78 Arctic Biodiversity Assessment Polar bears are iconic species of the Arctic, representing the fascination for wildlife in the cold northern region shared by people living in the Arctic as well as beyond. Photo: Wild Arctic Pictures/shutterstock.com 79 Chapter 3 Mammals 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 Contents Summary ............................................................... 80 3.6. Marine mammals ..................................................109 3.1. Introduction ........................................................ 81 3.6.1. Species richness and distribution ............................109 3.6.1.1. Status ...............................................109 3.2. Biogeography ...................................................... 82 3.6.1.2. Trends ..............................................112 3.2.1. Terrestrial mammals .......................................... 82 3.6.2. Population sizes and densities ...............................113 3.2.2. Marine mammals ............................................. 83 3.6.2.1. Status ................................................113 3.3. Terrestrial herbivorous mammals ................................... 85 3.6.2.2. Trends ..............................................117 3.3.1. Species richness and distribution ............................. 85 3.6.2.3. Causes and prospects ...............................119 3.3.1.1. Status ................................................ 85 3.7. Conclusions and recommendations ...............................121 3.3.1.2. Trends ................................................ 87 3.7.1. Valuable areas and productivity hotspots ....................121 3.3.1.3. Causes and prospects ................................ 88 3.7.2. Key knowledge gaps ........................................122 3.3.2. Population sizes and densities ................................ 90 3.7.3. Recommended conservation actions ........................123 3.3.2.1. Status ................................................ 90 3.7.4. Other key messages .........................................124 3.3.2.2. Trends ................................................ 92 3.3.2.3. Causes and prospects ................................ 97 Acknowledgements ....................................................124 3.4. Terrestrial insectivorous mammals ................................. 99 References .............................................................124 3.4.1. Species richness and distribution ............................100 3.4.1.1. Status ...............................................100 3.4.1.2. Trends ...............................................100 3.4.1.3. Causes and prospects ...............................100 3.4.2. Population sizes and densities ...............................100 3.4.2.1. Status ...............................................100 3.4.2.2. Trends ...............................................100 The bears are more hungry. There is a problem with the 3.4.2.3. Causes and prospects ...............................101 » ice. The rough ice makes it hard for them to find seals, 3.5. Terrestrial carnivorous mammals ..................................101 but there is the same number of seals. […] The only 3.5.1. Species richness and distribution .............................102 3.5.1.1. Status ...............................................102 change I’ve noticed is when I was growing up the polar 3.5.1.2. Trends ...............................................102 bears would scare easily and run away. Even when they 3.5.1.3. Causes and prospects ...............................104 were around shacks they didn’t break windows or do 3.5.2. Population sizes and densities ...............................104 damage but now they are not afraid. They used to avoid 3.5.2.1. Status ...............................................104 communities before and now they don’t. 3.5.2.2. Trends ...............................................106 3.5.2.3. Causes and prospects ...............................107 Dowsley 2007. 80 Arctic Biodiversity Assessment SUMMARY mercial interests have driven major declines in some populations of whales and reindeer, but intensive harvest There have been substantial changes during the past management has demonstrated that many populations can 50 years in the distribution and abundance of numer- recover, and that various species can sustain well-regulat- ous Arctic mammals. The intensity and scope of these ed harvests (e.g. whales, polar bears, seals, reindeer and changes have been more pronounced in marine than caribou, Arctic fox Vulpes lagopus). Indigenous peoples terrestrial mammals. However, the lack of quantitative have strong cultural and economic ties to the harvesting information for many species means that our assessment of mammals. These can be sustained with a combination is biased towards the larger, more conspicuous and more of cultural tradition and better science-based monitoring economically useful species. of population sizes and harvest levels. One set of changes is driven by a warming climate. Re- Humans have introduced or re-introduced populations ductions in the duration, extent and quality of sea ice of some species in the Arctic, considerably influencing are forcing ice-dependent mammals (notably polar bears their distributions and ecological roles. North American Ursus maritimus, seals and walrus Odobenus rosmarus) to species such as muskrat Ondatra zibethicus and American change feeding behavior and areas, change habitats for mink Neovison vison, introduced to Eurasia, have spread reproduction and resting, and often travel further, with into the low Arctic. Relocations of muskoxen have been consequent reductions in population productivity and successful in numerous circumpolar sites. We recom- size. Increased frequency of winter rain and melting mend against future introductions of mammals to previ- temperatures create ice cover on the ground or in the ously unoccupied ranges, especially islands, because of snowpack, making it more difficult for caribou/rein- uncertain and often disruptive ecological impacts. deer Rangifer tarandus and muskoxen Ovibos moschatus to reach food, and sometimes causing die-offs. Warming The Arctic is experiencing more human activity and temperatures are driving greater growth and spread of infrastructure developments at sea and on land in recent primarily shrubs, but also trees, transforming the low decades, as a result of hydrocarbon and mineral explo- Arctic tundra to sub-Arctic conditions with resultant in- ration and developments, new shipping routes, new flux of species (notably moose Alces americanus, Eurasian roads and increased tourism. These bring risks of direct elk Alces alces, American beaver Castor canadensis and mortality (e.g. oiling from spills, ship collisions), of dis- snowshoe hare Lepus americanus) that can use this new placement from critical habitats (e.g. calving, pupping habitat. Later onset of snow in autumn and earlier spring and feeding areas), of disturbance (e.g. aircraft, road melt shorten the duration and quality of the snow cover or ship noise interfering with whale feeding or caribou that is essential for lemming winter reproduction, and suckling), and of increased human harvests. are implicated in reduced amplitude and longer periods in lemming cycles, and therefore reduced availability of The following are high priority actions to mitigate the lemming prey for numerous predators. risks of increasing human activities: (1) an expanded system of protected areas or more intensively managed In addition to these patterns, other processes related to a zones, especially marine, with emphasis on coastlines, warming climate include: changes in the onset, duration polynyas, deltas, the edge of the ice pack, and caribou and amount of plant growth, changing distributions of calving grounds, (2) harmonized, cross-jurisdictional, ice-associated marine productivity, increased frequency regulatory and assessment regimes for ocean shipping, of boreal and tundra wild fires, changes in the relative aircraft routing, seismic and drilling activities, hydro- abundance of particular plant groups in tundra habitats, carbon and mineral developments and tourism, and (3) changing insect distribution and abundance, changing a more complete mammal distribution and abundance distributions of parasites and pests, together with more monitoring program designed to test alternative hypoth- extreme weather events and storms. These are likely to eses regarding mechanisms driving changes. have direct or indirect effects on the distribution, carry- ing capacity, productivity and ultimately population size Arctic carnivorous mammals, especially marine, have of various mammals (notably migratory tundra caribou increasing levels of contaminants, notably organochlo- and voles). However, at present we still lack sufficient rines and heavy metals, as a result of increased delivery information to draw strong inferences about causal of these substances