Wild species 2010: chapter 25

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Mammals

Mammalia - Class of vertebrates that contains any warm-blooded animals, members of which are characterized by the possession of mammary glands and a four-chambered heart, including human beings, carnivores, ungulates, rodents, whales, etc.

Quick facts

• There are more than 5000 known species of mammals, divided into 26 orders. The rodents are the largest order of mammals in the world, both in terms of number of species, and number of individuals.
• A total of 218 species of mammal have been found in Canada, including 169 species ranked in the provinces and territories and 49 ranked in the ocean regions.
• When excluding species ranked as Extinct, Extirpated, Undetermined, Not Assessed, Exotic or Accidental, the majority (72%) of mammals in Canada have Canada General Status Ranks (Canada ranks) of Secure, while 16% have Canada ranks of Sensitive, 6% have Canada ranks of At Risk and 6% have Canada ranks of May Be At Risk.
• One species of mammals is extirpated from Canada and one species that used to be present in Canada is now Extinct.
• Most changes in the general status ranks of mammals in Wild Species 2010 were due to taxonomic changes or COSEWIC detailed assessments.
• The world’s largest mammal is the Blue Whale (Balaenoptera musculus), which can grow up to 25 m long and weigh up to 100 tonnes.

Background

From the Atlantic Walrus (Odobenus rosmarus) of the frozen Arctic, to the American Bison (Bison bison) of the prairies, to the Red Squirrel (Tamiasciurus hudsonicus) in your backyard or local park, mammals are a familiar and diverse group found throughout Canada. Mammals are able to endure Canada’s varied and sometimes harsh climate because they are warm-blooded (endothermic). This means that mammals are able to keep their core body temperature stable, despite outside temperature fluctuations. Mammals are believed to have evolved from a group of reptiles, called the synapsids, more than 200 million years ago, slightly before the dinosaurs appeared on earth. Since the disappearance of the dinosaurs, about 65 million years ago, mammals have spread and diversified to reach their present, global distribution.

One of the defining characteristics of mammals is the possession of hair, from the short, velvety hair of the Townsend’s Mole (Scapanus townsendii), to the thick, shaggy coat of the Muskox (Ovibos moschatus). The most important function of hair is to provide insulation from the cold. For example, the hair of the Arctic Fox (Vulpes lagopus) provides such efficient insulation that they can remain active even at temperatures below -50°C! Some mammals loose their hair as adults, so they use other methods of insulation. For example, Cetaceans (whales, dolphins and porpoises) which loose their hair soon after birth, are insulated by a thick layer of blubber. Other important uses of hair include camouflage (e.g. the white, winter coat of the Snowshoe Hare, Lepus americanus) and communication (e.g. the White-tailed Deer, Odocoileus virginianus, uses its white tail to flash a danger signal as it runs from a predator). There are two main types of hair, underfur and guardfur, each with its own function. The thick, soft underfur traps a layer of warm air to insulate the body, while the guardfur acts to protect the underfur. The long, soft underfur of the Muskox is one of the most luxurious and expensive natural fibres in the world.
All female mammals possess mammary glands, which produce milk to feed their young. Milk is rich in proteins and fat, and provides the young with the nutrients and energy they need to develop and grow. While they depend on their mother for milk, the young develop social behaviours and learn about their environment, including which foods are good to eat and how to find them. Some mammals, such as the Caribou (Rangifer tarandus), give birth to precocial young, which are well developed and can run almost immediately after birth. Young Caribou stagger to their feet less than an hour after birth, and can run fast enough to keep up with the herd within the first day or two of life. In contrast, altricial young are born helpless, often blind, and with very limited mobility. For example, Eastern Grey Squirrels (Sciurus carolinensis) are born naked and toothless, and their eyes and ears are scarcely visible. It takes over a month before their eyes begin to open, and almost two months before they venture outside the nest.

Some of Canada’s most distinctive mammals are those that live in the Arctic tundra, including the Polar Bear (Ursus maritimus), Arctic Fox, Caribou, Muskox, and several different types of lemming. While some of these mammals, such as the Caribou, migrate south during the winter, many are resident on the tundra year round. Arctic mammals show many adaptations to the extreme cold, including thick fur coats and high metabolic rates. Several Arctic mammals, such as the Muskox and Polar Bear, have evolved a large size and compact shape to reduce heat loss. Small mammals, such as the Northern Bog Lemming (Synaptomys borealis) spend the winter under the snow. Deep snow acts as an insulating layer, protecting the lemmings from extreme surface temperatures. Many Arctic mammals keep their extremities at temperatures close to freezing while their core body temperature does not fluctuate. For example, the temperature of a Caribou’s legs can be as much as 10°C cooler than its core body temperature. This is accomplished by a special arrangement of blood vessels that allow the warmth of the blood being pumped to the extremities to heat the blood returning to the core (this system is called counter-current heat exchange). Only one Arctic mammal, the Arctic Ground Squirrel (Spermophilus parryii), undergoes true hibernation, during which its body temperature drops far below normal.

Status of knowledge

In general, mammals in Canada have been well-studied, and the basic biology and physiology, distribution and ecology of many mammal species are well understood. In recent years, technological advances including satellite telemetry and new genetic tools have been used to further improve knowledge of Canadian mammals. However, there remain challenges that make studying mammals in the wild difficult, including nocturnal or secretive behaviour, remote distribution, difficulty in handling wild mammals and the vast distances covered by some large mammals. In addition, many marine mammals can be difficult to study due to the long time spent under water, and the short time spent at the surface.

A major focus of mammalogy in Canada has been studies of large mammals, such as Caribou, Wapiti (also known as Elk, Cervus elaphus) and Polar Bears. Large mammals are important to study because of their economic value, potential for conflict with humans and their importance in the ecosystems in which they live. For example, recent research in Banff National Park has shown that by controlling the Wapiti population, Grey Wolves (Canis lupus) have an indirect impact on the local vegetation structure and bird communities. In areas of high Grey Wolf density, there are fewer Wapiti, more regenerating vegetation, more warblers and fewer sparrows. Studies like this demonstrate the importance of large mammals in shaping their local ecosystems.

Tracking mammals at sea is a difficult task, and can limit research on deep-sea marine mammals, but new technology, including satellite tracking, satellite remote sensing and acoustic remote sensing, is helping to improve knowledge in this area. For example, Blue Whale (Balaenoptera musculus) migration and habitat use has been followed using acoustic and satellite remote sensing, allowing continuous, large-scale, spatial and temporal tracking of Blue Whale movements for the first time.

In general, mammals that are not considered economically or culturally important (such as shrews, family Soricidae), have not been studied as well as large, charismatic or economically important mammals, like the Polar Bear or Caribou. For example, bats (order Chiroptera) are generally less well-studied and less well understood than many other mammal groups, and the distribution, ecology and life history of some bats in Canada is still poorly known. However, new studies are starting to close this gap. For example, recent surveys in Nova Scotia discovered Canada’s first known breeding colony of Eastern Pipistrelles (Pipistrellus subflavus). Other recent bat studies have focussed on habitat use, echolocation, diet and thermal ecology of bats.

Richness and diversity in Canada

There are nine orders of mammals in Canada, of which the rodents (Order Rodentia), is by far the most species rich. Of Canada’s 218 mammal species, 169 are ranked only in the provinces and territories and 49 are ranked only in the ocean regions. British Columbia (119 species, figure 25) has the highest species richness of mammals in Canada, due primarily to high numbers of insectivores (order Insectivora) and bats (order Chiroptera) found in the province.

The majority of Canada’s 49 species of marine mammals are found in the Atlantic Ocean Region (32 species) or the Pacific Ocean Region (30 species, figure 25).

Species spotlight - Northern Long-eared Myotis

The Northern Long-eared Myotis (Myotis septentrionalis) is a medium-sized bat found in all the provinces and territories except Nunavut. Like all Canada’s bats, the Northern Long-eared Myotis is nocturnal; during the day it roosts under the peeling bark of decaying trees and at night it hunts for insects. The Northern Long-eared Myotis uses two main hunting techniques; catching insects that are resting on trees and bushes (gleaning) and catching insects in flight (hawking). In both cases, the Northern Long-eared Myotis uses echolocation to detect its prey. These bats are active only during the warmer months of the year (approximately April to September). During the rest of the year, they hibernate in caves or abandoned mines where the humidity is high and the temperature hovers just above freezing.

The nocturnal and secretive behaviour of the Northern Long-eared Myotis make this species difficult to study, but new technology is increasing the ability of scientists to investigate bat habitat use. For example, researchers can set up microphones in different habitats to record the sounds made by feeding bats. Since different species of bats make different sounds, computer programs can analyse the recordings and find out which species are feeding in which habitat type. In addition, by capturing bats and attaching tiny radio-transmitters, researchers can find out exactly which trees bats prefer to roost in. Results from these studies show that mature forest habitat, with large decaying coniferous and deciduous trees is important for these bats. This kind of information helps foresters and wildlife mangers make informed decisions about which types of habitat should be conserved to support healthy bat populations. Leaving individual mature deciduous and coniferous trees as well as patches of intact mature forest in harvested landscapes may help support Northern Long-eared Myotis populations. In turn, bats can help to control outbreaks of forest pests, such as Spruce Budworm (Choristoneura fumiferana).

The Northern Long-eared Myotis is more common in eastern and central Canada (ranked Secure or Sensitive) than in western and northern Canada (ranked May Be At Risk or Undetermined). This is due its preference for mature mixed wood forest, which is more widely available in eastern Canada, as well as the availability of suitable hibernation sites and climate. Due to its large range in Canada, Northern Long-eared Myotis has a Canada General Status Rank (Canada rank) of Secure.

Species spotlight - Northern Bottlenose Whale

The Northern Bottlenose Whale (Hyperoodon ampullatus) is named for its dolphin-like beak and prominent “egg-head” forehead, which is particularly large in adult males. They are found in the northern Atlantic Ocean, where they favour deep, cool water. Northern Bottlenose Whales are very sociable animals, and live in small groups, or pods. Males are larger than females and can reach up to 10 m in length, and weigh up to 7.5 tonnes! In males, the lower jaw of the beak holds two small teeth, but the female has no teeth at all. Northern Bottlenose Whales dive up to 1000 m in depth for as long as 70 minutes, searching for their favourite food of squid (genus Gonatus).

Two distinct populations of Northern Bottlenose Whales are found in Canada; one off the northern Labrador coast (Davis Strait population) and another off the southeast coast of Nova Scotia (Scotian Shelf population), within the Atlantic Oceanic Region. The Scotian Shelf population lives within an underwater canyon called The Gully. This population of about 130 animals has a unique migratory strategy and life history compared to other bottlenose whale populations.

Northern Bottlenose Whales were hunted for centuries for their spermaceti oil, which was used to make high quality lubricating oil and candles. Bottlenose whales were easy prey for whale hunters because they are attracted to boats by their intense curiosity. Pod-members are extremely protective of injured or distressed companions, so whalers were often able to harvest the majority of the pod, before the remaining members dived for safety. By the mid 1970’s global populations of Northern Bottlenose Whales were reduced to vulnerable levels. In 1973 commercial hunting ceased and in 1977 the species was classified as a protected species by the International Whaling Committee, but global populations of Northern Bottlenose Whales have not yet fully recovered. In Canada, the Davis Strait population is currently assessed as Not At Risk by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC), but the Scotian Shelf population was assessed by COSEWIC as Endangered in 2002, and is now protected under Canada’s Species at Risk Act.

Fortunately for researchers, the Northern Bottlenose Whale’s sociable nature has made the study of its biology and behaviours relatively easy, since observers are able to approach the whales without disturbing them. The Gully, home of the Scotian Shelf population of Northern Bottlenose Whales, is a Marine Protected Area, but is surrounded by oil and gas discoveries and is close to trans-Atlantic shipping routes. Recent research in this area has attempted to determine the effects of human activities on the whales, including commercial shipping, fishing activity, and the offshore oil and gas industry. The Northern Bottlenose Whale has a Canada general status rank of Sensitive; this has not changed since Wild Species 2000.

Species spotlight - Common Grey Fox

Common Grey Foxes (Urocyon cinereoargenteus) are the only member of the dog family (family Canidae) in Canada with the ability to climb trees! This small fox has short legs and long, strong back claws that allow it to scramble up tree trunks to escape from predators or look for food, such as fruit, birds and rodents. On the ground, Common Grey Foxes also eat rabbits and other small mammals. Slightly smaller and greyer in colour that the Red Fox (Vulpes vulpes), Common Grey Foxes are native to Ontario and have also been recorded in New Brunswick, Quebec, Manitoba and Alberta.

Common Grey Foxes have an intriguing history in Canada. Archaeological records from the villages of Aboriginal Peoples indicate that in the past, Common Grey Foxes were almost as abundant as Red Foxes in southern Ontario. However, the records of European settlers make no mention of this unusual species. In fact it wasn’t until early in the 1890s that Common Grey Foxes were reported first in Quebec, and then in Ontario. No one is certain what caused Common Grey Foxes to disappear from Ontario for more than 300 years, or why they have become re-established over the past 100 years. However, it has been suggested that warmer temperatures in recent years have allowed northern populations, like those in southern Ontario, to survive and increase. Today, the only place in Canada where Common Grey Foxes are known to breed is Pelee Island in southern Ontario. Records of Common Grey Foxes in other parts of Ontario and in southern Manitoba are probably single individuals that have travelled across the border from the United States, where Common Grey Foxes remain widespread.

Due to its small range and small population size in Canada, and because its forested habitat is under threat from human development, Common Grey Fox has a Canada rank of At Risk. This rank has changed from Not Assessed in the report Wild Species 2000, due to an updated COSEWIC status assessment of Threatened.

Results of general status assessment

The majority of mammals have Canada ranks of Secure (62%, 135 species, figure 25 and table 36). However, 13% have Canada ranks of Sensitive (29 species), 6% have Canada ranks of At Risk (12 species), 5% have Canada ranks of May Be At Risk (11 species), and a total of 1% have Canada ranks of Extirpated (one species, Black-footed Ferret, Mustela nigripes) and Extinct (one species, Sea Mink, Neovison macrodon). In addition, 5% of mammal species have Canada ranks of Exotic (11 species), 5% have Canada ranks of Undetermined (11 species), and 3% have Canada ranks of Accidental (seven species).

Comparison with previous Wild Species reports

Since the last assessment in 2005, the total number of mammal species remained stable (table 36). However, a total of 11 species had a change in their Canada rank. Among these changes, two species had an increased level of risk, two species had a reduced level of risk, three species were changed from the rank Undetermined, two species were added and two species were deleted. Most changes in the general status ranks of mammals in the Wild Species 2010 report are due to taxonomic changes, to improved knowledge of the species, and to new COSEWIC detailed assessments (table 37).

Threats to Canadian mammals

Mammals are a large and varied group, and the threats facing them are similarly varied. Habitat loss, fragmentation and degradation are important threats for many mammal species, especially large mammals, habitat specialists and mammals whose range overlaps areas of dense human habitation. Other threats to Canadian mammals include overexploitation, disease, exotic species, hybridization and climate change.

Lack of information on mammals such as bats and shrews make it also difficult to detect or reverse population declines. For example, the white-nose syndrome in bats represents an important concern. This syndrome is characterized by the presence of white fungal growth on muzzles, ears, or wing membranes of affected bats. It affects bats that hibernate in caves, including the common Little Brown Bat (Myotis lucifugus). Since the winter of 2006-2007, massive mortalities of bats were observed in the north-eastern states of the United States. The disease has spread rapidly; and in early 2010, it was first confirmed in Ontario and Quebec. No one knows where white-nose syndrome came from, but one theory is that it was inadvertently transported by people from Europe. Emerging diseases such as white-nose syndrome are an example of how the conservation status could potentially change even for very common species.

Marine mammals typically face a different set of threats to freshwater and terrestrial mammals. In particular, human activities at sea can often be harmful to marine mammals. Two of the greatest threats are entanglements with fishing gear and collisions with boats. In addition, from petroleum activity, such as seismic exploration, and commercial ship traffic may cause physical damage to marine mammal hearing or interfere with their feeding, migration or communication. Commercial ship traffic is responsible for much of the noise pollution found in the world’s oceans today. Considerable work remains to be completed to explore these impacts more fully.

Exposure of marine mammals to pollutants has been much publicised. For example, the resident Killer Whales (Orcinus orca) of the Pacific coast are among the most contaminated marine mammals in the world. Marine mammals are vulnerable to pollutants for several reasons including their position at, or close to, the top of the food chain, and their long life cycles. Marine mammals generally do not metabolise pollutants well. Instead they are stored in the blubber, from where they can be passed to the young during suckling, or to predators, including humans. Marine mammals with high levels of contamination can face reduced survival and suppression of the immune system leading to increased rates of disease. However, it if difficult to make direct links between high levels of contamination and population declines.

Conclusion

Compared to terrestrial and freshwater mammals, the proportion of marine mammals ranked Secure is low, and the proportion of marine mammals with Canada ranks of At Risk, Sensitive or Undetermined is high. This reflects both the increased risks faced by marine mammals, as well how much more we need to learn about marine ecosystems and the species that live there.

This updated general status assessment of mammals allowed the general status national mammal lists to be updated with the latest scientific knowledge. The Canada ranks of most of the mammal species were not changed, resulting that the overall proportion of mammal species in each of the general status categories has not changed substantially over the last assessments.

Further information

Banfield, A. W. F. 1977. The mammals of Canada. University of Toronto Press, Toronto, Ontario: 438 pp.

Cetacean Research & Rescue Unit. Bottlenose whale (Hyperoodon ampullatus). (Accessed February 16, 2010).

Fisheries and Oceans Canada. 2006. Observatoire du Saint-Laurent / St. Lawrence Observatory. Marine mammal research. (Accessed February 16, 2010).

Fisheries and Oceans Canada. 2005. Arctic marine mammal ecology and assessment research section. (Accessed February 16, 2010).

Fisheries and Oceans Canada. 2005. Cetacean research program (Accessed February 16, 2010).

Fisheries and Oceans Canada. 2004. Aquatic species at risk - Killer Whale, Northeast Pacific transient population. (Accessed February 16, 2010).

Fisheries and Oceans Canada. 2004. Aquatic species at risk - Northern Bottlenose Whale, Scotian Shelf population. (Accessed February 16, 2010).

Forsyth, A. 1985. Mammals of the Canadian wild. Camden House, Camden East, Ontario: 351 pp.

Gaskin, D. E. 1972. Whales, dolphins and seals. Heinemann educational books, Auckland: 200 pp.

Hebridean Whale and Dolphin Trust. Northern Bottlenose Whale, Hyperoodon ampullatus. (Accessed February 16, 2010).

Jansa, S. 1999. Urocyon cinereoargenteus. Animal Diversity Web. (Accessed February 16, 2010).

MarineBio.org. 2005. Northern bottlenose whale - Hyperoodon ampullatus. (Accessed February 16, 2010).

Ollendorff, J. 2002. Myotis septentrionalis. Animal Diversity Web. (Accessed February 16, 2010).

Savage, A. and Savage, C. 1981. Wild mammals of western Canada. Western Producer Prairie Book, Saskatoon, Saskatchewan: 209 pp.

References

Barber, K. (editor). 1998. The Canadian Oxford Dictionary. Oxford University Press. Toronto, Oxford, New York: 1707 pp.

Broders, H. G. and Forbes, G. J. 2004. Interspecific and intersexual variation in roost-site selection of northern long-eared and little brown bats in the Greater Fundy National Park ecosystem. Journal of Wildlife Management 68: 602-610.

Broders, H. G., Quinn, G. M. and Forbes, G. J. 2003 Species status, and the spatial and temporal patterns of activity of bats in southwest Nova Scotia, Canada. Northeastern Naturalist 10: 383-398.

Burtenshaw, J. C., Oleson, E. M., Hildebrand, J. A., McDonald, M. A., Andrew, R. K., Howe, B. M. and Mercer, J. A. 2004. Acoustic and satellite remote sensing of blue whale seasonality and habitat in the Northeast Pacific. Deep-Sea Research II 51: 967-986.

Caceres, M. C. and Pybus, M. J. 1997. Status of the northern long-eared bat (Myotis septentrionalis) in Alberta. Alberta Environmental Protection, Wildlife Management Division, Wildlife Status Report No. 3, Edmonton, Alberta: 19 pp.

COSEWIC. 2002. COSEWIC assessment and update status report on the grey fox Urocyon cinereoargenteus interior in Canada. Committee on the Status of Endangered Wildlife in Canada, Ottawa: 32 pp.

COSEWIC. 2002. COSEWIC assessment and update status report on the northern bottlenose whale Hyperoodon ampullatus (Scotian shelf population) in Canada. Committee on the Status of Endangered Wildlife in Canada, Ottawa: 22 pp.

Fuller, T. K. and Cypher, B. L. 2004. Grey Fox, Urocyon cinereoargenteus. In Canids: Foxes, wolves, jackals and dogs, status survey and conservation action plan (C. Sillero-Zubiri, M. Hoffmann and D. W. Macdonald, editors). IUCN/SSC Canid Specialist Group. Gland, Switzerland and Cambridge: 430 pp.

Hebblewhite, M., White, C. A., Nietvelt, C. G., McKenzie, J. A., Hurd, T. E., Fryxell, J. M., Bayley, S. E. and Paquet, P. C. 2005. Human activity mediates a trophic cascade caused by wolves. Ecology 86: 2135-2144.

Jung, T. S., Thompson, I. D. and Titman, R. D. 2004. Roost site selection by forest-dwelling male Myotis in central Ontario, Canada. Forest Ecology and Management 202: 325-335.

Patriquin, K. J. and Barclay, R. M. R. 2003. Foraging by bats in cleared, thinned and unharvested boreal forest. Journal of Applied Ecology 40: 646-657.