16.6 Status of woodland caribou in a changing landscape

Last Updated: 
November 13, 2015

This indicator tracks landscape changes caused by human activities, one of the main known threats to woodland caribou (Rangifer tarandus caribou) across its range in Canada. This indicator also tracks the status of woodland caribou dwelling in the NWT in the Taiga Plains ecozone (also called boreal caribou) and in the Cordillera ecozone (also called northern mountain caribou).

Boreal caribou
Boreal caribou in the winter.

Landscape change is measured as ‘fragmentation density' in each of the NWT’s forested ecoregions. These ecoregions are subdivisons of the NWT’s larger ecozones. Ecoregions have distinctive ecological factors including climate, physiography, vegetation, soil, water and fauna. Each ecoregion can be considered unique and, if fragmented, cannot be replaced elsewhere. Fragmentation density levels are measured as total buffered area of human features divided by total area in each ecoregion, in km2 per km2. Human features included are communities, mines, oil-gas wells, pipelines (all below ground), seismic lines, roads, power stations, power lines and the Canol Trail.

Seismic lines and fire scars in the Taiga Plains
Seismic lines and fire scars in the Taiga Plains – see VEGETATION for details on natural disturbances like fire.

Information on caribou for this indicator is obtained from woodland caribou surveys conducted by ENR biologists1. Status assessment information is obtained from the 2002 COSEWIC status report on woodland caribou2, undated COSEWIC report on Northern Mountain Caribou3 and the Species at Risk Committee (SARC) report on Boreal Caribou4.

Habitats for woodland caribou in the NWT are naturally fragmented. For example, forests are part of a natural mosaic of wetlands, peatlands and areas burned by wild land fires that is always changing. Caribou have adapted to this level of natural fragmentation. The fragmentation densities calculated in this indicator result from human activities and should be considered in addition to the natural fragmentation of the landscape.

Data for the location of human features are from the National Energy Board, the National Road Network, Aboriginal Affairs and Northern Development Canada, the NWT Geoscience Office and the NWT Centre for Geomatics, Government of the Northwest Territories. Buffers are from expert opinion and peer-reviewed papers (see details in the Technical Note below). Source of ecoregion information is NWT Ecological Classification.

This indicator incorporates and replaces “8.2 Fragmentation Density” indicator published in 2010.

NWT Focus

Aboriginal people have been harvesting woodland caribou for generations. Woodland caribou are a different sub-species than barren-ground caribou (Rangifer tarandus groendlandicus). They are larger, taller, darker brown, and have thicker, broader antlers than barren-ground caribou. Woodland caribou are found throughout the Cordillera and Taiga Plains ecozones of the NWT. Woodland caribou require habitat that will provide enough food and protection from predators to keep local populations healthy.

Monitoring the status of woodland caribou in the NWT is important to help track the effects of landscape changes due to human activities on a species at risk particularly sensitive to these changes. Land use activities impact the natural environment in many ways. Some activities remove vegetation and add to the fragmentation of the natural landscape for many generations. Certain large herbivores, such as woodland caribou, are known to avoid these areas. As more infrastructure and renewable and non-renewable resources are developed in the NWT, management agencies are monitoring cumulative impacts of fragmentation on the NWT’s biodiversity.

Current view: status and trend

Landscape Changes

Fragmentation densities are higher in some areas in the NWT than others. These high-density areas are grouped in four sectors as noted on the map below. For example, a level of 0.6 km2/km2 means that in that ecoregion, an animal such as a woodland caribou has a 60% chance of being within a buffer zone near a human feature.

Sector a:  Mackenzie Delta ecoregion: human features result in 0.34 km2/km2 fragmentation in the Mackenzie Delta mostly from seismic lines, winter roads, and gas wells.

Sector b:  A group of ecoregions in the Sahtu show fragmentation due to seismic lines and wells: Colville Hills (0.33 km2/km2), Arctic Red Plains (0.21 km2/km2) and North Mackenzie Plains (0.27 km2/km2) ecoregions.

Sector c: Features such as seismic lines, wells sites, and roads result in 0.40 km2/km2 and 0.35 km2/km2 fragmentation density in the Liard Upland and Liard Plains, respectively. Trout Upland shows 0.18 km2/km2 fragmentation density.

Sector d: On the Cameron Plateau and Upland ecoregions seismic lines, well sites and roads result in 0.66 km2/km2 and 0.44 km2/km2 fragmentation density respectively, in addition to fires that are part of natural disturbance regime.

As seen in this photograph taken in summer 2005, efforts are underway to reduce the effects of 3D seismic by reducing the line of sight of predators by building in slight curves in each line.

An unknown number of additional seismic lines have been created in the NWT since 2000. As well, an unknown proportion of the old seismic lines included in the data set used for this indicator may have re-grown and may not be as visible on the landscape. By comparing the NEB data set of pre-1999 lines with maps of visible seismic lines obtained from satellite images for the Dehcho, it was found that the NEB data are incomplete. As a result, the density estimates presented here should be considered as minimum baseline numbers.

Status of woodland caribou

Boreal caribou are declining throughout much of their range in North America. Boreal caribou are listed as threatened and northern mountain caribou were listed as a species of special concern in Canada under the federal Species at Risk Act2. The status of northern mountain caribou in Canada was re-assessed in 20143. Threats to woodland caribou can include linear corridors such trails, roads and seismic lines, increased predation due to access along corridors, changes in disease and, in some areas, over-harvesting.

Local knowledge suggests that “where changes are recorded (in distribution), they are variable and local: some specific areas in the NWT used to have boreal caribou do not anymore, or do not have many. Their distribution may have cycles with decades between the highs and lows.”4

Survey Unit

Survey Year

Numbers in Survey Unit(s)

Population Trends

Northern Mountain Caribou (Each herd is shared with Yukon)

Redstone Herd




Nahanni Complex - Coal River herd




Nahanni Complex - La Biche herd 1


About 400


Nahanni Complex - South Nahanni herd 2




Bonnet Plume Herds1


About 4,200


Boreal Caribou

Gwich’in - Sahtu9




North Slave     ?

South Slave - Hay River Lowlands study area7



South Slave-Cameron Hills study area7











Stable or Declining





Northern mountain caribou estimates are summarized from the 2014 COSEWIC report3Boreal caribou information summarized from the 2012 SARC report4.

1 Low confidence in estimated numbers.

2 Recent mark/re-sight survey leading to high confidence in numbers.

Looking forward

This indicator will continue to track changes in fragmentation densities, providing a “footprint” of human features using the information provided by the National Energy Board and other regulatory agencies. The effects of increasing seismic line densities on woodland caribou population trends are being studied and will be reported in this indicator in the future.

Management and recovery actions are being implemented in a coordinated fashion in Canada. Detail of the management of northern mountain caribou in the NWT can be found in the National Management Plan5. Details on management and recovery actions of boreal caribou in the NWT are described in the National Recovery Strategy6

Looking around

The NWT is less fragmented and less developed than many parts of southern Canada, although an increase in development is expected in the future. Currently, woodland caribou populations in the NWT are among the more sustainable in Canada, though continued monitoring is needed to help make sure these populations remain healthy5,6.

Find out more

Other focal points

The density of seismic lines presented here only reflects seismic lines created up to 2000, and therefore the density figures are already dated. Numerous 2D and 3D seismic line programs were carried out between 2001 and 2005 in sectors a, b, c, and d. Available details for these recent seismic programs can be found in the Human Activities focal point.

Technical Notes

Reference range map of Northern Mountain caribou herds in NWT, Yukon, and northern BC.

NWT Fragmentation Map - GIS procedures

Purpose was to visually depict the fragmentation density in each NWT Level IV ecogreion with an intuitive color scheme. GIS processes and map creation were carried out using ESRI ArcGIS 9.3 software with ArcMap and ArcInfo licenses. To allow accurate area calculations, we used Albers Conical Equal Area projection with these NWT-specific parameters: 0 - False Easting, 0 - False Northing, -119 - Central Meridian, 62 - 1st Standard Parallel, 70 - 2nd Standard Parallel, 0 - Latitude of origin, NAD83 - Datum. All data layers used in area calculations were re-projected to the above projection. The map was created using shapefiles of the Level IV ecoregions in the Taiga Plains, Taiga Shield, and Boreal and Taiga Cordillera Level II ecoregions (NWT Ecosystem Classification Group 2007, 2008, 2009, available here.

A single “buffered features” layer (shapefile) was created using the feature data listed in the table below. Each feature was buffered at the defined buffer radius, followed by an amalgamation process. During amalgamation, overlapping buffer areas were calculated only once. We used ArcGIS geoprocessing functions: buffer, dissolve, merge and union. All buffered and dissolved layers were unioned into one master “buffered features” data layer, which required a dissolve function to create a single multipart polygon.

Fragmentation density for each Level IV ecoregion was calculated using these steps:

1.      In each Level IV ecoregion shapefile, total area coverage, in km2, was calculated using the geometry command.

2.      In each Level IV ecoregion shapefile, total area of “buffered features”, in m2 (default map unit), was calculated using Hawths Analysis Tools version 3.26 in ArcMap and the Polygon in Polygon Analysis tool.


Map of all features. Seismic line features in the Beaufort Sea and on Arctic ecozones were not used in the analysis, but are shown here for completeness. Map created by NWT Centre for Geomatics, 2010. This map is not a legal description and is provided without prejudice.

3.     In each Level IV ecoregion, fragmentation density (F) was calculated using ArcGIS field calculator as:

Fragmentation density is thus the total “buffered features” area in a Level IV ecoregion divided by the total area of that Level IV ecoregion.  Measurement units are km2.

A map illustrating the distribution of all the fragmentation features (data) used to calculate the “buffered features” layer is shown.  Fragmentation density was not calculated for non-forested ecozones, as Level IV ecoregion layers were not available as of January 2010.

Sources, year of data availability, and references used to determine the buffer radius for each feature type are tabled below.

Feature Type


Buffer Radius


Year of Data

City of Yellowknife (Pop >5,000) iv

10,000 a


Mine - active iii, Medium Towns (Pop <5,000) iv


3,000 b


All weather roads ii

2,000 c



Mines – under maintenance iii, Oil-gas wells – active i


Winter roads 31, Power stations iv,


Small Towns (Pop <1,000) iv , Lodges iv

1,000 d








Seismic lines i,

Mines – non active i,

Power line iv,

Canol Trail iv

500 e


Before 2000




Pipeline (below ground) v

300 f

About 2000

Oil-gas wells – non-active e

250 g


Feature data are from i National Energy Board; ii National Road Network; iii Indian and Northern Affairs Canada and NWT Geoscience Office; iv NWT Centre for Geomatics, v Government of the Northwest Territories. Data for seismic lines was obtained from the National Energy Board (NEB) in October 2009. However, the newest data in the file was released in 2005 and is current to 2000 only. Seismic lines in this data set were created between 1958 and 2000.

Buffer radius 10,000m a is from approximate actual extent of Yellowknife’s city limits; radius 3,000m b.is from actual extent10, with additional buffer based on space use analysis by caribou in Labrador11; radius 2000mcis based on functional response of boreal caribou near the Dempster Highway (Nagy, 201112), is larger than estimated for caribou and small roads and seismic lines in northern Alberta (250m)13,14 but smaller than estimated for caribou outfitter camps and roads in Scandinavia (5,000m)15; radius 1000 d is based on actual extent plus a buffer similar to estimates for well sites14, and winter roads10; radius 500m e is based on functional response of boreal caribou in northern NWT and findings of critical habitat needs for boreal caribou across Canada (Nagy 201112, Environment Canada. 201216), and is slightly larger than estimates of predation effects in northern Alberta (316m)13,17; radius 300m f is from actual extent plus the radius of seismic limes; radius 250m g is from northern Alberta14.


Found an error or have a question? Contact the team at NWTSOER@gov.nt.ca.


Ref 1 - ENR. 2011. NWT Woodland Caribou (Rangifer tarandus caribou) Boreal population / Northern Mountain population. ENR- Wildlife Webpage. Government of the Northwest Territories.

Ref 2 - Thomas D. C., D.R.Gray 2002. Update COSEWIC status report on the woodland caribou Rangifer tarandus caribou in Canada, Committee on the Status of Endangered Wildlife in Canada, Ottawa.

Ref 3 - COSEWIC. 2014. Update COSEWIC report on the Caribou (Rangifer tarandus) in the Northern Mountain Central Mountain and Southern Mountain designatable units. Environment Canada. 109 pp.   

Ref 4 - SARC. 2012. Status report of Woodland Caribou (Boreal Population) in the NWT. ENR. 145 pp. Available at www.nwtspeciesatrisk.ca

Ref 5 - Environment Canada. 2012 Management Plan for the Northern Mountain Population of Woodland Caribou (Rangifer tarandus caribou) in Canada. Species at Risk Act Management Plan Series. Environment Canada, Ottawa. vii + 79 pp. Available at http://publications.gc.ca/collections/collection_2012/ec/En3-5-25-2012-eng.pdf

Ref 6 - Environment Canada. 2012. Recovery Strategy for the Woodland Caribou (Rangifer tarandus caribou), Boreal population, in Canada. Species at Risk Act Recovery Strategy Series. Environment Canada, Ottawa. xi + 138pp. Available at https://ca.fsc.org/download.canadian-federal-recovery-strategy.173.pdf

Ref 7 - Kelly A., Cox K. 2011. Boreal Caribou Progress Report: Hay River Lowlands and Cameron Hills Study Areas 1 April 2008 – 31 March 2010 , Government of Northwest Territories, Environment and Natural Resources, Fort Smith, NT.

Ref 8 - Larter N.C., Allaire D. 2011. Dehcho Boreal Caribou Study Progress Report, April 2011, Government of Northwest Territories, Environment and Natural Resources, Fort Simpson, NT.

Ref 9 - Nagy, J. A. S. 2011. Use of space by caribou in northern Canada. Ph.D. dissertation, University of Alberta, Edmonton, Alberta, Canada. 184 pp.

Ref 10 - Johnson C. J. et al. 2005. Cumulative effects of human developments on Arctic wildlife, Wildlife Monographs1-36

Ref 11 - Mahoney S. P. S. J. A.2002. Hydroelectric development and the disruption of migration in caribou. Biological Conservation 107:147-153

Ref 12 - Nagy J. A.2011. Use of space by caribou in northern Canada, Ph.D. Thesis, University of Alberta, Edmonton, AB.

Ref 13 - Dyer, S.J., J.P. O'Neill, S.M Wasel, and S. Boutin. 2002. Quantifying barrier effects of roads and seismic lines on movements of female woodland caribou in northeastern Alberta. Can. J. Zool. 80:839-845.

Ref 14 - Dyer, S. et al. 2001. Avoidance of Industrial Development by Woodland Caribou. J. Wild. Mana. 65: 531-542.

Ref 15 - Nellemann et al. 2001. Winter distribution of wild reindeer in relation to power lines, roads, and resorts. Biological Conservation 101: 351-360.

Ref 16 - Environment Canada. 2012. Recovery Strategy for the Woodland Caribou, Boreal population (Rangifer tarandus caribou) in Canada. Species at Risk Act Recovery Strategy Series, Environment Canada. Ottawa, ON.

Ref 17 - James A.R.C. and A.L. Stuart-Smith. 2000. Distribution of caribou and wolves in relation to linear corridors. Journal of Wildlife Management 64:154-159