Population Dynamics and Harvest Potential of Mountain Goat Herds in Alberta

Abstract

The understanding of population dynamics is a central issue for managing large mammals. Modeling has allowed population ecologists to increase their knowledge about complex systems and better predict population responses to diverse perturbations. Mountain goats (Oreamnos americanus) appear sensitive to harvest, but the relative influence of survival and reproductive rates on their population dynamics are not well understood. Using longitudinal data on age‐ and sex‐specific survival and reproduction from a marked mountain goat population in Alberta, Canada, we built a stage‐class matrix model to predict short‐term numerical changes for 11 other goat populations in Alberta for which the only data available were from annual aerial surveys. Overall, the model provided an acceptable fit to changes in population size for 8 of 12 populations. Temporal trends in population size were underestimated in 2 populations and overestimated in another 2, suggesting that these populations had different vital rates than those of the intensively studied population. Sensitivity analyses revealed that the survival of mature females (aged 5 yr and older) had the greatest elasticity for population growth. Modeled management scenarios indicated that nonselective yearly harvest rates above 1% of goats aged 2 years and older were not sustainable over the short‐term for some populations. The simulations also revealed that small (n = 25) and medium‐size (n = 50) populations, which correspond to most goat populations in Alberta, had high extinction risk (18 to 82% over 40 years), even in the absence of harvest. Our results confirm that mountain goat populations are very sensitive to harvest, indicate that wildlife managers should prevent female harvest, and suggest that although a high demand for goat hunting exists in Alberta, most populations in this province—and probably small populations elsewhere—cannot withstand exploitation.

Low MHC DRB class II diversity in the mountain goat: past bottlenecks and possible role of pathogens and parasites

“…Signs of apparent diseases or ectoparasites were noted during captures. Nearly all individuals within the population are marked (98% of goats aged ‡1 year old since 1993) and observed daily from May to September each year, providing accurate counts of population size (Hamel et al 2006). …”

GPS Bias Correction and Habitat Selection by Mountain Goats

“…In the Washington Cascades, some population estimates suggest declines of as much as 70% over the last 40 years (Washington Department of Fish and Wildlife unpublished data). Population declines and a re-evaluation of harvest potential for this species [3,4] have resulted in a reduction of harvest across Washington and has prompted research into the status of this unique ungulate [5]. Conservation and recovery of mountain goat populations depends upon an understanding of habitat use [6].…”

Responses of mountain goats to heliskiing activity: Movements and resource selection.

“…animals (Poole and Adams 2002, G onzalez-Voyer et al 2003, Hamel et al 2006, M ountain Goat M anagement Team 2010. The decline o f these populations has been m et with considerable concern from wildlife managers and the public because recent w ork indicates that small mountain goat herds (<50 animals) have a high extinction risk (18% -82% over 40 years) even in the absence o f harvest (Hamel et al 2006). Understanding and managing for the factors underlying these population declines is critical for the recovery o f threatened populations and the pro-active conservation o f those that are currently stable.…”

“…In mountain goat populations, where changes in population size are most influenced by reproductive females (Hamel et al 2006), this should be carefully considered.…”

“…In ungulates, it is generally found that female with offspring have a higher perception of predatory risk (Horejsi 1981, Hamel and Cote 2007, Ciuti et al 2008, so it follows that they may be more sensitive to disturbance as well. If this was dem onstrated, it w ould suggest that contracted separation distances that allowed for the frequent disturbance o f sensitive individuals may com prom ise the most demographically important subset o f the mountain goat population (i.e., reproductive females; Hamel et al 2006, Festa-Bianchet andCote 2008).…”