MAMMALS (Chapter 3)

Lead Authors:  Donald G. Reid, Dominique Berteaux and Kristin L. Laidre 

Contributing Authors: Anders Angerbjörn, Robyn Angliss, Erik W. Born, Peter Boveng, Dean Cluff, Dorothee Ehrich, Steven H. Ferguson, Joel Garlich-Miller, Gilles Gauthier, Anne Gunn, Kit M. Kovacs, Nicolas Lecomte, Lloyd F. Lowry, Philip McLoughlin, Dennis Litovka, Sue Moore, Kaisu Mustonen, Tero Mustonen, Linh Nguyen, Elizabeth Peacock, Kim Poole, Lori Quakenbush, Don Russell, Niels M. Schmidt, Boris Sheftel, Michael Simpkins, Benoit Sittler, Brian Slough, Andrew Smith, Fernando Ugarte, Dag Vongraven and Øystein Wiig

SUMMARY

There have been substantial changes during the past 50 years in the distribution and abundance of numerous Arctic mammals. The intensity and scope of these changes have been more pronounced in marine than terrestrial mammals. However, the lack of quantitative information for many species means that our assessment is biased towards the larger, more conspicuous and more economically useful species.

One set of changes is driven by a warming climate. Reductions in the duration, extent and quality of sea ice are forcing ice-dependent mammals (notably polar bears Ursus maritimus, seals and walrus Odobenus rosmarus) to change feeding behavior and areas, change habitats for reproduction and resting, and often travel further, with consequent reductions in population productivity and size. Increased frequency of winter rain and melting temperatures create ice cover on the ground or in the snowpack, making it more difficult for caribou/reindeer Rangifer tarandus and muskoxen Ovibos moschatus to reach food, and sometimes causing die-offs. Warming temperatures are driving greater growth and spread of primarily shrubs, but also trees, transforming the low Arctic tundra to sub-Arctic conditions with resultant influx of species (notably moose Alces americanus, Eurasian elk Alces alces, American beaver Castor canadensis and snowshoe hare Lepus americanus) that can use this new habitat. Later onset of snow in autumn and earlier spring melt shorten the duration and quality of the snow cover that is essential for lemming winter reproduction, and are implicated in reduced amplitude and longer periods in lemming cycles, and therefore reduced availability of lemming prey for numerous predators.

The bears are more hungry. There is a problem with the ice. The rough ice makes it hard for them to find seals, but there is the same number of seals. […] The only change I’ve noticed is when I was growing up the polar bears would scare easily and run away. Even when they were around shacks they didn’t break windows or do damage but now they are not afraid. They used to avoid communities before and now they don’t. Dowsley 2007.

In addition to these patterns, other processes related to a warming climate include: changes in the onset, duration and amount of plant growth, changing distributions of ice-associated marine productivity, increased frequency of boreal and tundra wild fires, changes in the relative abundance of particular plant groups in tundra habitats, changing insect distribution and abundance, changing distributions of parasites and pests, together with more extreme weather events and storms. These are likely to have direct or indirect effects on the distribution, carrying capacity, productivity and ultimately population size of various mammals (notably migratory tundra caribou and voles). However, at present we still lack sufficient information to draw strong inferences about causal mechanisms between these acknowledged climate patterns and mammal distributions and demography.

Ecological changes related to a warming climate are happening so fast and are so pervasive that stabilization and major reductions in emissions of greenhouse gases, at the global scale, are the highest priority conservation action for the Arctic.

A second set of changes is driven by human activities. Harvesting of Arctic mammals has a long history. Commercial interests have driven major declines in some populations of whales and reindeer, but intensive harvest management has demonstrated that many populations can recover, and that various species can sustain well-regulated harvests (e.g. whales, polar bears, seals, reindeer and caribou, Arctic fox Vulpes lagopus). Indigenous peoples have strong cultural and economic ties to the harvesting of mammals. These can be sustained with a combination of cultural tradition and better science-based monitoring of population sizes and harvest levels.

Humans have introduced or re-introduced populations of some species in the Arctic, considerably inf luencing their distributions and ecological roles. North American species such as muskrat Ondatra zibethicus and American mink Neovison vison, introduced to Eurasia, have spread into the low Arctic. Relocations of muskoxen have been successful in numerous circumpolar sites. We recommend against future introductions of mammals to previously unoccupied ranges, especially islands, because of uncertain and often disruptive ecological impacts.

The Arctic is experiencing more human activity and infrastructure developments at sea and on land in recent decades, as a result of hydrocarbon and mineral exploration and developments, new shipping routes, new roads and increased tourism. These bring risks of direct mortality (e.g. oiling from spills, ship collisions), of displacement from critical habitats (e.g. calving, pupping and feeding areas), of disturbance (e.g. aircraft, road or ship noise interfering with whale feeding or caribou suckling), and of increased human harvests.

The following are high priority actions to mitigate the risks of increasing human activities:

• (1) an expanded system of protected areas or more intensively managed zones, especially marine, with emphasis on coastlines, polynyas, deltas, the edge of the ice pack, and caribou calving grounds,
• (2) harmonized, cross-jurisdictional, regulatory and assessment regimes for ocean shipping, aircraft routing, seismic and drilling activities, hydrocarbon and mineral developments and tourism, and
• (3) a more complete mammal distribution and abundance monitoring program designed to test alternative hypotheses regarding mechanisms driving changes.

Arctic carnivorous mammals, especially marine, have increasing levels of contaminants, notably organochlorines and heavy metals, as a result of increased delivery of these substances to the Arctic food web as airborne pollutants or in runoff from freshwater Arctic drainages. There is little evidence of demographic consequences in wild mammals to date, but a growing need to better understand the origins of pollutants, with internationally coordinated efforts to reduce them at source.

The relative impact of current changes varies by species and biogeographic region. However, most changes have been, and will continue to be, in the low Arctic regions. This is where human activity is more intense, and where the most dramatic terrestrial and marine habitat changes are taking place. Oceans pose an insurmountable barrier to any northward expansion of smaller-bodied terrestrial species currently confined to Arctic mainland, and these will experience the most significant range restrictions. Likewise many expanding boreal species within continental Eurasia and North America will be stopped by ocean barriers, and will be unable to reach the Arctic islands. This particular isolation of islands, such as the Canadian archipelago, Novaya Zemlya and Severnaya Zemlya, to novel colonization by smaller mammals allows these islands to act as partial refuges for their existing mammal fauna in the face of climate-driven changes in distribution.

INTRODUCTION

Relatively few mammals occur in the Arctic. About 67 species of terrestrial mammals and 35 species of marine mammals occupy this biome, at least seasonally (Appendix 3.1), comprising about 2% of global mammalian diversity. This low percentage ref lects the energetic constraints facing homeotherms in this environment, and the fact that large areas were covered in ice through various ice ages, and as recently as 7,000-14,000 years ago (Dyke 2004). As climates warmed in the late Pleistocene and the Holocene (i.e. the last c. 12,000 years), Arctic tundras changed in distribution and composition. Mammals redistributed themselves, evolved to the new conditions, or became extinct probably as a result of a complex combination of climate changes and hunting by humans (Lorenzen et al. 2011). The Arctic is now home to species belonging to the following mammalian orders: Rodentia (rodents), Lagomorpha (hares and pikas), Soricomorpha (shrews), Carnivora (dogs, bears, cats, weasels, walruses and seals), Artiodactyla (even-toed ungulates) and Cetacea (porpoises and whales). All of these are characteristic north temperate latitude groups, but representatives of two other such mammalian orders – Erinaceomorpha (hedgehogs) and Chiroptera (bats), both insectivorous – have not colonized Arctic latitudes in the Holocene.

The Arctic biome is generally defined in a terrestrial context, as tundra habitats where trees do not grow (see Section 2 in Meltofte et al., Introduction for this Assessment’s delineations of low and high Arctic). Such a tree-line is imprecise in definition, and the sub-Arctic includes extensive shrub tundra interspersed with trees (northern taiga forest). We include terrestrial species with predominantly boreal, including sub-Arctic, distributions whose habitat affinities and documented distributions include some of the low Arctic. For marine ecosystems there is nothing equivalent to the treeline to allow a convenient ecological definition of ‘Arctic’. We discuss in detail those species with a well-documented and consistent occupation of marine areas encompassed by low and high Arctic. We do not discuss species using sub-Arctic marine waters. We also acknowledge the occasional occurrence of other species within low Arctic waters (Appendix 3.2). The taxonomy of Arctic mammals is fairly well studied, partly because there are relatively few species. However, there are still some uncertainties, especially among the rodents, shrews and hares. Pleistocene isolation in different refugia, and Holocene isolation following sea level rise, may or may not have led to sufficient genetic differentiation to warrant species status (Jarrell & Fredga 1993, Edingsaas et al. 2004, Wilson & Reeder 2005, Hope et al. 2011). For this assessment we follow the nomenclature in Wilson & Reeder (2005).

The broad distributions of Arctic mammal species are fairly well known, especially for conspicuous and recognizable larger-bodied species, although the amount of fine-scale information on distribution varies by species. Our confidence in the broad distributions of small-bodied species (all terrestrial) is high. These patterns are largely extrapolated from locations of well-documented presence and absence, and consider likely barriers to dispersal (mainly stretches of ocean and major rivers). However, the detailed distributions of these small-bodied species remain poorly documented, because the animals are inconspicuous and have not been surveyed in a widespread and repeated fashion through this very extensive and relatively inaccessible biome. We rely on various standard sources for broad distribution patterns (Wilson & Reeder 2005, Andreev et al. 2006, MacDonald & Cook 2009, IUCN 2011), and also on detailed data from species experts.

We present the diversity of Arctic mammals as species richness within various geographic regions (Appendix 3.1). For terrestrial mammals, regional boundaries are primarily water bodies (oceans and large rivers) that coincide with the boundaries of distributions of a number of species, leading to a strong inference that the water bodies played a role in geographic isolation and, sometimes, speciation (e.g. Ehrich et al. 2000, Waltari et al. 2004). Occasionally, we also employ jurisdictional boundaries to define regions (e.g. Fennoscandia). For marine mammals, we present species richness within 12 marine regions defined generally by seas or archipelagos with some bathymetric or geographic separations.

The quality of information on abundance varies a great deal among species and regions. Some mammals are central to the well-being of northern peoples as sources of spiritual meaning, food, income from hunting and trapping and as competitors. These relationships can be very old, and deeply embedded in northern cultures. Vyacheslav Shadrin, a Yughagir elder from Kolyma region of Siberia says:

…when there is an earthquake, we say that the mammoth are running. We even have a word for this, holgot (Mustonen 2009).

Some species attract scientific attention because they are key players in the food web or have particular conservation concerns. However, we have very little or no detailed information for numerous other terrestrial and marine species. In addition, there is a relative lack of accessible, published information for species occurring in Russia.

We present current knowledge on distributions, richness and abundance by species or population, depending on the detail available. We organize this information in four broad sections:

• (1) terrestrial herbivorous mammals,
• (2) terrestrial insectivorous mammals,
• (3) terrestrial carnivorous mammals, and
• (4) marine mammals.

CONCLUSIONS AND RECOMMENDATIONS

Valuable areas and productivity hotspots

Three types of habitat are particularly valuable due to their unique biological richness and large-scale influence on Arctic ecosystems: caribou calving grounds, coastal zones and margins of the sea ice-pack.

Migratory tundra caribou calving grounds require special attention. Caribou choose these fairly restricted ar eas because of high food quality and relatively low predation risk, and thereby maximize the survival and vigor of calves. Human activities and infrastructure (e.g. aircraft f light paths, roads, off-road vehicle use, pipelines) should be prohibited or strongly regulated in these landscapes during the calving seasons when the activities can readily disrupt the optimum bonding and behavior of cows and calves with negative consequences for calf recruitment. Calving grounds are site-specific by herd, though they do shift somewhat over time. Many are currently undergoing some mineral and hydrocarbon exploration and road development (e.g. Beverly) or are under such threat (e.g. Bathurst, Porcupine).

Coastal zones, especially over the relatively shallow continental shelf and banks, are particularly productive marine areas. Along coastlines, the mixing of marine water with nutrient-rich fresh water, from land-based drainages and melting sea ice, enhances productivity and attracts large concentrations of marine mammals. Migratory marine mammals rely on this spatially-concentrated ocean productivity for foraging opportunities. Deltas and offshore plumes from the major rivers (notably the Mackenzie and Lena) are heavily used feeding areas. Coastlines and nearshore ice and barrier islands are particularly important for polar bears, combining high-value habitats for reproduction and resting with relatively high marine productivity especially in spring and summer. Coastal zones are particularly at risk because expanding human activities (e.g. shipping, fishing, oil and gas developments, transportation infrastructure and settlements) are and will be concentrated in and beside these zones of high ecological productivity and easier access to resources.

Sea ice margins are also particularly productive marine areas that attract numerous marine and some terrestrial mammals. They include the geographically widespread ice margins of the Bering/Chukchi Seas, Baffin Bay, Davis Strait, E Greenland and the Barents Sea. These zones change position somewhat between years as patterns of ice melt change, and are likely to shift systematically in response to changing climate. Nevertheless, they require particular attention because of their importance to many marine mammals.

In winter, a particular set of sea ice margins is found at polynyas or flaw leads, where substantial areas of water remain open or only occasionally frozen due to particular combinations of wind and currents. These are important habitats for winter-resident Arctic marine and terrestrial mammals as well as seabirds. They are seasonally delimited habitats, requiring particular conservation attention in winter. Key examples of polynyas include North Water (N Baffin Bay), St. Lawrence Island (Bering Sea) and North East Water (NE coast Greenland); and of flaw leads include NE Chukchi Sea, Cape Bathurst (Beaufort Sea) and Laptev Sea.

While managers need to pay attention to habitats of high ecological value, conservation attention also needs to be focused on biological ‘hotspots’ that overlap areas of particular interest to oil, gas and mining industries, because of the increased disturbance that is likely to occur in those areas. These tend to be geographically large areas in the exploration phase, leading to site-specific developments.

Four regions appear to be of particular interest to the oil and gas industry at present: Barents Sea, Beaufort-Chukchi Seas, Baffin Bay and E Greenland. These regions deserve particular attention because the exploration, development and production phases of this industry may cause displacement of species from important feeding or breeding habitats, changes in the underwater acoustic environment, impacts to calving and migratory habitats, and potentially direct mortality or changes in vital rates due to collisions, oil spills or contamination. The risks of population declines for both marine and terrestrial mammals can only be addressed, and perhaps mitigated, through environmental assessments (including collection of new data not already available to resource managers); controls on the intensity, timing and structure of exploration and development activities; and dedicated work with local communities to ensure the implementation of cautious management and harvest plans for mammals that might be affected. Given the paucity of data on many Arctic mammal populations, it is difficult to detect population changes and attribute their cause to either human-induced or natural factors. Therefore, strengthened research and monitoring programs must precede and accompany proposed development activities in Arctic regions.

The global rush for minerals is resulting in many new mine developments in the Arctic. Each potential new mine site requires focused attention to determine its potential direct and indirect impact on terrestrial mammals. Marine mammals may also be impacted by increased shipping and activity in coastal zones, and various other factors resulting from industrial development and its infrastructure. Concerted efforts must be made to forecast the impact of any one development project, as well as the cumulative impacts in a particular region. Environmental impact assessments are a necessary component of our management, but the ability of these assessments to consider multiple scales of potential impacts over both time and space is limited and must be improved. Special attention should be given to the use of new technologies that reduce the extent of infrastructure required (e.g. air ships), and to operational measures that reduce the potential for changing mammal behavior (e.g. proper garbage management, controls on human harvesting of wildlife). Monitoring of Arctic mammals and potential impacts on them must be an integral and funded portion of any developments.

Key knowledge gaps

One major conclusion of this review is that detailed, long-term data on population trends for Arctic mammals are rare. There are no abundance or trend estimates for many key populations and species of marine (e.g. all of the ice-dependent pinniped populations and several polar bear populations) and terrestrial (e.g. Arctic wolf, many lemming populations) mammals. Demographic data are also absent for many species, and if available they are rarely of high quality. This is largely explained by high costs and logistical hurdles of monitoring populations in large and remote areas. Information on population trends is important for natural resource managers to take management actions when populations face single or cumulative impacts, and to measure recovery from any perturbation. Good population monitoring is the first requirement for biodiversity assessment, and our knowledge of the status and trends of Arctic species will remain relatively poor unless we invest more resources into monitoring their numbers and understanding their ecology.

Weather patterns and extreme weather events are prominent limiting factors for Arctic herbivores. Global climate patterns, such as the North Atlantic and Arctic Oscillations, affect seasonal weather patterns and therefore timing and productivity of plant growth over multi-annual and decadal periods. These relationships deserve increased attention including investigations of patterns in a greater diversity of weather-related phenomena that impact mammals (e.g. freezing rain and icing events, thaw-freeze cycles in winter, timing of snowmelt, timing of snow onset, taiga and tundra wild-fire frequency). Such investigations need to be coupled with long-term studies of how such weather phenomena are affecting demographic parameters in mammals (e.g. over-winter survival and reproductive output in rodents and lagomorphs, conception and calf survival in caribou and muskoxen). Northern community members who are nfrequently on the land can be employed in recording patterns of weather, especially unusual events, and animal responses (see Huntington, Chapter 19, for discussion of community-based monitoring).

Caribou herd viability, and the ability to monitor herds, depend on a good understanding of locations and temporal use of calving grounds by reproductive and barren cows. For some herds, this information is still unclear, but is crucial when population monitoring depends on calving ground counts. Improved mapping and tracking of calving grounds and the landscapes used by barren cows in the same season will allow more robust population estimation, and improved application of land management guidelines.

Cumulative impacts assessments of multiple direct and indirect anthropogenic activities over space and time need improvement. Given a general lack of predictive models for cumulative impacts assessment, we need new approaches to both detecting negative effects as quickly as possible, and combining effects in decision-making. For caribou, one approach lies in monitoring herd status by sampling individual health status (pregnancy rates, body condition, parasite load, and survival) integrated in energy allocation models (Russell et al. 2005), coupled with research on relationships between herd status and environmental factors such as weather, snow and fire.

Recommended conservation actions

The most urgent conservation need is a stabilization and reduction of greenhouse gases at the global scale, so that climate change can be slowed and limited in intensity worldwide. Continued increases in greenhouse gas production, mostly outside the Arctic, will exacerbate the ongoing disruption of Arctic ecosystem processes. Climate warming in the Arctic has had the most dramatic effects on snow, ice and water (the cryosphere) (AMAP 2011). These are prominent components of Arctic habitats, and consequently some Arctic mammal populations that are economically and culturally important will be significantly reduced in distribution and abundance. Icessociated mammals, especially polar bear and pinnipeds, are highly threatened by reductions in duration of the sea ice season and in spatial extent of summer ice. Some populations are at high risk of extirpation within decades. The probability of global extinction of an Arctic mammal species has not been estimated, but appears to be growing with the increasing pace of habitat and ecosystem change.

The variety of legislation, regulations and policies across the circumpolar Arctic needs to be harmonized, ideally with the assistance of the Arctic Council. Environmental legislation and regulations vary in strength and intensity across jurisdictions. These include: (1) environmental impact assessment for major industrial projects, (2) endangered species protection, (3) harvest management, (4) marine transportation safety, pollution and routing regulations, (5) offshore oil and gas drilling and extraction standards, and (6) identification of responsibility for providing resources for necessary studies before new anthropogenic activities occur. Without such harmonization, the level of environmental risk and consequent negative impact on a population will vary from jurisdiction to jurisdiction and negative impacts in one region will affect other regions. For example, some jurisdictions require substantial environmental impact assessments where the risks to impacted mammal populations are minimized with mitigation measures imposed; other jurisdictions lack a robust assessment process. Transboundary populations may experience relatively heavy negative impacts in a jurisdiction with weaker legislation and regulations, despite strong conservation efforts in a jurisdiction with higher environmental standards. The chances of one jurisdiction suffering the consequences of poorer environmental standards in another jurisdiction will continue to increase as development proceeds.

A coordinated mammal population abundance monitoring plan needs to be developed, and implemented in the field, with the support of jurisdictions. Strategic attention should be focused on specific combinations of species and region from which most inferences can be drawn. Such a plan needs to build on long-term data sets and requires integration with existing local or national monitoring through the circumpolar Arctic. Particular attention to monitoring in Eurasia is warranted. Such monitoring plans have already been discussed for marine mammals such as belugas, ringed seals and polar bears, but none has actually been fully developed or implemented. Migratory tundra caribou are the subject of an international monitoring effort (CircumArctic Rangifer Monitoring and Assessment Network (CARMA)), but many other species are currently overlooked.

The Circumpolar Biodiversity Monitoring Program (CBMP) is a valuable start to the large task of archiving, reporting and making accessible data on population distribution and abundance for Arctic species. This program needs to be maintained and supported in its goal of better integration with field-based monitoring programs. However, merely tracking population size and demographic parameters is not enough. Monitoring must be designed to test alternative hypotheses about the role of limiting factors (e.g. weather, primary production, disturbance, harvest) on distribution and abundance. Hypotheses explaining past, present and future changes must be set and tested as integral parts of monitoring activities. Maximizing the number of counted populations is not as important as investigating limiting factors in conjunction with following a suite of strategically chosen populations.

In conjunction with abundance monitoring, all user groups need to collaborate in improved monitoring and record keeping of animal harvest levels across jurisdictions, so the sustainability of the total harvest can be assessed for biological populations. Harvest of wildlife is a critical component of human subsistence in the Arctic. Harvest can be a factor in population declines, and science-based harvest management can reduce the risk of population collapse and ensure that subsistence resources are available for future generations. Some components of these harvests are monitored by scientific or co-management committees. However, some are not monitored at all, and many of them involve transboundary populations. Harmonization of harvest reporting and documentation across jurisdictions would improve conservation and management regimes.

Previously depleted populations of harvested Arctic mammal species, and of species currently well below historical levels, need to be recovered wherever possible, especially where there is high likelihood that excessive human harvesting was (e.g. SW Greenland beluga), or still is (e.g. W Greenland walrus), a major factor in reducing abundance. The international moratorium on commercial whaling appears to have facilitated the recovery of some bowhead whale sub-populations (George et al. 2004, Heide-Jørgensen et al. 2007). Harvest restrictions also can assist caribou population recovery at low density, but the inherently cyclic nature of caribou population abundance confounds the definition of a targeted abundance for recovery and complicates the suite of management actions to facilitate recovery.

There is an urgent need for the establishment of a comprehensive set of protected areas, based on eco-regional representation, biodiversity hotspot analyses, the subsistence economy of northern peoples, and climate change risk assessment. Protected areas with minimal human activity are valuable as ecological benchmarks for understanding ecological processes and as refuge areas during key seasonal periods in the life cycle. If chosen well they can also be relative refuges from the effects of climate change. Northern peoples often harvest mammals in traditional areas related to animal concentrations and accessibility, and precluding other developments to maintain harvests in these areas is a strong rationale for protection. There are a considerable number of land-based protected areas, but relatively few marine protected areas in the Arctic. As climate change is known to be causing environmental changes throughout Arctic ecosystems, some administrative flexibility is needed to ensure that protected areas can be modified or adaptively managed to continue to cover the necessary areas, both now and in the future. Protected areas have spatial but also potentially temporal dimensions. For example, calving grounds of migratory tundra caribou need strong protection during the calving season, but could conceivably sustain some human activities and functioning infrastructure in other seasons. 

Other key messages

Many Arctic mammal populations are co-managed between national or sub-national government agencies and indigenous government or community agencies. Knowledge derived from both community experience and scientific studies are expected to contribute to decision making. Smooth decision making has been thwarted in some cases by breakdowns in communication and trust. Solutions are not always clear, but do depend on open-mindedness, honest communication and joint realization that the sustainability of the population is a shared goal of all involved.

Scientific understanding of the direct and indirect effects of climate change and other stressors on Arctic ecosystems is still in its infancy. Society’s ability to manage change and implement a valid conservation agenda depends on increased funding for both hypothesis-driven monitoring and basic research into factors driving the distribution and abundance of Arctic mammals.

The Arctic encompasses many of the last wilderness regions on the planet, with species that are marvels of adaptation to difficult conditions, and ingenious human cultures that are intimately linked to harvesting mammals. Conserving the biological and cultural diversity of the Arctic deserves society’s utmost efforts and attention in these changing times.