Polar Bear

Other PEMT sensitivity layers in this region:
Polar Bear | Bowhead Whale | Beluga | Ringed Seal | Peary Caribou
Migratory Birds | Traditional Hunting | Oil Spill Sensitivity

Summer
Polar Bear - Summer

Winter
Polar Bear - Winter

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You may also be interested in Polar Bear information in other PEMT regions:

High Arctic | Eastern Arctic

Valued Component Features

Key habitat

Polar bear distribution and habitat use in the Beaufort Sea varies with season. In winter (ice-covered season from October through April), most bears are actively hunting seals on areas of annual ice (ice that forms and melts annually). Areas within the Beaufort Sea that are most utilized for hunting include inter-island channels, and areas where ‘active ice' occurs, such as polynyas and landfast shore leads. The location of leads strongly influences the distribution of seals and polar bear hunting activity during winter. In the winter polar bears move south toward the shoreline of the mainland coast or Amundsen Gulf (Stirling 2002). The most important floe-edge and moving–ice habitats are distributed in a band through the Bathurst polynya. This intermediate zone of fractured, unconsolidated annual ice lies in shallow waters between the landfast ice along the coast and the multi-year pack ice further offshore (Stirling 1990).

Breeding occurs over relatively short periods during April and May, and adult females are concentrated in the best feeding habitat along the leads that parallel the coast. Males are drawn to these areas by the females' presence (Stirling et al. 1993). Most mating takes place on open sea ice. As the sea ice breaks up in the spring and early summer, polar bears follow the receding ice edge where seals occur. Where the ice melts completely during the summer months, most bears retreat off ice to denning locations on the North Slope of the Beaufort Sea and Banks Island, to den during the ice-free periods when prey is unavailable, or retreat northward to multi-year pack ice.

In early November, pregnant females dig maternity dens on land near the coast or offshore in the multi-year pack ice. Pregnant female bears may retire to maternity dens in late October to early November. These dens are found in snowdrifts on multiyear pack ice, but primarily on small islands near the western and southern shores of Banks Island, and to a lesser extent on islands and coastal areas from Tuktoyaktuk east to Alaska. Herschel Island appears to be the most important maternal denning area on the mainland coast (Stirling and Andriashek 1992). During periods of particularly cold or inclement weather, solitary males and females with cubs, may also shelter in dens on multiyear pack ice, within several hundred kilometres of the southern extent of pack ice (Stirling 2002).

Rationale for Selection

Polar bears are a high profile species for several reasons – they are a potential indicator species for measures of climate change, they provide social and economic benefits, and they are identified as a potential At-Risk Species (i.e., the area listed as Special Concern by COSEWIC). Canada supports a majority of the world's polar bear population and under the International Agreement on the Conservation of Polar Bears, the conservation of species is mandated. Additionally, the polar bear has previously been identified as an important component of the Nearshore Marine Valued Component in the recent Beaufort Delta Cumulative Effects Project (Dillon Consulting Limited and Salmo Consulting Limited 2005), the Marine Mammal Valued Component of the Northwest Territories Cumulative Impacts Monitoring Program, and within the Community Conservation Plans within the study area. Polar bears also provide direct economic support to the communities that provide consumptive (hunting) and non-consumptive (tourism and wildlife viewing) use of the bears. Thus, concerns about the status of the species exist at both regional and national levels.

Polar bear habitat in the Northwest Territories lies within the Inuvialuit land claim settlement area. Both the Government of the Northwest Territories (GNWT) and the Inuvialuit Final Agreement requires a review process for exploration, development, and research activities, which includes a consideration of impact on polar bear populations and other wildlife.

Sustainability

Polar bears are very closely tied to the presence of sea-ice from which they hunt, mate, and carry on other life functions. Maternal denning sites are a key element of bear ecology, potentially reducing the vulnerability of the cubs and nursing females to hunters and intraspecific predation. Historically, female polar bears were often hunted in maternal dens on Banks Island and the mainland, and the hunting of such bears may have contributed to the higher proportion of maternal denning sites currently found on multi-year pack ice off shore (Stirling 2002). However, declining ice extent and degrading ice character have been associated with a shift towards more land-based denning as availability and quality of pack ice denning habitat decreases (Fischbach et al. 2007). Further declines in sea ice availability and an increase in polar bears denning in coastal areas are predicted.

Susceptibility to development

In the eastern Beaufort Sea, most of the offshore drilling activity has been in shallower areas (<50 m) and there is overlap between the most important polar bear feeding habitat and offshore drilling activities (Stirling 1988). Large scale spills or blowouts during the fall or winter could affect prime breeding (see above) and foraging habitat. Oil, entrapped in ice, would eventually reach the floe edge and moving-ice habitats. There are likely two means whereby the viability of polar bear populations can be linked to project-specific impacts:

  • industrial activities may reduce the quality and amount of suitable habitat available to polar bears, especially for feeding and denning, and
  • industrial activities may increase the risk of mortality to individual bears in proximity to developments.

Habitat Susceptibility

The potential disturbance of denning and feeding areas could seriously affect the individual populations of polar bears (COSEWIC 2002). Industrial activity may produce residual effects that either result in a complete loss of habitat, as is common with the 'footprint' of industrial developments, or effective habitat loss, whereby polar bears avoid habitat in proximity to development. Depending upon the seasonality of occurrence of bears, and the timing of impacts, the habitat loss or avoidance that results from a specific project may be limited to specific seasons.

In the context of petroleum development and exploration, the maximum extent of predicted disturbance may extend up to 50 km from a point source impact (e.g., ice road construction and operations (Devon Canada Corporation 2004). Other oil and gas related projects would likely have more localized habitat impacts; flaring, drilling, and ice pad construction, may result in avoidance within approximately 1 km of a specific site. These localized disturbances may also result in avoidance of the site by two to seven seals (Devon Canada Corporation 2004), thus reducing foraging value for polar bears. The extent to which habitat losses from petroleum exploration and development may affect polar bear populations are uncertain, and will vary the amount, season, and duration of activities. In general though, it is unlikely that habitat loss from petroleum activity alone will directly influence populations, as mortality rate, and climate-induced habitat changes will most directly contribute to overall population trends.

The presence of oil or other contaminants resulting from accidents and malfunctions associated with petroleum exploration and fuel transfer also have the potential to reduce habitat availability. Contact with spilled oil may directly affect the health of individual bears, and/or reduce the availability of ringed seals. The population impacts that may result from such accidents would depend largely on the season, amount and type of contaminants released, climatic factors and the responses initiated.

Mortality Risk

Human-wildlife conflicts have occurred with regularity in areas where humans and bears coexist. For species such as polar bears, the loss of adult females in such conflicts poses a particular risk to the population. This is because polar bears have low reproductive rates, exist at low densities, and reproduce relatively late in life. High mortality rates of adult females would likely result in a relatively rapid population decline (i.e., within two to three generations).

Risk of mortality to bears is greatest where bears may interact with project facilities (on ice in particular) and bears could be killed to maintain the safety of humans. Polar bears, because of their highly investigative behaviour, may be attracted to project facilities (Stirling 1988), which could result in defensive kills if not properly monitored and mitigated. Mortality risk also extends to near shore developments that are in close proximity to denning locations (especially during freeze up) where bears initiate offshore hunting on areas of active and annual ice. In general, the frequency with which polar bears come into contact with people and structures is undoubtedly a function of the amount of activity in their habitats, and mortality risk increases in relation to human activity even when the best mitigation measures are put in place.

In the Beaufort Sea study area, the mortality risk that is directly associated with oil and gas projects has not been quantified. However, strict bear monitoring, waste management deterrence measures, and encounter protocols have reduced the mortality risks to bears (Devon Canada Corporation 2004).

Mitigation

Contaminant spills (particularly hydrocarbon spills) remain a potential risk that could have direct consequences to seal populations in the Beaufort Sea, and subsequently, to polar bear populations. This risk can be managed appropriately through prevention measures, and it can be considered to have a relatively low probability of occurrence. On-ice activities such as ice-platform based drilling, ice road construction, and flaring have the greatest potential for direct impacts to bears, either through habitat loss or increased mortality risk. Should development be initiated in areas where maternal dens are present, timing should coincide with the spring period when female bears are foraging away from maternal dens (from April to late spring). Females may occupy such dens during the open water season and during the birthing period (late October through to March or April).

Climate Change

The greatest overall threat to polar bears may be large-scale ecological change resulting from climatic warming (Stirling and Derocher 1993), which may change characteristics of sea ice. It is suspected that with a dramatic retreat of the pack ice, record amounts and duration of open water, and longer ice-free seasons that have predominated in this region in recent years, the amount of sea ice available as a substrate is reduced and bears spend less time in early summer and autumn travelling and foraging. With the progressive earlier breakup of sea ice and the shortened foraging season, bears are forced to come onshore earlier and this may result in nutritional stress that leads to intraspecific killing and consumption of polar bears in the southern Beaufort Sea (Amstrup et al. 2006, Stirling et al. 2008). Hence, climatic warming, longer ice-free periods and associated declines in Arctic sea ice lowers polar bear survival, and breeding and cub-of-the year survival declines (Monnett and Gleason 2006, Hunter et al. 2007, Regehr 2007, Rode et al. 2007).

Summer sensitivity scores

Summer (July - October)

With sea-ice breakup and a reduction in summer ice cover, polar bears in the Beaufort Sea either select habitats with a high proportion of old ice, which takes them northward as the ice melts or bears come ashore (Messier et al. 1994, Schliebe et al. 2008). Polar bears are excellent swimmers and swim while actively hunting, while moving between hunting areas, and while moving between sea ice and terrestrial habitats. Swimming is believed to be more energetically costly than walking, and bears often will abandon the melting ice in favour of land when ice concentrations drop below 50% (Derocher, Lunn, and Stirling, 2004).

Summer/Fall (July - October) Sensitivity

Low Sensitivity (1): areas that have very limited use year round, and thus, do not contribute substantially to the viability of the species in the area, in that the areas have little value for reproduction (denning) or survival (limited use for foraging). These areas are greater than 300 km beyond (i.e., northward) the summer extent of pack ice.

Low/Moderate Sensitivity (2): These areas represent parts of first year and multi-year pack ice that have limited use as foraging and denning areas (during the open water period primarily), and is the transition ice zone of predominantly first year ice that is bound by the multi-year ice to the north and the open water to the south (Dickins et al. 1987).

Moderate Sensitivity (3): These areas represent foraging areas in non-critical time periods (open water season) and include the summer limit of landfast ice to flow edge/moving ice area.

Moderate/High Sensitivity (4): These areas represent foraging areas in critical time periods of spring (May seal pupping period) and early fall (area of moving ice/flow edges, polynyas), as well as extensively used nearshore denning areas during open water times of limited prey availability.

High Sensitivity (5): Critical Habitat Areas are legally defined areas under the Species at Risk Act that represent habitats critically important to the survival of the species.

Winter sensitivity scores

Winter (November – June)

The location of leads strongly influences the distribution of seals and polar bear hunting activity during winter. In the winter polar bears move south toward the shoreline of the mainland coast or Amundsen Gulf (Stirling 2002). The most important floe-edge and moving–ice habitats are distributed in a band through the Bathurst polynya. This intermediate zone of fractured, unconsolidated annual ice lies in shallow waters between the landfast ice along the coast and the multi-year pack ice further offshore (Stirling 1990). In general, the polynya is visible as a distinct lead as early as March (Dickens et al. 1987). The maximum observed areal extent of the polynya during the period from April to June was used to establish a conservative set of boundaries for this zone for the winter/spring period (Dickens et al. 1987, Canadian Ice Service 2002). In the eastern Beaufort Sea, most of the offshore drilling activity has been in shallower areas (<50 m) and there is overlap between the most important polar bear feeding habitat and offshore drilling activities (Stirling 1988). Large scale spills or blowouts during the fall or winter could affect prime breeding (see above) and foraging habitat. Oil, entrapped in ice, would eventually reach the floe edge and moving-ice habitats.

Sensitivity areas in the winter are similar to the summer but also include the onshore and offshore maternity denning area. Maternal denning sites are a key element of bear ecology, potentially reducing the vulnerability of the cubs and nursing females to hunters and intraspecific predation. In early November, pregnant females dig maternity dens on land near the coast or offshore in the multi-year pack ice. Maternal dens located over broad regions of the Canadian Arctic were within 8 km of the coast (Harington 1968, Messier et al. 1994). Historically, female polar bears were often hunted in maternal dens on Banks Island and the mainland, and the hunting of such bears may have contributed to the higher proportion of maternal denning sites currently found on multi-year pack ice off shore (Stirling 2002). However, declining ice extent and degrading ice character have been associated with a shift towards more land-based denning as availability and quality of pack ice denning habitat decreases (Fischbach et al. 2007). Further declines in sea ice availability and an increase in polar bears denning in coastal areas are predicted. If the summer ice retreats far enough from shore and for a long enough time, it could prevent pregnant females that are foraging offshore from reaching the coast and bears will be forced to den in deteriorating pack-ice habitats (Fischbach et al. 2007). Should development be initiated in areas where maternal dens are present, timing should coincide with the spring period when female bears are foraging away from maternal dens (from April to late spring). Females may occupy such dens during the open water season and during the birthing period (late October through to March or April).

Winter (November - June) Sensitivity

Low Sensitivity (1): areas that have very limited use year round, and have little value for reproduction (denning) or survival (limited use for foraging).

Low/Moderate Sensitivity (2): These areas represent annual ice and multi-year pack ice that have limited use as denning and foraging areas.

Moderate Sensitivity (3): These areas represent foraging areas in non-critical time periods (November through early March) and is the transition ice zone of predominantly first year ice that extends from the northern boundary of the Bathurst Polynya and the southern boundary of the multi-year ice (Dickins et al.. 1987). Forage value of these areas is associated with the mid and early winter periods.

Moderate/High Sensitivity (4): These areas (moving ice/flow edges, polynyas) represent foraging areas in critical time periods in winter (mid March and April).

High Sensitivity (5): Critical Habitat Areas are legally defined areas under the Species at Risk Act that represent habitats critically important to the survival of the species. This includes extensively used nearshore denning areas used during early winter to early spring (November through April) for birthing. With reductions in stable old ice, increases in unconsolidated ice, and lengthening of the melt season, the proportion of polar bears denning in coastal areas will continue to increase, until such time as the autumn ice retreats far enough from shore that it precludes offshore pregnant females from reaching the coast in advance of denning.

Summary

Polar bears were considered a VEC because of their high public profile, economic importance, and importance within the food chain as the top predator in the Beaufort Sea. A higher sensitivity rating was most often associated with denning and foraging areas in critical time periods. Due to seasonal changes in polar bear distribution and habitat uses, it is recommended that a long-term view of the potential activities be considered when evaluating individual grids. Although oil and gas exploration activities may be limited to seasons when bears are not present (such as open water seismic), the potential petroleum production infrastructure associated with such exploration – which is the ultimate goal of exploration activities – may ultimately persist year round, and could impact polar bear populations beyond the season(s) of exploration.

Specific recommendations regarding project seasonality and other mitigation measures should be a component of project-specific planning and/or impact assessment. Ongoing efforts to identify and map areas where polar bears are most likely to den and forage should also improve the ability of regulators and industry to reduce disturbance of denned bears (effective habitat loss) and reduce the likelihood of conflict-related bear kills (mortality risk).

References

See references used for polar bear information.