Field Guide/Natural History Mammals of Montana Kerry R. Foresman photographs by This comprehensive guide details the taxonomy, ecology, behavior, reproductive biology, and distribution of all 109 mammal species in Montana, from the pygmy shrew, one of the tiniest mammals in the world, to the bison, the largest land mammal in North America. Whether you want to distinguish between the 15 species of bats that live in or migrate through the state or are simply trying to identify the squirrel in your backyard, Mammals of Montana is for you. This second edition contains more than 500 color photographs, many by renowned wildlife photographer Alex Badyaev. Scattered throughout the species descriptions are interesting and curious facts about these wild creatures. Learn which shrew is venomous, how the pika survives winter in its alpine habitat without hibernating, and what animal squeezes through vole tunnels in search of dinner.Author Kerry Foresman also covers the reintroduction efforts to save Montana species, such as the black-footed ferret and swift fox, from extinction, and he cautions how climate change may push others, such as the northern bog lemming and wolverine, to the brink. P U B L I S H I N G CO M PA N Y P.O. Box 2399 • Missoula, MT 59806 • 406-728-1900 800-234-5308 • info @mtnpress.com www.mountain-press.com $32.00 Kerry R. Foresman photographs by Alexander V. Badyaev Foresman Mountain Press Mammals of Montana Alexander V. Badyaev Mountain Press Second Edition P U B L I S H I N G CO M PA N Y P.O. Box 2399 • Missoula, MT 59806 • 406-728-1900
m M P C I c Lateral jaw view Lateral skull view I C i P c M p m R R L L Dorsal jaw view.; I (i) = incisors, C (c) = canines, P (p) = premolars, M (m) = molars. Ventral skull view. Dotted arrow identifies hidden, very small molar M3 [Mountain lion shown]. premolars and molars may be combined and the formula written as i 1/1, c 0/0, P+M 5/4, total 22. In shrews, it is not even entirely clear what the developmental history of the singlecusped teeth is; here the choice has been to designate such teeth as unicuspids and group them together. For the pygmy shrew the formula would be written i 3/1, u 5/0, p 1/2, m 3/3, total 36. Many additional pattern variations exist that are beyond the scope of this book. For a more detailed discussion, refer to the companion text: Key to the Mammals of Montana. Common External Measurements. When specimens are captured or collected, five body measurements are commonly taken: total length, tail length, length of the hind foot, ear length, and body mass. Introduction 9
Tail length (Ta): Distance from base of tail to end of vertebral column (excluding the extended hairs) Length of hind foot (HF): Distance from heal to end of longest claw Ear length (E): Distance from base of notch in ear to tip (excluding any hairs)
in a handling bag as shown under the section below on mammal observations; large species, such as the grizzly bear shown here, may be hung from a scale supported by a tripod. Such standard field measurements, obtained from museum records and field studies, are provided for each species. Where possible, values from a representative sample of ten adults were averaged. Measurements of males and females were combined, where similar; if sexual dimorphism occurs (males and females are consistently different sizes), measurements for both sexes are given. Attempts were made to provide measurements from Montana specimens but, where not available, measurements from other regions were used. Physiography of Montana Montana is a land of contrasts. It is the fourth largest state in the union, relinquishing honors only to Alaska, Texas, and California, with a land mass of 147,042 square miles (380,848 km2), nearly 94 million ac (38 million ha). It lies between 45o and 49o north latitude, placing it squarely within the montane coniferous forest biome. Of this acreage, one-fourth, nearly 2.3 million ac (9.3 million ha), is forested. The remaining three-fourths of the land is dispersed among four other climatic zones: alpine, subalpine, grasslands, and semidesert. An elevational gradient within the state runs from 1,800 feet (550 m) in the northwest corner, where the Kootenai River enters Idaho, to the 12,799 feet (3,902 m) summit of Granite Peak in the Beartooth Mountains of south-central Montana. The state is characterized by mountainous terrain, a majority of which lies in the western one-third of the state and serves as the backbone to the Continental Divide. The Rocky Mountain chain that runs through Montana formed toward the end of the Cretaceous Period of the Mesozoic Era 70 to 90 million years ago. Several mountain ranges, such as the Bears Paw, Big Snowy, and Crazy mountains, however, are isolated in the central part of the state. These latter mountain ranges formed more recently, about 50 million years ago, during the Eocene Epoch of the Tertiary Period. Introduction 11
dry spells. The combination of uplifting of the continental crust, and sedimentation brought on by soil erosion and the inability of weakly flowing streams to carry suspended materials away, led to filling of the valley floors. Many mammalian species became isolated on these mountain ranges, unable to disperse across the intervening wide-open, lower grasslands. During the more recent geologic history of the state, a series of glacial events greatly influenced distribution of plant and animal communities. Within the past 200,000 years of the Pleistocene Era, two major ice ages occurred in Montana. The first, termed the Bull Lake Glacial Period, occurred roughly 130,000 years ago.The Laurentide and Cordilleran ice sheets extended across Canada just north of Montana and moved southward to cover the valley floors of the northern part of the state. Higher mountain glaciers also formed on elevated regions of the Beartooth Plateau and what is now Yellowstone National Park. These ice sheets receded only to be followed by a second, more recent ice age called the Pinedale Glaciation, which reached its maximum between 22,000 and 18,000 years ago. These glacial events not only shaped the mountains of western Montana, as is clearly evident in the Mission Mountains just north of Missoula, but they greatly influenced distribution of mammalian populations. Larger species, such as caribou (Rangifer tarandus) and bighorn sheep (Ovis canadensis), could readily travel at the front of the forming ice sheet, only to move northward again as the interglacial warming periods occurred. Smaller species may have survived in this manner as well, although they also may have chosen to retreat to the mountain peaks that remained free of ice. In many instances, as conditions warmed and the ice sheets receded, plants and smaller animal species unable to migrate over long distances were left as isolated populations. Species adapted to colder conditions may have been unable to migrate down from their mountain refugia and cross now inhospitable valley floors. Pockets of habitat reminiscent of these colder periods also may have been left as glaciers retreated northward, forcing species adapted to these conditions to remain. These events often explain the present day distributions of mammals that we see, such as the glacial remnant, the northern bog lemming (Synaptomys borealis). More than eighty-eight mountain peaks in Montana exceed 11,000 feet (3,353 m), all but thirteen of which lie in the Beartooth Mountains in the south-central part of the state. An additional 498 peaks exceed 10,00 feet (3,077 m), over one-fourth of which are found in the Absaroka Range, directly west of the Beartooth Range and north of Yellowstone National 12 Introduction
Ice Sheet Mountain Glaciers Laurentide Ice Sheet M O N TA N A Mountain Glaciers Yellowstone Plateau W YO M I N G IDAHO Extent of ice and glacial lakes during major glacial events in Montana over the past 130,000 years Elevational map of Montana showing the extensive topographical features Introduction 13
s is M tns tn M Lew h e a d M t an Fl a Sw Mission Mtns fish ite s WhMtn lish Sa ns Mt B ll t ne r ce Pu t n s a b i n s C Mt M Mo u n t ains ot d n l at i G al tns on M dis Ma tns M ly el av n s Gr Mt a he er av t n s Be M Pi o Mtneer ns tn M Little Sheep Mtns g Sh ee Highwood Mtns te Rattlesnake rro Mtns G a Mtrnet ns Flint Elkhorn Mtns Mtns Crazy ad Bridger Mtns onlar Mtns a c nt s An Pi t n Tobacco M Root P Absaroka Mtns M r yo Mtns tn r s Beartooth Mtns S app h Mtnsire p in as cc t n s o M M Judith Mtns Little Belt Mtns Big Snowy Mtns Castle Mtns s Little Rocky Mtns Bi Bears Paw Mtns lt Be s Big tn M it Sweet Grass Hills Bi Rosebud Mtns M gho tn rn s Centennial Mtns Major mountain ranges that define Montana Park. Interspersed between these mountain ranges lie broad, high-elevation valley systems most of which, particularly in the central and southwestern regions, range between 4,039 feet (1,231 m) and 6,562 feet (2,000 m). Native plant communities in these areas are technically classified as steppe grasslands due to the minimal annual rainfall they receive. Indeed many of the plant species are similar, if not identical to, those found throughout the steppe highlands of the Tibetan Plateau of northwestern China, a region lying at a similar latitude. From the peaks of these mountains, through high elevation plateaus, several major river systems form that dramatically dissect the state. The most famous of these are the Jefferson, Madison, and Gallatin that converge at Three Forks to form the Missouri, and the Yellowstone, which drains Yellowstone Lake, flowing northward from the national park to merge with the Missouri just across the Montana–North Dakota border. This system ultimately flows into the Gulf of Mexico. In the west-central part of the state, the Bitterroot and Blackfoot rivers converge with the Clark Fork in Missoula, ultimately draining into the Columbia and the Pacific Ocean. Another smaller system forms in Glacier National Park and drains northeastward into Waterton Lake, then to the Saskatchewan River, finally flowing into Hudson Bay. Water coming off Triple Divide Peak in Glacier can find its way into any of these three systems, and the entire region is termed the Crown of the Continent. Extremely hot temperatures occur in summer in Montana, particularly in the arid southeast where temperatures in excess of 100.4oF (38oC) are common. Bone-chilling temperatures in the winter are not uncommon (a record temperature of -69.8oF [-21oC] was recorded on Rodgers Pass in 1954). The northwestern region is influenced by coastal air masses from the Pacific and is thus milder and moister. The north-central region, which lies on the opposite side of the Continental Divide, routinely suffers under arctic air blasts that sweep down across the mountains of British Columbia and the plains of Alberta. These airflow patterns, and the annual amount and regional distribution of rainfall received, have greatly influenced the vegetative characteristics of the state. Climatological and physical features, coupled with one of the lowest population densities in the country [2.6 persons/0.4 mi2 (/km2)], have shaped the floral community we see today. 14 Introduction
NORTH-CENTRAL NORTHWESTERN NORTHEASTERN CENTRAL WEST-CENTRAL SOUTHEASTERN SOUTHWESTERN SOUTH-CENTRAL Sagebrush Forests Riparian and wetlands Alpine Grasslands Semi-desert Vegetation map of Montana.The eight forest regions are outlined in red. Introduction 15
Fleepit Digital © 2021