Technical Thematic Report No. 11. - Woodland caribou, boreal population, trends in Canada

  1. Introduction
  2. Figures and Tables
  3. Threats
  4. Trends in protected caribou habitats
  5. Herd-specific assessments
  6. References

Document Information

Woodland caribou, boreal population, trends in Canada

C. Callaghan,[1] S. Virc[2] and J. Duffe[3]

Canadian Biodiversity: Ecosystem Status and Trends 2010
Technical Thematic Report No. 11
Published by the Canadian Councils of Resource Ministers

Library and Archives Canada Cataloguing in Publication

Woodland caribou, boreal population, trends in Canada.

Issued also in French under title:
Tendances de la population boréale du caribou des bois au Canada.
Electronic monograph in PDF format.
ISBN 978-1-100-18650-4
Cat. no.: En14-43/11-2011E-PDF

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This report should be cited as:
Callaghan, C., Virc, S. and Duffe, J. 2011. Woodland caribou, boreal population, trends in Canada. Canadian Biodiversity: Ecosystem Status and Trends 2010, Technical Thematic Report No. 11. Canadian Councils of Resource Ministers. Ottawa, ON. iv + 36 p .

© Her Majesty the Queen in Right of Canada, 2011
Aussi disponible en français

 

Preface

The Canadian Councils of Resource Ministers developed a Biodiversity Outcomes FrameworkFootnote1 in 2006 to focus conservation and restoration actions under the Canadian Biodiversity Strategy.Footnote2Canadian Biodiversity: Ecosystem Status and Trends 2010Footnote3 was a first report under this framework. It assesses progress towards the framework's goal of "Healthy and Diverse Ecosystems" and the two desired conservation outcomes: i) productive, resilient, diverse ecosystems with the capacity to recover and adapt; and ii) damaged ecosystems restored.

The 22 recurring key findings that are presented in Canadian Biodiversity: Ecosystem Status and Trends 2010 emerged from synthesis and analysis of technical reports prepared as part of this project. Over 500 experts participated in the writing and review of these foundation documents. This report, Woodland caribou, boreal population, trends in Canada, is one of several reports prepared on the status and trends of national cross-cutting themes. It is based largely upon the results from the Scientific Review for the Identification of Critical Habitat for Woodland Caribou (Rangifer tarandus caribou), Boreal Population, in Canada (Environment Canada, 2008).

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Acknowledgements

We thank the authors and supporters of the Scientific Review for the Identification of Critical Habitat for Woodland Caribou (Rangifer tarandus caribou), Boreal Population, in Canada (Environment Canada, 2008) which was made possible thanks to the contributions of the following individuals (Note: a more detailed list of acknowledgements is available in the Scientific Review): Dr. Fiona Schmiegelow, Dr. Stan Boutin, Dr. Carlos Carroll, Dr. Réhaume Courtois, Dr. Vince Crichton, Dr. Marie-Josée Fortin, Dr. Mark Hebblewhite, Mr. Dave Hervieux, Mr.John Nagy, Dr. Tom Nudds, Dr. Richard Pither, Mr. Gerry Racey, Dr. Justina Ray, Dr. Jim Schaefer, Dr. Isabelle Schmelzer, Dr. Dale Seip, Dr. Don Thomas, Mr. Tim Trottier, Mr. Stephen Virc, Ms. Cathy Nielsen, Dr. Carolyn Callaghan, Dr. Ian Thompson, Mr. Jason Duffe, Mr. Jean-François Gobeil, Mr. Ken Harris, Dr. Sophie Czetwertynski, Ms. Deborah Durigon, Ms. Kim Lisgo, Ms. Erin Neave, Ms. Lise Picard, Mr. Mark Richardson, Mr. Robert Vanderkam, Mr. Peter Lee, Dr. Jim Stritholt, Dr. Joerg Tews, Ms. Liv Vors.

We also thank the reviewers of this report.

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Ecological Classification System – Ecozones+

A slightly modified version of the Terrestrial Ecozones of Canada, described in the National Ecological Framework for Canada,Footnote4 provided the ecosystem-based units for all reports related to this project. Modifications from the original framework include: adjustments to terrestrial boundaries to reflect improvements from ground-truthing exercises; the combination of three Arctic ecozones into one; the use of two ecoprovinces – Western Interior Basin and Newfoundland Boreal; the addition of nine marine ecosystem-based units; and, the addition of the Great Lakes as a unit. This modified classification system is referred to as "ecozones+" throughout these reports to avoid confusion with the more familiar "ecozones" of the original framework.Footnote5

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Ecological classification framework for the Ecosystem Status and Trends Report for Canada.

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Long Description for Ecozones+ map of Canada

This map of Canada shows the ecological classification framework for the Ecosystem Status and Trends Report, named “ecozones+”. This map shows the distribution of 15 terrestrial ecozones+ (Atlantic Maritime; Newfoundland Boreal; Taiga Shield; Mixedwood Plains; Boreal Shield; Hudson Plains; Prairies; Boreal Plains; Montane Cordillera; Western Interior Basin; Pacific Maritime; Boreal Cordillera; Taiga Cordillera; Taiga Plains; Arctic), two large lake ecozones+ (Great Lakes; Lake Winnipeg), and nine marine ecozones+ (North Coast and Hecate Strait; West Coast Vancouver Island; Strait of Georgia; Gulf of Maine and Scotian Shelf; Estuary and Gulf of St. Lawrence; Newfoundland and Labrador Shelves; Hudson Bay, James Bay and Fox Basin; Canadian Arctic Archipelago; Beaufort Sea).

Introduction

The woodland caribou (Rangifer tarandus caribou) is a member of the deer family that is distributed throughout the boreal region of Canada (Banfield, 1961). Two genetically distinct varieties, or ecotypes, of woodland caribou have been assessed by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). Forest-dwelling woodland caribou are sedentary (non-migratory), live in relatively small groups, and occupy the boreal forest year-round. Forest tundra woodland caribou (migratory), live in large herds, occupy the boreal forest during winter, and migrate longer distances to the open tundra of the Hudson Bay Lowlands for the calving period. These ecotypes are based on the taxonomy of woodland caribou as proposed by Banfield (1961), the National Ecological Areas adopted by COSEWIC in 1994, and genetic and ecological differences among woodland caribou (COSEWIC, 2002).

The forest-dwelling ecotype of woodland caribou is comprised of five geographically distinct populations, including boreal (Threatened), northern mountain (Special Concern), southern mountain (Threatened), and Atlantic-Gaspésie population (Endangered), and the insular Newfoundland population (Not at Risk). In 2002, COSEWIC assessed the boreal population of forest-dwelling woodland caribou (hereafter referred to as boreal caribou) as Threatened (COSEWIC, 2002) and boreal caribou were added to Schedule 1 of the federal Species at Risk Act. The insular Newfoundland population of boreal caribou was assessed Not at Risk by COSEWIC (2002) and is therefore not included in this report. The forest tundra ecotype of woodland caribou is Not at Risk, and includes Leaf River, George River, Pen Island, Cape Churchill, and other populations on the northern Hudson Plain (COSEWIC, 2002). The forest tundra ecotype of woodland caribou is also not included in this report.

A boreal caribou local population is a group of caribou occupying a geographically distinct area that appears to be separate from other caribou groups (i.e., a boreal caribou herd). Local populations of boreal caribou are often characterized by having limited or no interaction or mixing with animals from other local populations (Environment Canada, 2008). However, local populations of boreal caribou are not necessarily genetically distinct (Environment Canada, 2007).

A boreal caribou local population range is a geographic area occupied by individuals of a local population that are subject to the same influences affecting population vital rates (such as, birth and death rates) (Environment Canada, 2008). In some cases, where local populations are restricted by natural geographic boundaries or habitat alteration they are considered to occur in discrete ranges (for example, many portions of caribou range in western Canada, Lake Superior shoreline of Ontario, Charlevoix in Quebec the isolated Charlevoix local population). In other cases, however, where local population ranges are not restricted by natural geographic boundaries or habitat alteration and are distributed across large areas of relatively continuous habitat, the distribution of boreal caribou occurs in continuous ranges (for example, northwestern and northeastern Ontario, central Quebec, and boreal taiga in the Northwest Territories). Future research and monitoring may enable managers to identify additional distinct local populations of boreal caribou within areas of continuous caribou distribution (Environment Canada, 2007). Range boundaries of local boreal caribou populations may be updated with changes in population size, vegetation (due for example to fire or other landscape disturbances), weather, and human activities (such as hunting and industrial developments) (COSEWIC, 2002). Range is thus a function of spatial extent and habitat conditions (Environment Canada, 2008).

Distribution

The range of the woodland caribou, including the boreal population, has retracted significantly from historical distributions. The southern limit of distribution has progressively receded in a northerly direction since the early 1900s (Figure 1), a trend that continues to the present day (Kelsall, 1984; COSEWIC, 2002; Schaefer and Mahoney, 2003; Vors et al., 2007). Pre-1830, woodland caribou resided in their original range across the boreal forest of North America north of 45o- 46o latitude (Banfield, 1961). Between 1839 and 1930, caribou disappeared from Nova Scotia, New Brunswick, Maine, Vermont, New Hampshire, Wisconsin, Michigan, and Minnesota (Bergerud and Mercer, 1989).

Woodland caribou are now distributed in the boreal forest in Canada across nine provinces and territories, from southwest Northwest Territories to Labrador, extending as far south as Lake Superior (Figure 1). Woodland caribou also occur in Alaska and Idaho/Washington. Boreal caribou are distributed throughout the boreal forest region in nine ecozones+: Arctic, Taiga Plains, Taiga Cordillera, Boreal Cordillera, Montane Cordillera, Boreal Plains, Taiga Shield, and Hudson Plains, and Boreal Shield (Environment Canada, 2008) (Appendix 2). The extent of occurrence of boreal caribou includes isolated or semi-isolated local populations (Figure 1).

Population Status and Trends

Boreal caribou are estimated to number 31,000 to 39,000 across their distribution in Canada (excluding the Island of Newfoundland), according to estimates provided by jurisdictions responsible for the management of boreal caribou across Canada (Environment Canada, 2008; see also Appendix 1). Using these data, 57 local population ranges of boreal caribou were recognized in the Scientific Review for the Identification of Critical Habitat for Woodland Caribou (Rangifer tarandus caribou), Boreal Population, in Canada (Environment Canada, 2008) (Figure 2). Of the 57 local populations 5.3% (n = 3) are increasing, 29.3% (n = 17) are declining, 28.1% (n = 16) are stable, and the status of the remaining 36.8% (n = 21) is unknown (Table 1).

 

Table  1. Estimated population trend of 57 local populations of boreal caribou in Canada.
Estimated Boreal Caribou Local Population Trend
  Declining Stable Increasing Unknown Total
Number of Local Populations 17 16 3 21 57
Percent (%) 29.8 28.1 5.3 36.8 100.0

Data provided by jurisdictions responsible for boreal caribou management across Canada.


Source: Environment Canada (2008)

Figure 1. The current extent of occurrence (distributino) of boreal caribou and the historical (early 1900s) extent of occurrence of woodland caribou (Rangifer tarandus caribou) in Canada.

Figure 1

Map does not depict the current extent of the Atlantic-Gaspésie or the insular Newfoundland populations.


Source: adapted from Environment Canada (2007)

Figure 2. Distribution of local populations of boreal caribou across their range in Canada (excluding the Island of Newfoundland).

Figure 2

Source: Environment Canada (2008)


Note that although several of the local populations may not be separate entities, they are considered to be distinct local populations for management purposes among jurisdictions. For example, until recently, local populations Deadwood in Alberta and Chinchaga in British Columbia were considered to be distinct local populations. They have recently been amalgamated and are both considered to be part of the Chinchaga local population. Since the writing of this report, the Ontario government has delineated preliminary ranges for 12 local populations as units of analysis for management of boreal caribou in Ontario, based on animal survey data, habitat information, and risk factors (Ontario Ministry of Natural Resources, 2009b). These data were not available at the time of writing this report, and thus are not included herein.

Some of the 57 local populations overlap ecozones+boundaries, thus for the purpose of this report, local populations are included in each of the ecozones+where they occurred. For example, if the range of a local population spanned two ecozones+, it was considered to be in both ecozones+with the same population trend data reported for both ecozones+. Note that the summaries in this report were made for the purposes of reporting on ecozones+, and thus differ slightly from summaries made on the 57 original local populations delineated in Environment Canada (2008). When reporting trends by ecozones+, results show 5.5% (n = 5) are increasing, 25.3% (n = 23) are declining, 28.6% (n = 26) are stable, and the status of 40.7% (n = 37) is unknown based on current trend data from the last 3 to 5 years.

The low sightability of boreal caribou from aircraft, their relatively solitary habits, and their range over thousands of square kilometres contribute to challenges in accurately determining population trends. In some areas of their distribution, detailed studies and monitoring efforts have produced precise population estimates; in other areas, population estimates are based on few data and are associated with a high degree of uncertainty. The quality of data for boreal caribou local population size and trend thus varies over most of the extent of occurrence, and in many instances is not well known. Appendix 1 provides notes on the intensity of population sampling effort and confidence limits of each local population estimate.

Arctic Ecozone+

Three boreal caribou local populations (or components thereof) occur in the Arctic Ecozone+. One local population is increasing and the status of the remaining two local populations is unknown (Figure 3).

Figure 3. Estimated population status of boreal caribou local populations in the Arctic.

Figure 3

 

Taiga Plains Ecozone+

Fifteen boreal caribou local populations (or components thereof) occur in the Taiga Plains Ecozone+. Of these, 33.3% (n = 5) are in decline, 6.7% (n = 1) are increasing, and the status of 60% (n = 9) is unknown (Figure 4).

Figure 4. Estimated population status of boreal caribou local populations in the Taiga Plains.

Figure 4

 

Taiga Cordillera Ecozone+

Three boreal caribou local populations (or components thereof) occur in the Taiga Cordillera Ecozone+. One local population is increasing, one is declining, and the status of the third local population is unknown (Figure 5).
 

Figure 5. Estimated population status of boreal caribou local populations in the Taiga Cordillera.

Figure 5


Boreal Cordillera Ecozone+

One local population (or component thereof) occurs in the Boreal Cordillera Ecozone+, and it is declining (Figure 6).

Figure 6. Estimated population status of boreal caribou local populations in the Boreal Cordillera. 

Figure 6


Montane Cordillera Ecozone+

One local population (or component thereof) occurs in the Montane Cordillera. This local population has had many years of documented population decline, but it is currently stable in response to implementation of an intensive wold population reduction program (Figure 7).

Figure 7. Estimated population status of boreal caribou local populations in the Montane Cordillera. 

Figure 7

 

Boreal Plains Ecozone+

Twenty-five local caribou populations (or component thereof) occurs in the Boreal Plains Ecozone+. Of these, 40% (n=10) are declining, 32% (n=8) are stable, and the status is unknown for 28% (n=7) of these populations (Figure 8).

Figure 8. Estimated population status of boreal caribou local populations in the Boreal Plains.

Figure 8