2018 status Kangerlussuaq-Sisimiut caribou West Greenland. Technical Report No. 117

West Greenland (south of 69°N) has six caribou (Rangifer tarandus) regions 
that contain several distinct populations. This report presents new 
information, from a survey carried out in 2018, about the KangerlussuaqSisimiut (KS) population, which inhabits the North region. 
The KS caribou were last surveyed in March 2010. Since then, there have been 
long autumn hunting seasons of unlimited harvest, as well as a winter season. 
A new estimate of abundance was overdue. Helicopter surveys in 2000, 2005 
and 2010 used strip transect counts. In March 2018, helicopter was again used, 
and for the first time Distance Sampling methods and analyses were applied. 
Previous surveys have documented that Greenland caribou are 
extraordinarily camouflaged against typical environmental conditions in 
Greenland, and how this could reduce detection of caribou present within the 
surveyed area. While almost anyone can detect running animals, stationary 
animals can be difficult to detect. To investigate the proportion of non-moving
caribou, the 2018 survey recorded caribou flight responses or lack thereof for 
every group observed. Flight movement was absent in almost 32% of all 
caribou groups observed during the survey. This underlines the importance 
of skilled observers, as well as flying low and slow to make detection of 
caribou easier. The 2018 survey’s Distance Sampling methods and analyses 
corrected for undetected caribou and provided a robust estimate for caribou 
abundance and density (below). It is reasonable to expect that any survey for 
caribou would have some proportion of non-moving caribou present in the 
surveyed area of the line transects. Additional results from two Greenland 
caribou surveys completed in 2019, will confirm whether the observed 
proportion in 2018, almost 1/3 non-moving caribou groups, is atypical or 
typical. If typical, this suggests that a survey dataset including few 
observations of stationary caribou groups would underestimate population 
size correspondingly.
In early March 2018, observed KS caribou were at relatively low elevations, 
mean 361 m. A high proportion of polled KS cows was observed, 46%, which 
is similar to earlier reports for this population. Polled cows are not likely due 
to poor body condition, as is the common assumption for populations 
elsewhere. For KS, polled cows may be the result of a reduced need for the 
dominance conferred by antlers, given their small group sizes, and the xeric 
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climate reducing the need of competing for feeding craters dug down through 
deep snow to obtain forage.
The March 2018 demographics were improved relative to observed in 2005 
and 2010. Specifically, late winter calf (age ≤ 10-months) percentage was ca. 
21.8%, and calf recruitment was ca. 42 calves per 100 cows. However, 26-32% 
of all calves were likely orphans without dams. This suggests that the true late 
winter value for calf percentage was closer to 17% and recruitment ca. 31 
calves per 100 cows. This level of recruitment is higher than the observed in 
2005 and 2010. The March 2018 sex ratio was ca. 51 bulls per 100 cows. The 
March 2018 demographics describe a caribou population that appears capable 
of withstanding current harvests, while the calf recruitment is not high 
enough to suggest the possibility of rapid population growth. Stochastic 
catastrophic events excepted, there appears to be a low risk for future 
population decline, while there is potential for slow growth.
For March 2018, survey coverage was 10.6% of the study area, which is a 
substantial improvement from the 1% coverage of the 2000-2010 strip transect 
count surveys. The North region’s 2018 KS caribou population abundance 
was estimated at ca. 60,469 caribou (95% CI: 51,932–70,410; CV = 0.074; SE = 
4,501), with a density of ca. 2.59 caribou/km2 (95% CI: 2.23–3.02). This 
Distance Sampling estimate was precise (CV = 7.4%). The population estimate 
is ca. 38.5% lower than the estimated number of KS caribou in 2010. Before 
concluding that a large decline has occurred, caution is needed because 
several mitigating factors must be recognized. The 2010 survey had low 
coverage and a high Coefficient of Variance (CV). Thus, it was likely not as 
accurate or precise as the 2018 survey. Also, better GIS mapping in 2018 
resulted in a smaller total area, which means that the 2010 estimate was 
inflated. Furthermore, in 2018 survey methods changed to Distance Sampling. 
This by itself precludes trend projections based on just the current and the 
2010 strip transect count surveys. To predict a somewhat reliable population 
trend, a time series of at least three estimates is needed and these must be 
obtained with comparable methods. Albeit the 2018 Distance Sampling 
estimate of ca. 60,469 caribou suggests decline in KS caribou abundance and 
some decline could be expected, given both the poor calf recruitment of the 
2005-2010 period and over a decade of harvest management aimed at 
reducing KS caribou abundance. Regardless, this report’s good late winter calf 
recruitment for 2018 does not support future decline. Instead, it suggests 
possible stability or slow growth in future. It is also worth mentioning that an 
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alternate Model-based analysis of the 2018 dataset estimated a somewhat 
higher 73,895 caribou (95% CI: 65,983-82,757, CV = 0.037) (Correia 2020). 
Given there are two estimates begs the question, which is the most accurate 
and precise? This is currently being investigated, requires additional results 
from two other West Greenland caribou surveys completed in 2019, and 
conclusions regarding Distance Sampling and Model-based estimates will be 
published in a peer-reviewed journal.
Whether 60,469 (95% CI: 51,932–70,410) or 73,895 (95% CI: 65,983-82,757), the 
2018 KS caribou population size remains large relative to the area available, 
23,303 km2. The KS caribou density from Distance Sampling was 2.6 caribou 
per km2. Given good calf recruitment, population decline is not expected in 
the immediate future. Like all estimates since 2000, the 2018 density exceeds 
the recommended management target of 1.2 caribou per km2. Exceeding the 
target density was assumed to raise risk of overgrazing and lead to 
abundance decline. In Alaska and Canada, when overgrazing played a major 
role, caribou declines took place over 15 to 20 years. Nevertheless, even after 
almost two decades of high densities exceeding the target have passed, there 
is no strong evidence of extensive overgrazing or decline in the KS caribou. 
Since in 2018 recruitment improved to at least 31 calves per 100 cows, despite 
an overall density of 2.6 caribou per km2, it appears that the North region can 
support a higher density than expected. Pending additional results from two 
other West Greenland caribou surveys completed in 2019, the target density 
for caribou management will receive re-evaluation regarding what level is 
compatible with demographics that facilitate sustainable populations and 
harvests in Greenland.