2018 status muskoxen, Maniitsoq & Sisimiut, West Greenland. Technical Report No. 119

This report presents results from the first systematic aerial survey of muskoxen in 
southwest Greenland. The survey involved the North region (66°-68°N), which was 
divided into three sub-areas (Angujaartorfiup, Sisimiut, Sisimiut South). The survey 
occurred early March 2018 and provides the first estimate for muskox abundance in 
two muskox harvest management areas, Maniitsoq (66°-67°N) and Sisimiut (67°-68°N).
The behavior of most muskox groups was unaffected by the helicopter fly-by at 40 m 
altitude. Regardless of group size, 77% of groups simply stood still. Detecting 
stationary groups is clearly essential for accurate population estimates. 
Sisimiut muskoxen were most often observed at elevations of ca. 200 m, which is 
typical for this species as they prefer to forage in lowland elevations even in winter. In 
sharp contrast, Maniitsoq muskoxen used 700-800 m elevations, despite their 
documented year-round preference for lowlands <400 m. Further, at the time of the 
survey, Maniitsoq muskoxen were clumped into two ‘hotspots’ almost inaccessible by 
motor vehicle and relatively far from human habitation. Since 84% of all muskox 
harvest (commercial and recreational), as well as most trophy hunting and qiviut 
(muskox inner wool) production in Greenland are taken from the Maniitsoq muskox
population, these activities may have a role in the disruption of normal lowland 
distribution of the Maniitsoq muskoxen in winter.
From a subset of the Maniitsoq data, the calf (age <1-year) percentage was ascertained 
ca. 18% for Maniitsoq muskoxen. Considering the absence of large predators, the 
current value is considered low. Factors involved may include density-dependent 
issues associated with the Maniitsoq muskoxen now foraging on high elevation 
suboptimal habitat in winter. Since this coincides with late gestation for muskoxen, calf 
production could be negatively affected. Whether current calf percentage is sufficient to 
support population size stability or growth is debatable.
Population size & density estimates
Conventional Distance Sampling (DS) design-based methods and analyses, as well as 
Generalized Additive Models/Density Surface Modelling (GAM/DSM) based analyses 
were applied to the dataset to obtain estimates of muskox population size and density. 
Most muskoxen occurred in the Maniitsoq muskox harvest management area
(surveyed Angujaartorfiup sub-area). Far fewer muskoxen inhabited the Sisimiut 
muskox harvest management area (surveyed Sisimiut sub-area), and zero muskoxen 
were observed in the surveyed Sisimiut South sub-area. Densities from the GAM/DSM 
model-based analysis supported that in early March, muskoxen strongly preferred
9
Southwest facing slopes and specifically for Maniitsoq muskoxen the highest densities
coincided with high elevations. 
For the entire North region, the DS design-based March 2018 muskox population 
abundance was estimated at 21,746 muskoxen (95% CI: 11,061–42,751; CV = 28.5%; SE: 
6,194), with a density of 1.1 muskoxen/km2 (95% CI: 0.559–2.160; CV = 28.5%; SE = 
0.313). Alternately for the entire North region, the GAM/DSM model-based March 
2018 muskox population abundance was estimated 23,256 muskoxen (95% CI: 18,102–
29,877; CV = 11.36%), with mean density of 3.69 muskoxen/km2
(95% CI: 2.87-4.74). 
DS estimates as per specific sub-area:
Maniitsoq muskoxen (Angujaartorfiup sub-area): The DS design-based estimate 
was ca. 18,906 muskoxen (95% CI: 8,726–40,960; CV = 0.315; SE = 5,948), with a 
density of ca. 2.6 muskoxen/km2 (95% CI: 1.223–5.742; CV = 0.315; SE = 0.834). 
Sisimiut muskoxen (Sisimiut sub-area): The DS design-based estimate was ca. 
2,840 muskoxen (95% CI: 662–12,178; CV = 0.568; SE = 1,613), with a density of 
ca. 0.22 muskoxen/km2 (95% CI: 0.052–0.962; CV = 0.568; SE = 0.127).
The population size estimates from the two approaches were similar since the 95%CIs 
overlap. Despite the good survey coverage (10.6%), the high variability within the 
dataset was responsible for substantial uncertainty in the DS estimates and less so in 
the GAM/DSM. Regardless, calculating the CV for probability of detection of 
muskoxen permitted comparison of the two approaches. The DS probability of muskox 
detection had a CV of 5.98%, which was better than the CV of 11.36% for the 
GAM/DSM. Thus, for the 2018 survey for muskoxen, we recommend using the DS 
design-based abundance and density estimates when making management decisions. 
Alone, the 2018 estimate cannot indicate population trend. That requires at least two 
additional aerial survey estimate points using similar methods. Meanwhile, past 
counts, densities, harvests, and calf percentages do not suggest recent population 
growth but possibly a decline prior to the 2018 survey. Regardless, specifically the 2018 
population size estimate for Maniitsoq muskoxen is larger than previous estimates for 
populations anywhere in Greenland. Also, Maniitsoq muskox density is much higher 
than elsewhere in the Arctic. This could increase exposure of individuals to infectious 
pathogens. Given possible density-dependent influences acting at current population 
size, population growth may not be advisable. Whether the 2018 population size and 
density for the Maniitsoq muskox harvest management area are within the current 
herbivore carrying-capacity of the pasture/range remains to be seen.