Biological Diversity Ecosystem Condition and Productivity Soil and Water Role in Global Ecological Cycles Economic and Social Benefits Society's Responsibility
Ecosystem Diversity Species Diversity Genetic Diversity
Indicator 1.2.1 Status of forest-associated species at risk Indicator 1.2.2 Population levels of selected forest-associated species Indicator 1.2.3 Distribution of selected forest-associated species Indicator 1.2.4 Number of invasive, alien forest-associated species
Indicator 1.2.3 - Distribution of selected forest-associated species
supporting indicator


The distribution of a species can expand, decrease, or spatially shift due to climatic fluctuations or other factors. Tracking the distributions of selected forestassociated species provides additional information to assess the state of forest biodiversity in Canada. Woodland caribou, American marten, pileated woodpecker, and northern goshawk have been selected as case studies because they play key ecological roles in forest ecosystems; they have demonstrated sensitivity to specific habitat requirements; their distribution is national; and long-term monitoring data are available.

CASE STUDY 1. Woodland caribou
(Rangifer tarandus caribou)
Woodland caribou was one of several indicator species reported on in the last report (CCFM 2000). The woodland caribou relies on relatively large and healthy areas of mature and old forest habitat, making this species sensitive to fragmentation and habitat loss. Given these characteristics, this species may be considered an indicator of forest connectivity. Other pressures include illegal hunting, disease and predation, anthropogenic disturbances such as industrial development or land use changes, and natural disturbances such as forest fires. The woodland caribou has steadily retreated from developed areas and now occupies only a small portion of its former range (Figure 1.2c). Several woodland caribou populations are currently listed under Schedule 1 of SARA. The woodland caribou has been extirpated from New Brunswick and Nova Scotia since the 1920s and from Prince Edward Island for several centuries. Since the last report, three of five populations of woodland caribou have been placed in a higher risk category (Table 1.2c) following COSEWIC reassessments.

Provincial, national, and international efforts to protect significant populations of the woodland caribou have been ongoing for over a decade. Many provinces have developed or are in the process of developing recovery and conservation strategies specific to the protection of this species. Conservation of some of the most susceptible populations has proven to be challenging given the numerous threats each population faces.

CASE STUDY 2. American marten
(Martes americana)
The American marten, an arboreal member of the weasel family of mammals, inhabits many of the forest regions of Canada (Figure 1.2d). There are two distinct populations of this species, the Newfoundland marten and the mainland marten, although other isolated populations probably exist on other islands such as offshore islands of British Columbia, Cape Breton, and Prince Edward Island (Kyle and Strobeck 2003).

Figure 1.2c

Figure 1.2c Distribution of woodland caribou in North America. (Source: CWS 2003b)

Table 1.2c Designations for five woodland caribou populations since their first assessment by COSEWIC in 1984. (Source: Adapted from COSEWIC 2002b)
Population name Province 1984 status 2000 (May) 2002 (May)
Pacific (Haida Gwaii) BC Extinct Extinct Extinct
Northern Mountaina YK, NWT, BC Rare Not at risk Special concern
Southern Mountaina BC, AB Rare Threatened Threatened
Boreala NWT, BC, AB, SK, MB, ON, QC, NL Rare Threatened Threatened
Newfoundland NL Not at risk Not at risk Not at risk
Atlantic (Gaspé) QC Threatened Endangered Endangered
a The northern and southern mountain populations were not recognized as separate populations by COSEWIC until May 2000. They were considered part of the boreal population.
Updated Data: PDF | Excel


Figure 1.2d

Figure 1.2d Distribution of American marten in North America. (Source: NatureServe 2004)

American marten are often associated with latesuccessional, coniferous forests throughout most of their range (Payer and Harrison 2003, COSEWIC 2004). Recent studies further suggest that other forest types at younger age classes, which are structurally capable of providing cover for prey habitat, protective thermal microenvironments, and protection from predators, may also be suitable habitat for this species (Poole et al. 2004). Given these characteristics, this species is sometimes considered an indicator of intact forest structure.

Main threats include loss of habitat structure through timber harvest or other silvicultural activities and overtrapping. Human disturbance, accidental captures in traps and snares set out for other species, predation, disease, and limited prey availability are additional contributing limiting factors.

Marten population numbers are fairly stable, but the Newfoundland marten was designated endangered by COSEWIC in 2000 and is currently listed under Schedule 1 of SARA. Marten were once found throughout Newfoundland, but the population has been declining since the beginning of the twentieth century. It now occurs only in small pockets of suitable mature forest habitat, primarily in western Newfoundland. Between 1980 and 1983 the population was estimated at 630 to 875 individuals. By 1998 population estimates indicated that only about 300 individuals remained. A small population has since been introduced into Terra Nova National Park in eastern Newfoundland.

Habitat requirements for American marten are often components of forest-management plans. In New Brunswick, for example, landscape scale objectives for provision of marten habitat require maintenance of some mature coniferous stands, leading to reduced allowable harvests in conifer-dominated forests. In boreal forests of Ontario, preservation of core habitat areas that include 80-year-old conifer-dominated stands is recommended for maintenance of healthy marten populations. British Columbia has specific objectives for marten under several regional land use plans. Both the Northwest Territories and the Yukon monitor trapping and conduct population research on marten. Conclusions on the impacts of the different conservation measures are limited, however, due to gaps in marten population information and the lack of marten monitoring programs throughout Canada.

CASE STUDY 3. Pileated woodpecker
(Dryocopus pileatus)
The pileated woodpecker is widely distributed and a year-round resident throughout much of Canada's forest (Figure 1.2e). This species prefers dead and decaying trees in both mixed and hardwood stands for cavity nesting and foraging. The pileated woodpecker plays an essential functional role by providing large cavities for a variety of wildlife (such as American marten) that depend on them for shelter, food storage, and reproduction. For this reason, it is considered to be a keystone species. The presence of pileated woodpeckers in the forest community may be a good indicator of forest structure, of the integrity of ecological functions, and of the wildlife communities that depend on these processes.

Figure 1.2e

Figure 1.2e Distribution of pileated woodpecker in North America on the basis of the Breeding Bird Survey Summer Distribution Map, 1994-2003. (Source: Sauer et al. 2004) Note: Although not covered by the Breeding Bird Survey, pileated woodpecker also occurs in southern Yukon and the Northwest Territories.

Silvicultural practices can reduce the availability of key structural components of pileated woodpecker habitat such as large decaying trees (Foothills Model Forest 2003). Fortunately, many provinces have implemented forest management objectives and guidelines that are capable of addressing the habitat needs of the pileated woodpecker. The Breeding Bird Survey population trend data (see Table 1.2b of Indicator 1.2.2) suggest that this species is doing well in Canada.

Case Study 4. Northern goshawk
(Accipiter gentilis)
The northern goshawk is a raptor that is widely distributed in both temperate and boreal forests and occurs over most of northern North America (Figure 1.2f). It can use a variety of habitats during the breeding season but prefers large forest stands with numerous mature to oldgrowth trees or stand characteristics (NatureServe 2004, CWS 2004c). The northern goshawk also requires a high canopy closure. Given these characteristics, it may be considered a promising candidate for indicating changes in forest structure and old growth in Canada.

Figure 1.2f

Figure 1.2f Distribution of the northern goshawk atricapillussubspecies (much of Canada) and the laingisubspecies (coastal British Columbia). (Adapted from CWS 2004c and the Canadian Biodiversity Web site, Redpath Museum)

Of the two subspecies that occur in Canada, the atricapillus subspecies is distributed through much of the country and is currently not considered at risk by COSEWIC. The laingi subspecies occurs only in coastal British Columbia, mainly on the Queen Charlotte Islands, Vancouver Island, and possibly on other large coastal islands. It is designated threatened by COSEWIC and is listed under Schedule 1 of SARA affording it special protection. The populations of the laingi subspecies are estimated to be between 300 and 425 breeding pairs throughout its range in British Columbia (Cooper and Chytyk 2001).

Recognizing the goshawk's sensitivity to changes in forest structure and old growth, several provinces have established their own monitoring programs and forest management guidelines to protect the northern goshawk and its habitat. In addition, a recovery team tasked to develop recovery strategies for the laingi subspecies has been formed in British Columbia.