. bovis PPD (tuberculin). In the event of positive or suspicious reactors the comparative cervical test is used to discriminate between reactors to M. bovis versus M. avium. For bovine brucellosis, Agriculture and Agri-Food Canada's Animal Disease Research Institute in Lethbridge, AB, conducts the following assays on blood serum: Buffered Plate Antigen Test (BPAT), Standard Tube Agglutination Test (STAT), and the Compliment Fixation Test (CFT). The Brewer's Card Test is also conducted on site during all test periods. All whole-herd tests are conducted with a veterinarian accredited by the Canadian Food Inspection Agency (CFIA).

Throughout our course of preventative treatment of wild-caught calves for bovine tuberculosis and brucellosis with antibiotics, we maintained all calves in pairs under strict isolation during their first 10 months. Our criteria for release of calf pairs into a larger cohort herd was that each individual calf had to test negative on two successive disease tests conducted at least 60 days apart. We conducted the first whole-herd test on the 1996 calf cohort in November 1996; all tests conducted were negative. During the second whole-herd test in February 1997, one female calf (Y33) reacted to the caudal fold test for tuberculosis. A swelling >10 mm was observed and palpated at the injection site, but due to logistical constraints, a comparative cervical test could not be conducted within the 10 day interval following tuberculin injection. As a precautionary measure, that female calf and its penmate were slaughtered (Gates et al. 1998) on 5 March 1997. The subsequent post-mortem on both calves found no gross visible lesions suggestive of infectious diseases. Histopathological observations determined that acid fast bacteria were present in a single minute granulomatous lesion in a mediastinal lymph node of the reactor calf, but laboratory culture by CFIA did not isolate any Mycobacterial species (Gates et al. 1998, B. Elkin unpub. data). Due to this one reactor calf, all calf pairs were kept in isolation until another whole-herd test was conducted on the cohort in April 1997. During the April 1997 disease test, one male (Y31) produced a suspicious reaction on the BCT and STAT tests for brucellosis, but tested negative on both the BPAT and CFT (Gates et al. 1998). That calf and its penmate were kept in isolation and re-tested on 25 June 1997, with negative results on all 4 tests. The remaining sixteen bison remained test-negative and were released to a common pasture on 29 April 1997. In subsequent years, we completed the disease-testing process for the 1997 and 1998 cohorts with all bison cohorts testing negative. Whole-herd tests completed to date are summarized in Table 4.

Table 4. Summary of whole-herd disease tests conducted on wild-caught bison at Fred Dawson Isolation Facility, Hook Lake Wood Bison Recovery Project, Fort Resolution, NT, as at November 2000.
Calf Cohort	No. of Whole-Herd Disease Tests
1996	10
1997	7
1998	5

 

We have embarked on a process of establishing a disease-free captive-breeding herd of bison with wild-caught calves from the disease-exposed Hook Lake herd using a combination of several techniques. These include: 1) capturing calves as soon as possible after birth ("orphaning") to minimize exposure to bovine brucellosis and tuberculosis (calves were 1- 10 days old when captured); 2) testing calves for brucellosis in the field before they are brought to the isolation facility in Fort Resolution (calves were tested in the field in 1997 and 1998 but not in 1996); 3) isolating calves in pairs to prevent spread of disease; 4) applying a prophylactic treatment of calves using anti-mycobacterial and anti-Brucella drugs; and 5) frequent testing and removal of reactor animals. Another important part of this process is the management of risk associated with latent infections of B. abortus.

Brucella abortus may produce latent infections in bison calves in utero (Plommet et al. 1973, Davis et al. 1990, Williams et al. 1993), or through direct oral exposure to the organism (Williams et al. 1997) such as transmission via milk from the nursing dam (Meyer and Meagher 1995). In bovine calves, these persistent infections are difficult to detect by serological tests, and females may test negative until their first calving or abortion and seroconvert thereafter (Sutherland and Searson 1990). For males, seroconversion may occur later in life (Rankin 1965).

To minimize risk of disease exposure to other animals in the herd, we physically isolate wild-caught females in isolation pens during the last trimester of their first pregnancy when brucellosis-induced abortions would mostly likely occur. We sample serum and test the cow and newborn calf at both 3 days and 4 weeks post-calving to look for possible seroconversion of latent Brucella infections. In the event of a latent infection, we would expect that the paired serum samples would show a postparturient rise in antibodies in the dam and a rise in maternal antibodies in the calf. While antibodies in the dam may remain elevated, calves born to infected dams have high serologic titres that fall to undetectable levels within 4-6 weeks of birth (Sutherland and Searson 1990). When possible, we also collect the placenta to confirm, through bacteriology, that a cow has not shed B. abortus during parturition. The cow and calf are released into the larger herd following negative results on both test occasions. We are optimistic that once every wild-caught female in all three cohorts has calved and successfully completed the post-calving brucellosis test, we will be able to establish disease-free status for the captive herd. At the time of writing, all 13 female bison from the 1996 cohort and 10 of 12 pregnant heifers from the 1997 cohort have had a live calf and tested negative on the 3-day and 4-week post calving brucellosis tests.

Captive breeding

With the final capture of 22 wild bison calves in May 1998 and four mortalities since the beginning of the project, the captive herd now consists of 58 founders in three separate cohorts (Table 5). In 1999, 9 of 13 females (69% pregnancy rate) from the 1996 cohort produced the first captive-born calves (Table 6). Calving occurred over a wide temporal window with the first calf born on 29 May and the last calf born on 5 October (Fig. 2). In comparison, calving in 2000 has been more synchronous with over 90% of calves born by late June (Fig. 2). In 2000 the pregnancy rate for the 1996 cohort of females (calving as 4-yr-olds) was 100%, and the pregnancy rate for the 1997 cohort (calving as 3-yr-olds) was 75%. Causes of mortality in captive-born calves have been variable (Table 6). Because of a case of nutritional myopathy in a female calf in 1999, we now preventatively treat pregnant cows with selenium/vitamin E in February, and treat calves born in isolation at three days of age.

Table 5. Current number of founder bison at Fred Dawson Isolation Facility, Fort Resolution, NT, August 2000. Numbers in brackets represent mortalities.
Calf Cohort	Male	Female
1996 (4 Years old):	5 (1)	13 (1)*
1997 (3 Years old):	4 (0)	16 (0)
1998 (2 Years old):	6 (0)	14 (2)**
SUM	15 (1)	43 (3)
* Female bison (Y33) reacted on caudal fold test. Y33 and male penmate (Y43) killed on 5 March 1997 for post mortem examination (see text). ** Female calf (Y79) euthanized on 15 August 1998 due to severe ataxia and after 3.5 months of unsuccessful treatment (culture negative for tuberculosis and brucellosis). Female short yearling (Y117) died on 12 April 1999 because of accidental neck injury.

Table 6. Calves born in captivity at the Hook Lake Wood Bison Recovery Project, Fort Resolution, NT. Numbers in brackets indicate calf mortalities*.
Calf Cohort	Male	Female
1999	3 (0)	4 (2)
2000	10 (2)	11 (2)
Sum	13 (2)	15 (4)
*1999 mortalities: Nutritional myopathy; unknown 2000 mortalities: Late term abortion (non-disease related), stillborn (hypoxia resulting from dystocia), trauma (kicked in head), mortality due to unknown cause

Conservation genetics

Ongoing work on 11 microsatellite markers in bison (see Wilson and Strobeck 1999) shows that with the current number of founders, the HLWBRP has established the most genetically variable wood bison herd that has been salvaged from WBNP (G. Wilson unpub. data). However, captive bison in the HLWBRP, Mackenzie herd (Fig. 1), and Elk Island National Park are all less variable than WBNP. Wood bison populations are genetically distinct from each other with WBNP being most similar to bison in the HLWBRP. This is again due to HLWBRP's large founding sample size and the small amount of time that genetic drift has had to change the allele frequencies in this population. Ideally, future salvage attempts will use sample sizes at least as large as that for HLWBRP to obtain a representative sample of the genetic variation in their founding population. Through ongoing collaboration with the University of Alberta we are determining the extent that genetic variability in the wild HL subpopulation is represented in the HLWBRP founders. In addition, we are also determining parentage in captive-born calves, potential relationships among the HLWBRP founders, and investigating strategies for optimum conservation of genetic diversity.

Where we would like to go
Disease-free status

In order to pursue the long-term goal of establishing a healthy wild herd of wood bison - free from bovine tuberculosis and brucellosis - back in the Hook Lake range, our most critical short-term objective is to establish disease-free status for the captive HLWBRP herd. Given our progress and status to date, we are optimistic that disease-free status is achievable once all wild-caught female bison have calved and tested negative for brucellosis. The process by which we plan to establish disease-free status will necessarily require the continued input and support of both the scientific community (i.e., National Wood Bison Recovery Team) and the animal health agencies (i.e., Canadian Food Inspection Agency) that have the expertise and mandate to monitor health status and to regulate movement of captive ungulates. To this end, we plan to collaborate with the Animal Health Risk Assessment Unit of the Canadian Food Inspection Agency to initiate a quantitative assessment of the health status of our captive herd.

Although there have been two prior salvage operations that have established disease-free wood bison herds from founders captured from WBNP, i.e., the Mackenzie wood bison herd and Elk Island National Park wood bison herd, the criteria by which disease-free status was achieved are not well defined. However recent efforts by the Greater Yellowstone Interagency Brucellosis Committee (GYIBC) to define quarantine and testing requirements for qualifying brucellosis-exposed bison from Yellowstone and Grand Teton National Parks as brucellosis free, serves as a useful example (Greater Yellowstone Interagency Brucellosis Committee 2000). Our hope is to define the criteria and help outline a policy framework that will support this wood bison recovery and disease eradication project and others like it in the future.

Community consultation and options for the future

Through its initial vision and ongoing participation in the HLWBRP, the community of Fort Resolution has shown leadership in providing future options to resolving a contentious wildlife management issue. Success to date lies largely in the fact that this project has been collaborative and co-managed between the community and the Government of the Northwest Territories from the outset. Yet as we approach the short-term objective of disease-free status over the next years, it is increasingly important to consider options and plan for the future. The fundamental requirement for this planning is community consultation. Through an extensive interview process with a representative sample of people in Fort Resolution, van Kessel (unpub. data) has initiated a qualitative research project that will document local and traditional Aboriginal knowledge of the history, management, and cultural importance of wood bison. We plan to use this work as the first step towards a better understanding of the community's perceptions and opinions on the northern diseased wood bison and to help confirm and refine the future direction and management of the Hook Lake Wood Bison Recovery Project.

At a minimum, reestablishment of a healthy herd of bison in the Hook Lake range will ultimately require removal of disease-exposed wild bison, reintroduction of disease-free animals, and isolation (i.e., double-fenced perimeter) and active surveillance to ensure that the reintroduced animals are not re-exposed to bovine brucellosis and tuberculosis. The risk for re-exposure is a direct result of diseased free-ranging bison reinhabiting or emigrating to the HL range. Although the Hook Lake and Little Buffalo River herds (see Fig. 1) have been described as discrete subpopulations based on early distribution studies (Calef 1976, Calef and Van Camp 1987), the risk of transmission of either brucellosis or tuberculosis is likely high enough, from an epidemiological perspective, to consider the distribution linked across the Slave River and continuous with WBNP. The rationale behind this perspective is threefold. Firstly, local hunters describe crossing areas used by bison across the Slave River (D. Balsillie pers. comm.). Secondly, successive years of aerial survey data (GNWT and Parks Canada unpub. data) have documented distribution and abundance of bison that indirectly accounts for movement of bison across the Slave River. And most recently, a 4-year-old bison bull (test positive for brucellosis, test negative for tuberculosis) that was captured in February 1999 near the Hornady River in WBNP was recaptured a year later ca. 15 km south-southwest of Hook Lake, approximately 140 km from its capture location (Joly and Messier unpub. data). Clearly, these occurrences show that careful planning for the next phases in the HLWBRP is essential. But more importantly, it also shows that the implications of diseased-bison in WBNP extend well beyond its political borders and may severely constrain options for bison recovery in the Hook Lake area - an area of traditional use by the community of Fort Resolution.

Summary

Within the history of wildlife management in the NWT, the northern diseased bison issue has been a long-standing contentious issue with a multitude of stakeholders ranging from local Aboriginal communities, to territorial/provincial and federal government departments, to the environmental and agricultural lobby in Canada as a whole. The Hook Lake Wood Bison Recovery Project was implemented in 1996, and it represents a major undertaking on behalf of the community of Fort Resolution and the Government of the Northwest Territories. The project is innovative because the approach to disease eradication involves the capture, isolation, and prophylactic treatment of young calves from a known disease-exposed population of wild wood bison. Captured calves are paired and hand-raised in isolation at a captive breeding facility, treated for brucellosis and tuberculosis using antibiotics, and subject to an intensive testing protocol that includes bi-annual whole herd tests and post-calving brucellosis testing. The project has been successful to date. The number of founders used to establish this captive herd represents more genetic diversity than two previous attempts to conserve wood bison from WBNP, and there have been no confirmed clinical cases of tuberculosis or brucellosis in the captive herd, suggesting that disease-free status is an achievable goal. Success to date has been largely a function of the collaborative nature of this project and the steadfast vision and support of the local community. To achieve its long term objective of reestablishing a healthy herd of wild wood bison in the Hook Lake area, the HLWBRP will not only require continued consultation and planning with the local community and its Aboriginal Wildlife Harvesters' Committee, but the project will require support from stakeholders at the territorial, regional, and national levels.

Fig. 1. Distribution of bison herds in northern Canada. Bison herds considered to be infected with bovine tuberculosis and brucellosis are shown by cross hashing: HL = Hook Lake, LBR = Little Buffalo River, NL = Needle Lake, PL = Pine Lake, GR = Garden River, PD = Peace Athabasca Delta, FB = Firebag, WZ = Wentzel, WA = Wabasca, BM = Birch Mountains. Bison herds considered to be disease-free are shown in dark grey: MB = Mackenzie, NH = Nahanni, PM = Pink Mountain, HZ = Hay Zama, SY = Syncrude/Fort McKay.

Fig. 2. Timing of bison calves born in captivity at the Hook Lake Wood Bison Recovery Project, Fort Resolution, NT, in 1999 (n = 9) and 2000 (n = 24). Arrows indicate mean dates of calving.

Acknowledgements

A long-term project of this scope requires the commitment and collaboration of many individuals. Initial plans for the recovery of Hook Lake wood bison owe a great deal to the vision of Tom Unka and Ron Boucher. Danny Beaulieu and Dr. Cormack Gates were instrumental in acting on that vision and initiating the project. The community of Fort Resolution, the Deninu Kue' First Nation, and the Aboriginal Wildlife Harvesters' Committee have been instrumental in generating the support and acceptance for this project. We gratefully acknowledge the dedication and hard work of Ken Delorme who replaced Robert Sayine in 1998 as project herdsman. Raymond King's keen interest and ready assistance are acknowledged as well as Steven Cuthbert's administrative prowess. Fred Mandeville, Lawrence Fabian, and Fire Crews G and H have assisted with various construction projects at the isolation facility. We acknowledge the energy and enthusiasm of all of our volunteers and summer students who have contributed immensely to this project. Kara Lascola, Jason Reeder, Charlotte Tees, Jennifer Neufeld, Dr. Darren Ludbrook, Dr. Todd Shury, Tiffany Wolf, Sarah Lightfoot, Jon Mitchell, Marnie Cooper, Denise Lowing, and Jody Bennett, have assisted at various times over two seasons of calving and disease-testing. Many individuals assisted with veterinary care and raising neonates especially Josie Unka, Cheryl Wray, Dr. Susan Kutz, Dr. Helen Schwantje, Dr. Bill Karesh, Holly Beaulieu, Joanne Malmgren, Suzanne Boucher, Joe Dragon, Judy Dragon, Mika Sutherland, Lois Philipp, Daniel Beaulieu Jr., Gene Hachey, Lisa Unka, Rick Rowel, Meredith Seabrooke, Stephanie Irlbacher, Joanna Wilson, Zelda Matthee, Barb Deyelle, Sarah Green, Wade Comin, Michelle Rogers and Susan Harvey. Dr. William Karesh (Wildlife Conservation Society) and Dr. Colin Gillin (Centre for Conservation Medicine) provided onsite assistance and international exposure for the project. Dr. Ralph Burt (Agriculture & Agri-Food Canada) conducted some of the on-site testing at the isolation facility. Dr. Stacy Tessaro conducts laboratory tests for Brucella at ADRI, Lethbridge, AB, and has provided invaluable advice and assistance. Dr. Gary Woberser and Dr. Trent Bollinger conducted pathological evaluation of samples from all project mortalities. The Department of Resources, Wildlife and Economic Development, Government of the Northwest Territories provides base funding for this project. The Deninu Kue' First Nation provides in-kind administrative support. The Department of Health and Social Services has assisted with wages for summer students through the Community Animation Program. Funds for planning were provided by the Canadian Wildlife Federation and the Government of Canada through the Arctic Environmental Strategy.

References

Bell, I. 1999. Strict testing on wild elk urged after TB confirmed. The Western Producer. December 16, 1999.

Berguson, D. 1999. Bison monitoring program total count - 1999. Wood Buffalo National Park, Fort Smith, NT., Unpublished Report. 14 pp.

Bison Disease Task Force. 1988. Evaluation of brucellosis and tuberculosis in bison in northern Canada. Bison Disease Steering Committee, Edmonton, AB., Unpublished Report. 252 pp.

Calef, G.W. 1976. Status of bison in the NWT. Northwest Territories Fish and Wildlife Service, Yellowknife, unpub. report. 68 pp + Appendices.

Calef, G.W., and J. Van Camp. 1987. Seasonal distribution, group size and structure, and movements of bison herds. In Bison ecology in relation to agricultural development in the Slave River Lowlands, NWT. eds. H.W. Reynolds and A.W.L Hawley. pp. 15-20. Canadian Wildlife Service Occasional Paper 63. Ottawa, ON.

Carbyn, L.N., S.M. Oosenbrug, and D.W. Anions. 1993. Wolves, bison and the dynamics related to the Peace-Athabasca Delta in Canada's Wood Buffalo National Park. Canadian Circumpolar Research Series No. 4. 270 pp.

Chelack, B.J., P.S. Morley, and D.M. Haines. 1993. Evaluation of methods for dehydration of bovine colostrum for total replacement of normal colostrum in calves. Can. Vet. J. 34: 407-412.

Chisholm, J., L. Comin, and T. Unka. 1998. Concensus-based research to assist with bison management in Wood Buffalo National Park. In: International Symposium on Bison Ecology and Management in North America. eds. L. Irby and J. Knight, pp. 199- 204. Montana State University, Bozeman, Montana.

Chowns, T., C. Gates, and F. Lepine. 1998. Large scale free burning to improve wood bison habitat in northern Canada. In: International Symposium on Bison Ecology and Management in North America. eds. L. Irby and J. Knight, pp. 221-228. Montana State University, Bozeman, Montana.

Davis, D.S., J.W. Templeton, T.A. Ficht, J.D. Williams, J.D. Kopec, and L.G. Adams. 1990. Brucella abortus in captive bison. I. Serology, bacteriology, pathogenesis, and transmission to cattle. J. Wildl. Dis. 26:360-371.

Environmental Assessment Panel. 1990. Northern diseased bison report of the Environmental Assessment Panel. Environmental Assessment Review Office, Report 35. Hull, Quebec. 47 pp.

Fuller, W.A. 1950. Aerial census of bison in Wood Buffalo National Park and vicinity. J. Wildl. Manage. 12: 445-451.

Fuller, W.A. 1966. The biology and management of bison of Wood Buffalo National Park. Wildl. Manage. Bull. Serv. 1(11): 20 pp.

Gates, C.C. 1993. Biopolitics and pathobiology: diseased bison in northern Canada. In: Proceedings of 1st North American Public Bison Herds Symposium. ed. R.E. Walker. pp. 126-135. Lacrosse, WI.

Gates, C.C., T. Chowns, and H. Reynolds. 1992. Wood buffalo at the crossroads. In Alberta: Studies in the Arts and Sciences, Vol. 3(1), Special Issue on the Buffalo. eds. J. Foster, D. Harrison, and I.S. MacLaren. pp. 139-165. University of Alberta Press, Edmonton, AB.

Gates, C.C., B.T. Elkin, and L.N. Carbyn. 1997. The diseased bison issue in northern Canada. In Brucellosis, bison, elk, and cattle in the Greater Yellowstone Area: Defining the problem, exploring solutions. eds. E.T. Thorne, M.S. Boyce, P. Nicolleti, and T.J. Kreeger, pp. 120-132. Wyo. Game and Fish Dept., Cheyenne, WY.

Gates, C.C., B.T. Elkin, and D.C. Beaulieu. 1998. Initial results of an attempt to eradicate bovine tuberculosis and brucellosis from a wood bison herd in northern Canada. In: International Symposium on Bison Ecology and Management in North America. eds. L. Irby and J. Knight, pp. 221-228. Montana State University, Bozeman, MO..

Greater Yellowstone Interagency Brucellosis Committee. 2000. Approved Bison Quarantine Facilities http://www.nps.gov/gyibc/quarant.rtf

Hearne, S. 1795. A journey from Prince of Wales Fort in Hudson's Bay to the northern ocean. Reissued 1971. M.G Hurtig Ltd., Edmonton, Canada. 458 pp.

Huff, D.E and J. Chisholm. 1999. Managing diseased bison in the U.S and the Canadian National Parks. International Symposium on Society & Resource Management. Brisbane, Australia July 6-10, 1999.

Joly, D.O. and F. Messier. 2000. Limiting effects of bovine brucellosis and tuberculosis on wood bison within Wood Buffalo National Park (2000 Annual Report). University of Saskatchewan Unpublished Report to Heritage Canada. Saskatoon, SK. 52 pp.

MacEwan, G. 1995. Buffalo - sacred and sacrificed. Alberta Sport, Recreation, Parks and Wildlife Foundation, Edmonton. AB. 208 pp.

McCormack, P.A. 1992. The political economy of bison management in Wood Buffalo National Park. Arctic. 45: 367-380.

Messier, F and C. Blyth. 1996. Bison-ecosystem interactions in the greater Wood Buffalo National Park: conceptual models and research priorities. Unpublished report to Canadian Heritage, Wood Buffalo National Park, P.O. Box 750, Fort Smith NWT Canada, X0E 0P0, 32 Pp.

Meyer, M.E., and M. Meagher. 1995. Brucellosis in free-ranging bison (Bison bison) in Yellowstone, Grand Teton, and Wood Buffalo National Parks: a review. J. Wildl. Dis. 31: 579-598.

Millette, F.J and A.N. Sturko. 1977. A proposal to review and revise the Anthrax Control Program in Wood Buffalo National Park. Unpublished report, Parks Canada, Fort Smith, NT.

Northern Buffalo Management Board. 1992. Northern Buffalo Management Program Report. Unpublished report submitted to the Government of Canada. Fort Smith, NT. 131 pp.

Ogilvie, S.C. 1979. The park buffalo. Calgary-Banff Chapter, National and Provincial Parks Association of Canada. Sub. P. O. 91, The University of Calgary, Calgary, AB.

Peterson, M.H. 1991. Wildlife parasitism, science, and management policy. J. Wildl. Manage. 55: 782-789.

Plommet, M., R. Fensterbank, G. Renoux, J. Gestin, and A. Philippon. 1973. Experimental bovine brucellosis. XII. Persistance to adult age of congenital infection in the heifer. Ann. Rech. Vet., 4:419.

Preble, E.A. 1908. A biological investigation of the Athabasca-Mackenzie region. U.S. Dept. Agr. N. Am. Fauna. No. 27: 574 pp.

Rankin, J.E. 1965. Brucella abortus in bulls: a study of twelve naturally infected cases. Vet. Rec. 77: 132-135.

Reynolds, H.W and A.W.L Hawley. 1987. Bison ecology in relation to agricultural development in the Slave River Lowlands, NWT. Canadian Wildlife Service Occasional Paper 63. 74 pp.

Rippen, B. 1971. Aerial buffalo survey, Fort Smith, N.W.T., N.W.T. Game Dept. Rep. 13 pp

Schmitt, S.M., S.D. Fitzgerald, T.M. Cooley, C.S. Bruning-Fann, L. Sullivan, D. Berry, T. Carlson, R.B. Minnis, J.B. Payer, and J. Sikarskie. 1997. Bovine Tuberculosis in free-ranging white-tailed deer from Michigan. J. Wildl. Dis. 33:749-758.

Soper, D. 1941. History, range and home of the northern bison. Ecol. Monogr. 2: 347-412.

Sutherland, S.S., and J. Searson. 1990. The immune response to Brucella abortus: the humoral response. In: Animal Brucellosis. Eds. K. Nielson and J.R. Duncan. CRC Press, Bocan Raton, Florida. Pp. 65-81.

Tessaro, S.V. 1988. A descriptive and epizootiologic study of brucellosis and tuberculosis in bison in northern Canada. PhD Thesis, University of Saskatchewan, Saskatoon, SK. 320 pp.

Tessaro, S.V. 1989. Synopsis and literature: zoonotic aspects of Brucella abortus and Mycobacterium bovis with special consideration of the reservoir of brucellosis and tuberculosis in bison in and around Wood Buffalo National Park. Appendix III. In Agriculture Canada Submission to the Northern Diseased Bison Environmental Assessment Panel, November 17, 1989. 96 pp.

Van Camp. J. 1987. Predation on bison. In Bison ecology in relation to agricultural development in the Slave River Lowlands, NWT. eds. H.W. Reynolds and A.W.L Hawley. pp. 25-33. Canadian Wildlife Service Occasional Paper 63. Ottawa, ON.

Van Camp, J., and G.W. Calef. 1987. Population dynamics of bison. In Bison ecology in relation to agricultural development in the Slave River Lowlands, NWT. eds. H.W. Reynolds and A.W.L Hawley. pp. 21-24. Canadian Wildlife Service Occasional Paper 63. Ottawa, ON.

Williams, E.S., S.L. Cain, and D.S. Davis. 1997. Brucellosis: the disease in bison. In Brucellosis, bison, elk, and cattle in the Greater Yellowstone Area: Defining the problem, exploring solutions. eds. E.T. Thorne, M.S. Boyce, P. Nicolleti, and T.J. Kreeger, pp. 1-19. Wyo. Game and Fish Dept., Cheyenne, WY.

Williams, E.S., E.T. Thorne, S.L. Anderson, and J.D. Herriges. 1993. Brucellosis in free-ranging bison (Bison bison) from Teton Country, Wyoming. J. Wildl. Dis. 29:118-122.

Wilson, G. and C. Strobeck. 1999. Genetic variation within and relatedness among wood and plains bison populations. Genome 42: 483-496.

Young, E.J. and P. Nicoletti. 1997. Brucellosis in humans. In Brucellosis, bison, elk, and cattle in the Greater Yellowstone Area: Defining the problem, exploring solutions. eds. E.T. Thorne, M.S. Boyce, P. Nicolleti, and T.J. Kreeger, pp. 147-153. Wyo. Game and Fish Dept., Cheyenne, WY