Mountain goats of Montana
Mountain Goats of Northwest Montana: An Historical Perspective
by Jessy Coltrane, PhD, Kalispell Area Wildlife Biologist
Montana Fish, Wildlife & Parks
Background. — Mountain goats (Oreamos americanus) historically occupied most available montane cliff habitat throughout northwest Montana (Fish Wildlife, & Parks administrative Region 1); however, since the 1950s, native mountain goat numbers have experienced a dramatic decline. Thus, once occupied habitat is now devoid of goats, and current mountain goat range is significantly reduced from its historic expanse.
In the 1940s and 1950s, mountain goats were considered an abundant and not easily depleted resource in northwest Montana. Population estimates for mountain goats in the region described 350 mountain goats in the Swan Mountains, 20 in the North Fork of the Flathead, 315 in the Clark’s Fork, 900 in Glacier Park, 100 near Coram, 450 from Spotted Bear to Schaffer Meadows, and 250 in Big Prairie (Montana Department of Fish and Game 1958). Native herds in the South Fork of the Flathead River and the Swan Mountains were used as source populations to establish new goat herds in mountain ranges throughout Montana and Colorado (Picton and Lonner 2008). In addition to capture removals, wildlife managers allowed for unlimited harvest of mountain goats. At the time, little was known about the ecology of mountain goats, and they were managed similarly to other ungulates, such as bighorn sheep (Ovis canadensis) and white-tailed deer. Local biologists mistakenly believed that increased harvest pressure would increase the productivity of the herd (Montana Department of Fish and Game 1958).
Compounded with the lack of understanding of goat biology, biologists thought the remoteness of mountain goat habitat would impede access, and therefore harvest would never significantly impact the population; however, by the 1960s, timber harvest and associated logging roads pioneered routes into the backcountry, opening the way for hunters. Mountain goats, susceptible to over-harvest and disturbance, began to decline in numbers and entire herds disappeared. By 1960, biologists observed a dramatic decline in goat numbers in certain areas due to increased accessibility, and the first restrictions were placed on goat harvests. By 1972, all hunting districts in the region were being managed by a limited permit system. Unfortunately, it was too late for some goat herds.
Within 30 years, native goat herds had gone from seemingly unlimited resources to depleted and declining. Concern for the species generated studies to better understand their biology and population dynamics. By the early 1980s, research on mountain goats revealed insights into their natural history that distinguishes them from other northern ungulates. Biologists found that female mountain goats exhibit late primiparity (with the majority at 4 to 5 years) and recruitment is extremely low (Adam and Baily 1982, Swenson 1985, Smith 1986, Festa-Bianchet et al. 1994, Cote and Festa-Bianchet 2001a). Productivity for adult females typically increases from 6 to 9 years of age, and senescence begins around 10 years (Cote and Festa-Bianchet 2001a;c). In addition, there is evidence that females produce more male young as they age (Cote and Festa-Bianchet 2001b). Unlike other ungulates, annual production varies dramatically, as well as kid survival (Festa-Bianchet et al. 1994). While yearling survival appears high, mortality of 2- and 3-year-old goats is higher than for other ungulate species, making population recruitment low (Festa-Bianchet et al. 1994). Furthermore, female mountain goats exhibit high site fidelity, which limits dispersal into open habitat, making natural reestablishment of herds difficult (Festa-Bianchet and Cote 2008). These unique biological and social characteristics make them susceptible to over-harvest.
Current goat hunting districts were established in 1986 (Figure 1), and wildlife biologists have been reducing the number of licenses available ever since. Despite dramatically reduced harvest, mountain goat populations in Region 1 have not rebounded to historic levels, and most populations are described by the local management biologists as declining, with a few potentially stable populations. Currently, wildlife biologists in the region are faced with uncertainty concerning the future of native herds and a need for additional data to better ensure their persistence.
Population Monitoring and Trends. — Comparisons of historic survey data to data collected post-1980 indicate a 3- to 4-fold decline in goat numbers throughout northwest Montana; however, evaluation of goat status in more modern times has proved difficult. Due to the sporadic nature of the quality and timing of goat surveys after 1980, it is not possible to complete any statistically valid trend analysis for most hunting districts, except for HDs 100 and 101. Analyses of these survey data indicated declining population trends in both hunting districts. While statistically valid trend analyses are not possible for the remaining hunting districts in Region 1, none of the data indicated growing population trends. At best, it appears that a few hunting districts in the region may have obtained stable number of goats since allowable harvest was severely restricted beginning in the mid-1980s (Table 1).
Harvest Trends. — Prior to 1960, harvest reporting was not consistent, and therefore harvest data are difficult to interpret. Regardless, regional harvest of mountain goats has declined dramatically since the reported high harvest of 295 goats in 1958 to 16 goats in 2016 (Figure 2). In 1963, hunter numbers reached a high of 817 and then steadily declined to 297 hunters in 1970. Presumably, this decline in hunter participation was in part a response to declining goat availability, as success rates dropped from an average of 32% (1960-1963) to 26% (1964-1970), as well. Since 1972, hunter success rate has been a function of available licenses. Since 1984, when permits were reduced to 78, success rate has consistently exceeded 50% (50 – 96%). With few licenses currently available, success rate is not a reliable metric to evaluate goat population status, beyond ascertaining that some goats remain.
Adult survival, particularly survival of older-aged females, and not recruitment, appears to drive population changes in mountain goats (Cote and Festa-Bianchet 2001a, Hamel et al. 2006). Therefore, harvesting adult females can have a profound impact on mountain goat populations. Historically, hunters harvested male and female mountain goats relatively indiscriminately. The relatively high number of females in the harvest might be attributed to the lack of understanding of goat biology on part of the managers and resulting lack of education imparted to hunters. After 1980, biological understanding of mountain goats improved, as did educational efforts to curtail female harvest; however, 10-year averages of percent females in harvest did not drop significantly until 2011 – 2016 (23 ± 11 %), but the number of adult females (≥4 years old) has remained high (38% in 2016). The continued harvest of adult females may reflect low overall population numbers. As populations decline, nanny groups are more easily located due to the relatively larger group size and therefore may be more susceptible to harvest than males.
Sustainable Harvest Rates. — Mountain goats are highly susceptible to over-harvest (Smith 1986, Festa-Bianchet et al. 1994, Côté et al. 2001), as hunting appears almost completely additive to natural mortality in native populations (Adam and Baily 1982, Swenson 1985, Smith 1986, Côté and Festa-Bianchet 2001a). While hunting can be sustainable when managed conservatively, over-harvest has been associated with declines of mountain goat populations across their range (Gonzalez-Voyer et al. 2003, Hamel et al. 2006, Festa-Bianchet and Côté 2008, Rice and Gay 2010). While most biologists recognize the need for conservative management of native mountain goat populations (Smith and DeCesare 2017), determining sustainable harvest rates is challenging. Variability in vital rates and population size influence sustainable rates of harvest (Rice and Gay 2010); however, these data seldom exist for individual populations. In Alberta, Hamel et al (2006) found that native mountain goat populations (> 100 individuals) could tolerate harvest rates of about 1%, and harvest rates greater than 3% were considered not sustainable (Gonzalez-Voyer et al. 2003, Festa-Bianchet and Cote 2008). Rice and Gay (2010) determined that a rate of 4% was sustainable for populations ≥ 100, but indicated that this rate may also cause periodic declines. In addition to harvest rate, size of native populations should be considered carefully when managing mountain goats. Typically, populations with ≤ 25 individuals will have a negative growth rate, even in the absence of hunting, and will face extinction in 40 years.
Determining sustainable rates of harvest for mountain goat populations in Region 1 is wrought with difficulty due to lack of pertinent data, including current or complete survey data for many hunting districts, vital rate data for specific populations, and delineation of functional populations. The number of licenses available in each district is considered the “allowable harvest.” Based on the mid-point of estimated number of goats and the allowable harvest for each hunting district in 2016, harvest rates for all but one district (HD 142) could range from 3 – 12 %. Furthermore, no hunting district was estimated to have goat numbers reaching 100, except for possibly HD 100. If we consider hunting districts within the Bob Marshall Complex (HDs 132, 133, 140, 141, 142, 150 and 151) as a single population, the estimated population would be 359 mountain goats. Current allowable harvest would be approximately 4%. Based on these limited data, it is probable that the current allowable harvest for mountain goats is not sustainable.
Nonhunting Anthropogenic Impacts. — In addition to hunting-related mortality, human activity in goat habitat can impact mountain goat populations by altering habitat use and/or behavior (Chadwick 1974, Foster and Rahs 1983, Cote et al. 2013, St-Louis et al. 2013, Richard and Cote 2016, White and Gregovich 2017). Logging, in particular, has played a role in altering the landscape of northwest Montana since the 1800s. Logging activities and associated road construction in the 1960s and 1970s not only displaced mountain goats, but opened the high country to human access, resulting in increased harvest and poaching (Chadwick 1974).
Recreational activities can also have negative effects on mountain goats, especially during winter and early summer, critical periods when disturbance can result in cumulative negative impacts on survival. In winter, mountain goats are physiologically stressed due to high energetic costs of thermoregulation coupled with low quality and limited nutritional resources. Winter motorized activity, such as helicopter-assisted skiing and snowmobiling, can cause stress responses in goats and displace goats from wintering areas (Hurley 2004). During kidding and post-kidding periods, adult female mountain goats have heightened sensitivity to disturbances (Penner 1988). Compared to other ungulates, mountain goats have a low recruitment rate (Bailey 1991, Festa-Bianchet et al. 1994), and reproductive success and survivorship of goat populations are closely tied to the health of mountain goat nursery groups.
The demand for motorized recreational activities is increasing in and around mountain goat habitat on National Forest Lands (USDA Forest Service 2016). The Forest Service has created alternatives for the Flathead National Forest that do not allow for a net increase in winter motorized travel in mountain goat habitat; however, over-snow motorized travel is allowed in some historic mountain goat habitat, which may continue displacement and/or impede recolonization in these areas.
Conclusions and Management Implications
The biggest management challenge facing mountain goats in Region 1 is the lack of data. Comprehensive and current survey data are needed for most hunting districts, as well as vital rate data for native populations. Determining viable populations of goats within the region is paramount to assess sustainable harvest rates. In lieu of these data, goats should be managed conservatively, including reducing harvest quotas and potentially eliminating licenses in some hunting districts. Based on the available data, we have reduced harvest quotas to one either sex mountain goat in all hunting districts, except HD 101 (reduced to 2) for the 2017/2018 regulatory year. During summer 2017, aerial surveys will be prioritized for hunting districts lacking current or complete survey information.
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