Biology 306 - MAMMALOGY LABORATORY

Laboratory 2: ORDER CARNIVORA - Family Mustelidae

The Family Mustelidae is comprised of 23 recent genera totaling 64 species distributed nearly worldwide. Of the 11 North American genera 7 occur commonly in Montana. You should examine skins and skulls of the following mustelid species:

Martes americana (American marten)

Martes pennanti (fisher)

Gulo gulo (wolverine)

Mustela frenata (long-tailed weasel) [summer and winter pelts]

Mustela erminea (short-tailed weasel or ermine) [summer and winter pelts]

Mustela nivalis (least weasel - the smallest member of this family)

Mustela vison (mink)

Taxidea taxus (badger)

Mephitis mephitis (striped skunk)

Spilogale gracilis (western spotted skunk)

Lutra canadensis (river otter)

In order to distinguish between M. frenata and M. erminea you must calculate the ratio between the postglenoid length (PGL) of the skull and the condylobasal length (CBL) (refer to the illustration of these measurements on the skull drawing below): if PG/CBL > 47% ~ M. erminea < 47% ~ M. frenata

Three of the above species, M. frenata, M. erminea, and M. nivalis undergo coloration changes between winter and summer months [refer to the figure from W.J. Hamilton, Jr., American Mammals (1939) below].

Look at these changes in the specimens in the laboratory. Become familiar with the general life histories of these species [particularly their habitat associations and breeding pattern]. A recent popular Natural History article outlines the current problems in the black- footed ferret population: "Decline and fall of the black-footed ferret" by David Weinberg, February, 1986, and two summaries of the current research being conducted can be found in Miller et al. (1988). Biology of the endangered blackfooted ferret and the role of captive propagation in its conservation. Can. J. Zool. 66, 765-773, and Tim Clark (1989). Conservation Biology of the Black-footed ferret, Musteia nigripes. Wildlife Preservation Trust Special Scientific Report No. 3. Additional information is displayed in the hall display case and further discussions will occur in lecture. A general overview of the reproductive patterns in this family is presented in Mead, R.A. and Wright, P.L. (1983). Reproductive cycles of Mustelidae. Acta. Zool. Fennica 174, 169-172. This paper is available in the laboratory and is on reserve in the library.

Characterize the dentition of members of this family. Determine the dental formula of each of these species? [How were you able to make these determinations?] Many male mustelids can be aged by the development of the baculum (os penis) and the development of the sagittal crest. Look at the bacula placed out in lab and pay particular attention to the sagittal crest of the fisher (compare males and females).

Considerable interest has arisen recently in these "forest carnivores"; their distribution and general status are now the subject of many surveys. Look at the methods and protocols being developed for these surveys, as shown in the lab; particularly the use of remote-sensing camera units and tracking plates, and the type of information these provide. Additional information on these aging methods can be found in Techniques Paper #2 and on the survey methods in Techniques Paper #3, in your faculty pack.

Biology 306 - MAMMALOGY LABORATORY

Laboratory 3: ORDER CARNIVORA - Family Canidae

The Family Canidae is comprised of 16 recent genera totaling 36 species distributed throughout the world with the exception of Antarctica (species have been introduced into many formally unoccupied regions). Of the 4 North American genera 2 occur commonly in Montana.

You should examine skins and skulls of the following canids:

Canis lupus (gray wolf)

Canis latrans (coyote)

Canis familiaris (domestic dog)

Vulpes vulpes (red fox)

Urocyon cinereoargenteus (gray fox; not found in Montana)

Alopex lagopus (arctic fox; not found in Montana)

The swift fox (Vulpes velox) (now considered synonymous with the kit fox) was historically found in the state but was considered extirpated by approximately 1918. Since the late 1970's animals have begun to find their way back into the state from populations near Gillette, Wyoming and more recent reintroduction efforts in Alberta and Saskatchewan beginning in 1983. One specimen is displayed in the hall case.

Because of the close ancestral relationship between wolves, coyotes, and domestic dogs there is often much overlap in cranial features making positive identification sometimes very difficult. Several times each year specimens collected in Montana are brought in to the university for positive identification. The university's museum has a series of skulls from wolves and domestic breeds, to known wolf/dog hybrids which can be used for comparison. Even with these it is often a difficult determination. In general wolves and dogs can be distinguished from coyotes based upon the relative degree of braincase development. Proportionately the braincase of the coyote is more highly developed and its rostrum is narrower and less massive. Rostral proportions are determined by the relationship between palatal width between the first upper premolars and the length of the upper molariform toothrow, B/A x 100 [refer to Fig. 1 below from Howard (1949). J. Mammal. 30, 169-171]. Dogs and wolves are more difficult to differentiate because the evolutionary distance between these groups is much less. Many domestic breeds such as the Alaskan husky and German shepherd still closely resemble their progenitors. Commonly with domestication has come higher development of the braincase particularly in the frontal region (lljin, 1941). Comparison with wolves can be made by measuring what is termed the orbital angle [Figure 82, Hoffmann and Pattie key]; in domesticated breeds this angle is generally > 50 , in wolves it is less. Additionally with the expanded frontal region the braincase and the rostrum of dogs tend to meet at a sharper angle than is observed in wolves. Most often a detailed series of measurements (refer to Figure A.1 below) must be taken and statistically analyzed using multivariate discriminant procedures before more conclusive identification can be made.

Such analyses as applied to wild canids are discussed in R.K. Wayne (1986), Evolution 40, 243-261. Look at Figures 2 and 3 (appended) from this paper and you will see that the bivariate relationship between face length and skull length is very similar between domestic and wild canids (and thus not a distinguishing characteristic) but that significant differences are found between dogs and wild species when the bivariates, palatal width/skull length, zygomatic width/skull length, and P4 length/skull length are regressed. When multivariate analyses are performed further separation is possible with wolves (1a in Figure 3 appended) being on the periphery of the scatter for domestic dogs. You should attempt to make these measurements on the coyote and wolf specimens in lab and the unknown specimens provided in order to familiarize yourself with this morphologic problem.

Family Felidae:

The Family Felidae is comprised of fewer recent genera, 4, than found in the canidae, though it is currently represented by one more species, 37. The worldwide distribution of felids closely matches that of the canids. Of the 7 species in 3 genera found in North America, 4 species (including the domestic cat) occur in Montana. You should examine the skins and skulls of the following felids:

Felis concolor (mountain lion)

Felis catus (domestic/feral cat)

Lynx rufus (bobcat)

Lynx Iynx (Iynx)

Study the stages of tooth succession as demonstrated by the series of immature Felis concolor. Felids illustrate the evolutionary trend toward reduction in total tooth number and one of the highest degrees of dental specialization. Observe the extreme carnassial nature of this dentition and determine the dental formulae for these 4 species.

Montana is thought to have the largest population of Iynx in the continental United States. Montana is a somewhat unique environment where Iynx are found at their southern most distribution while bobcat are found at nearly their northernmost distribution. The interface between these species is maintained, and the competition that could potentially exist is lessened, by the different physical attributes and habitat requirements of the species. You should look carefully at the physical appearance of both species to see the differences. Interestingly, when these species come into contact with one another it is the bobcat which is the more aggressive, displacing the Iynx

Though the Iynx commonly appears larger than the bobcat because of its longer legs and larger feet, in Montana they are of nearly equal size and the bobcat may indeed be heavier. The well documented reliance of Iynx on snowshoe hares and the resultant population cycling that has been described in every ecology text may not be as tight in Montana as is thought to be further north. Predation studies suggest that Iynx along their southernmost distribution readily shift to feeding upon small rodents in times of snowshoe decline and thus are able to compensate for the loss of this food source.

Mountain lions are common in Montana particularly throughout the western third of the state. Each summer many individuals are trapped within the Missoula city limits and relocated. The population increase which has been noted over the past several years is thought to be the result of an increased deer population, itself a result of several mild winters. Such an increase has been met by an increased legal harvest statewide with over 450 animals taken in 1993.

Biology 306 - MAMMALOGY LABORATORY

Laboratory 4: Order Didelphimorphia - Opossums

The Order Didelphimorphia contains 16 families within which are 71 genera and approximately 258 species. They are found throughout North and South America, Europe, and Australia. In North America north of Mexico only one species exists, the Virginia opossum, Didelphis virginiana. Though this species has been expanding its range to the north and east since the Pliocene it has not even approached Montana on its own. However, in 1943 it was first recorded on the Washington coast, probably as a result of an introduction into the Seattle area. Since this time the population has been expanding steadily eastward entering Idaho by the late 1970's reaching Darby, Montana in the summer of 1989. You should be able to identify this single species:

Family Didelphidae. . . . . . . Didelphis virginiana

Since this species has only recently entered Montana it is not described in Hoffmann and Pattie's mammal key. The following description will be helpful:

Primitive skull 85 to 142 mm long with very small brain case, well-developed sagittal crest, pronounced zygomatic arches, and 50 teeth (refer to figures below); Hind foot with opposable thumb and lacking claw, tail scaly with little hair and prehensile; Females with abdominal pouch. Dental formula: i 5/4, c 1/1, p 3/3, m 4/4 = 50.

The Virginia opossum exhibits all of the characteristics of a typical marsupial. Foremost among these, it has a pouch, marsupium, where young develop after birth. The dentition of this species is quite unique and primitive. A total of 50 teeth are present. The molariform teeth are an excellent example of the primitive tritubercular (tribosphenoid) cusp shape. This species is an omnivore thus the dentition is not highly specialized.

Order Insectivora: Family Soricidae- Shrews (and Moles)

The Order Insectivora is comprised of a variety of diverse mammals from the hedgehogs and tenrecs of Africa, Europe and Asia, and solenodons of Cuba, to the more familiar moles and shrews of North America. At least 20 genera with a total of 265 species are found throughout the world with the exception of the Australian region and the Arctic. In Montana this Order is only represented by 9 species of soricid shrew. Though moles (Family Talpidae) are common throughout the continental United States, and can be found in west-central Idaho, in the extreme south-eastern region of Wyoming, and in eastern North Dakota, there are, as yet, no records of their occurrence within Montana.

The Family Soricidae comprises the "red-toothed" shrews. The 9 species found throughout the state range in size from less than 2 grams, the pygmy shrew (Sorex hoyi) (a penny weighs 3 grams) to approximately 35 grams, the northern water shrew, Sorex palustris. With the exception of the water shrew, which is found in cold, fast- rushing mountain streams of the western portion of the state, the other Montana shrews are semi-fossorial. The pygmy shrew vies with 2 other species (1 in Alaska and 1 in Asia) for the record as the smallest mammal in the world. The soricid shrews are very primitive, retaining many characteristics which placental mammals possessed at the time they diverged from marsupials nearly 60 million years ago. Their developmental pattern reflects relationships to early marsupials (refer to the summary in the hall display case) and they exhibit many anatomical features that are similar to species found in the fossil record of this period such as their tritubercular dentition, lack of a zygomatic arch, and open, ring-shaped auditory bullae (refer to the skull figures below).

Using your lab manual and the illustrations provided below you should be able to identify skulls of the following soricids:

Sorex cinereus (common or masked shrew)

Sorex vagrans (vagrant shrew)

Sorex monticolus (montane shrew)

Sorex palustris (northern water shrew)

Sorex hoyi (pygmy shrew)

You should be able to distinguish between the general body form of most Sorex species found in the state and Sorex palustris. This is a difficult group requiring more detailed taxonomic keys and considerable experience. A very good key for future reference is: Jane Junge and Robert S. Hoffmann (1981), Key to the long-tailed shrews of the U.S. and Canada, Occ. Pap. Mus. Nat. Hist., U. Kansas, No. 94, 1-48.

A Ph.D. student at the University of Montana studied the taxonomy of the Sorex vagrans complex in the early 1970's and came to the conclusion that 2 forms formerly identified as subspecies, S. vagrans vaurans and S. v. monticolus should be recognized as distinct species, thus the current S. vagrans and S. monticolus. [Hennings, D. and R.S. Hoffmann, 1977. A review of the taxonomy of the Sorex vagrans species complex from western North America. Occ. Pap. Mus. Nat. Hist., U. Kansas, No. 68, 1-35.] Similar research recently by van Zyll de Jong in Alberta and Saskatchewan and Foresman in Montana elevated a S. cinereus subspecies to specific rank, the current S. haydeni. Though both species do occur in Montana you will only be required to identify S. cinereus.

Note the skull characteristics mentioned above and the unusual unicuspid teeth which can be found between the highly modified incisors and the premolar.

Order Lagomorpha: Family Ochotonidae (pikas) and Family Leporidae (rabbits and hares)

There are 2 families of lagomorph in North America represented by a total of 17 native species. Of these 17 species 8 are to be found in Montana. This group has been the center of much debate as to its taxonomic relationship with other mammalian groups. At one point it was identified as a suborder of the Order Rodentia; more recently it has been suggested to be more closely allied to the Order Artiodactyla and some individuals still consider them to be closely related to the elephant shrews, Order Insectivora!

Members of the 2 families, Family Ochotonidae (pikas) and Family Leporidae (rabbits and hares) can be readily distinguished on the basis of skull morphology. Separating the 2 genera within the Family Leporidae becomes more difficult especially when this is attempted based upon pelt characteristics.

One characteristic which can immediately be used to distinguish the skulls of lagomorphs and rodents is that the former has 2 upper incisors (rodents have only 1) and the second incisor grows in behind the first. These incisors are ever-growing and the cheek teeth are hypsodont and lack roots.

Lagomorphs are strict herbivores and are highly efficient at retrieving nutrients from ingested plant materials. A high percentage of fecal matter is actually processed twice through the digestive tract: the first pass through leaves many nutrients within the fecal pellets and these are excreted in a moist condition. The animal reingests these pellets (a process called coprophagy) and more nutrients are absorbed.

The common terms "rabbit" and "hare" are often used improperly. Technically the term "hare" refers to members of the genus ____ but the jack"rabbits" (e.g. Lepus townsendii) are actually hares. There are many physiological and behavioral characteristics which distinguish rabbits and hares: rabbits are born naked, blind and helpless (a condition described as altricial) while hares are born with their eyes open, are fully furred and are able to run almost immediately (they are precocial). Rabbits build a nest and line it with fur; hares do not use a nest and give birth in the open. We will look at the following Montana lagomorphs:

Family Ochotonidae

Ochotona princeps - Pika

Family Leporidae

Lepus americanus- Snowshoe hare (skin and skull to species; winter and summer pelts)

Lepus townsendii_- White-tailed jackrabbit (skin to species; skull can only be distinguished as that of a jackrabbit thus it will be either L. townsendii or Lepus californicus)

Lepus californicus- Black-tailed jackrabbit (skin to species; skull as above)

Brachylagus idahoensis- Pygmy rabbit (skin and skull to species)

Sylvilagus nuttalli- Mountain cottontail (skin to genus; skull to species)

Sylvilagus audubonii - Desert cottontail (skin to genus; skull to species)

Sylvilagus floridanus- Eastern cottontail (skin to genus; skull to species)

Biology 306 - MAMMALOGY LABORATORY

Laboratory 5: ORDER CHIROPTERA - Family Vespertilionidae

"The wings of a Batt are wonderful strange, consisting of one intire Skin, webb'd together like the Feet of a Water-Fowl; the Claws or Hooks on the tops of the Wings this Creature makes use of, to hang by to any thing it is minded." Albin, 1740.

The name "chiroptera" is derived from the Greek combination cheir which means "hand" and pteron which means " wing". The Family Vespertilionidae, within which Montana species lie, is comprised of 34 genera and approximately 324 species distributed throughout temperate and tropical forests. Of this number 14 species are to be found in Montana, 8 in the genus Mvotis. We will look at a representative series of these species in lab. Little is known about most of these species in Montana though several are thought to be quite rare.

You should look at museum and skull specimens of the following species:

Eptesicus fuscus (Big brown bat)

Lasionycteris noctivagans (Silver-haired bat)

Lasiurus cinereus (Hoary bat)

Myotis lucifugus (Little brown bat)

Corynorhinus townsendii (Western big-eared bat)

Two additional species are shown in the hall display case, the pallid bat, Antrozous pallidus, and the spotted bat, Euderma maculatum. Though these species are too rare for us to put skulls out, you should be able to identify the museum specimens and know the information presented for both species. In Montana both of these species are considered extremely rare and thus critically imperiled.

Eptesicus fuscus and Myotis lucifugus are yearround residents of Montana and are commonly found throughout the state. Lasiurus cinereus, Lasionycteris noctivagans, and Corynorhinus townsendii are migrants moving into the state in May and returning southward in September. All of these species are heterothermic and may lower their body temperature on a daily basis to conserve energy when they are roosting. Lasiurus and Lasionycteris are primarily tree-roosting species while the others prefer caves, mine shafts or old buildings.

Because of the evolution of flight bats have a unique skeleton. Look at the prepared material and the diagrams below to see primarily the structure of the fore- and hindlimbs, and the pelvic girdle. The forelimb (humerus, ulna, and radius) are held in a position as though you extended you arm outward with the thumb of the hand pointing upward. The digits are elongated to provide the main support for the wing membrane. The thumb is the first digit and supports a well-developed claw from which the bat is able to hang. The pelvic girdle is positioned so that the knees face backwards thus when the hind leg is flexed it bends forward. Many species, such as those in Montana, have a membrane (uropatagium or pterygium) supported by the hindlimbs and the tail vertebrae. By flexing the hind legs this membrane functions like a baseball glove and can be wrapped around an insect in flight.

Bat teeth have become specialized over the course of their evolution. In general there has been a reduction in the number of teeth and those remaining have become very specialized for an insectivorous diet (in F. Vespertilionidae) as is shown below. The reduction in tooth number has accompanied a shortening of the rostrum bringing the remaining teeth closer to the jaw musculature thereby increasing the force which can be exerted through them. There are strong similarities between the teeth of bats and those of shrews (O. Insectivora), both showing characteristics of the very primitive mammals from which these groups evolved, and a clear indication of the relationship between these two groups. Incisor teeth have been reduced in number and are often quite small. Canines retain the primitive condition; long and pointed. Most often the premolars are sharp-edged and function like a short, broad canine. Molar teeth have sharp cusps and ridges with upper and lower teeth opposing one another producing cutting surfaces. Each upper molar has 4 cusps (2 lateral and 2 medial); outer cusps have 2 sharp ridges which extend to the outer edges of the tooth. The 4 ridges together form a W-shaped pattern which is quite distinctive. The exact evolution of each tooth in the various species we will look at is not easy to discern and may vary greatly between species.

The remarkable ears and nose structures exhibited by many species (e.g.- the western big-eared bat, Corynorhinus townsendii below) have evolved in conjunction with the use of echolocation. We will spend several lectures discussing the use of ultrasound for foraging and object avoidance.

Look at the equipment (mist nets and harp trap) used for the collection of bats; discussion of the use of this equipment can be found in Techniques Paper #3.

Biology 306 - MAMMALOGY LABORATORY

Laboratory 6: ORDER ARTIODACTYLA - Family Cervidae, Family Suidae, Family Dicotylidae

The even-toed ungulates comprise a diverse group of 79 genera and 192 species within which are to be found the pigs and peccaries, hippopotamuses, camels, deer, giraffes, pronghorn, cattle, goats and sheep. We will look at this diverse group over two laboratory periods. In Laboratory 6 we will consider three families, the cervids, suids, and dicotylids. In Laboratory 7 we will turn our attention to the Family Bovidae (particularly goats, sheep, and bison) and the Family Antilocapridae (pronghorn).

Family Suidae and Family Dicotylidae: Pigs and peccaries There are no suids or dicotylids native to Montana though these are very interesting groups with unique dentition. There are single species for each of these families represented in North America.

Family Suidae

Sus scrofa - Domestic (and feral) pig

This species possesses 44 teeth (i 3/3, c 1/1, p 4/4, m 3/3 = 44) and is the only artiodactyl with this number. The presence of upper incisors separates this species from many of the other artiodactyls which you will study. The occipital crest is quite unique, sweeping upward and backward and the canine teeth are large and recurved. Pigs were brought to North America in the 1600's and 1700's for food. Many escaped or were released; feral animals have become a significant problem in many regions of the country, particularly the southeast and southwest. In Great Smoky National Park they are destroying so much of the habitat that there are concerted efforts to exterminate them. They use their tusks to rototill the ground looking for roots and bulbs and in the process seriously disrupt the habitat.

Family Dicotylidae

Tayassu tajacu - Collared peccary

The dental formula for this species is i2/3, c1/1, p 3/3, m 3/3 = 38. Here the presence of 2 rather than 3 upper incisors is diagnostic. This species is native to the southwestern United States extending southward to Argentina. The pelt is much coarser than that found in suids with very stout bristles. Both suids and dicotylids have 2-chambered stomachs rather than the 4-chambered ruminant stomach common to cervids.

Family Cervidae

Odocoileus virginianus - White-tailed deer

Odocoileus hemionus - Mule deer

Alces alces - Moose

Cervus elaphus - Elk

Rangifer tarandus - Caribou (reindeer is the European term for the exact same species)

The above 5 species of cervid are native to Montana. Using Hoffmann & Pattie you should be able to easily identify each of these. You should become familiar with skulls of both males and females. With the exception of caribou only males possess antlers. Since the caribou is rare and quite limited in Montana we have only a few specimens in our museum collection. The distinguishing characteristic for caribou is the small size of their incisiform teeth. A lower jaw of this species has been placed in the hall display case for you to see. If you have a male and antlers are present species can be readily identified from antler morphology. However, even males shed their antlers so it is important to learn other distinguishing characteristics for these individuals as well as for females.

Skins for these species will also be placed out in the lab. Pay particular attention to such body characteristics as tail shape and color, and the size and color of the tarsal and metatarsal glands in the genus Odocoileus. One hybrid O. virginianus x O. hemionus skin is available from a female.

Aging "boards" for elk and deer are available in the lab just for your interest. Look at these to see the typical wear patterns seen in these species. Keep in mind that such wear is highly variable, influenced by the quality and abrasiveness of the foods being eaten. The timing of tooth replacement is also dependent upon food abundance and quality.

Review your information on tooth structure for these groups (heterodont, brachyodont, selenodont).

Biology 306 - MAMMALOGY LABORATORY

Family Bovidae- (goats, sheep, bison, muskox)

There are 45 genera with approximately 128 species distributed across North America, Africa, and Eurasia. As with other artiodactyls, these animals possess 2 prominent digits (#'s 3 & 4), digits 2 and 5 are either absent or greatly reduced as dew claws. All species have 4-chambered ruminant stomachs. This family (as well as the Family Antilocapridae) is distinguished by the presence of horns rather than antlers as found in the Family Cervidae. All males, and females in most genera (all species native to Montana), have horns though those grown by females are often smaller or less elaborate.

There are 3 wild species native to Montana. We will study these as well as 3 additional species as follows:

Bison bison- Bison (skull)

Bos taurus- Domestic cow (skull)

Oreamnos americanus- Mountain goat (skulls of males and females; pelt)

Ovis canadensis- Bighorn sheep (skulls of males and females; pelt)

Ovis dalli- Dall sheep (not found in Montana) (skulls of males and females; pelt)

Ovibos moschatus- Muskox (not found in Montana) (skull of male)

Since the Dall sheep and muskox are not native to Montana your laboratory key does not have any information on these species. Use the following information from Hall (1981) for their identification:

To distinguish the sheep:

Nasals in males usually larger than 105 mm, in females usually longer than 85 mm; horns in males more massive, heavier in general appearance, and more tightly curving toward the face(note); .. . . . . .Ovis canadensis

Nasals in males usually shorter than 105 mm, in females usually shorter than 85 mm; horns in males less massive, finer in general appearance, and spiraling outward away from the face . . . . . .Ovis dalli

(note) female horns are less distinct between the species and are much smaller than those of males and only slightly curved;

To distinguish muskox from bison:

Horns smooth, conical; paraoccipital processes widely separated from condyles; .. . . . . . . . . . . . . . . . .Bison bison

Horns rugose, flattened at base; paraoccipital processes not widely separated from condyles . . . . . . . Ovibos moschatus

Note: Figures 104 a and b, page 64 in Hoffmann and Pattie are reversed. Fig. a depicts a cow skull and Fig. b depicts a bison skull.

You should look at the skulls and pelts placed in lab. For the sheep and goats you should attempt to age the animals by the annular growth rings on the horns (refer to hall display case for diagrams on horn aging in the goats).

Family Antilocapridae - (prong horn)

The pronghorn, Antilocapra americana, is a monotypic species endemic to North America. It possesses many unique anatomical and physiological characteristics that has made a study of its taxonomic relationship to other artiodactyls difficult. Both sexes grow horns though those of the male are much larger. Horn sheaths are forked (pronged) and flattened around a flattened bony core. They are deciduous and the sheath (an epidermal derivative homologous to the velvet of cervids) is shed annually. Look at the horn display which illustrates growth of these structures.

Notice the brittle nature of the guard hairs, similar in character to those of the sheep, and the unique coloration pattern. The black subauricular patch, only found in males, hides glands that become active as the animal enters the breeding season.

Both bovids and antilocaprids possess hypsodont molariform teeth and a selenodont cusp pattern.

Biology 306 - MAMMALOGY LABORATORY

Laboratory 8: Order Rodentia - Family Sciuridae

The Order Rodentia contains the largest number of species of any mammalian order; approximately 1,687 species are recognized within 380 genera of 29 families. With such a large and diverse group of species it is not surprising that members of this order are distributed worldwide inhabiting a wide diversity of habitats. Many attempts have been made to understand the taxonomic relationships between this highly diverse mammalian group. One of the more widely accepted proposals is outlined below:

Current taxonomic status of North American rodents: [after Carleton, M.D. (1984) Introduction to rodents. In: Orders and Families of Recent Mammals of the World (S. Anderson and J.K. Jones, Jr., eds.) Wiley, New York]

O. Rodentia

Suborder Sciurognathi

Family Aplodontidae - mountain beavers

F. Sciuridae - squirrel (ground, tree, flying), mammots, chipmunks

F. Castoridae - beavers

F. Geomyidae - pocket gophers

F. Heteromyidae - kangaroo rats, pocket mice

F. Dipodidae - jumping mice (some authors still place these in the F. Zapodidae)

F. Muridae - now includes the F. Cricetidae which has been encompassed by the subfamily Sigmodontinae; Old World rats and mice, voles, lemmings

Suborder Hystricognathi

F. Erethizontidae - New World porcupines

F. Myocastoridae- nutria

Historically the terms sciuromorph, myomorph and hystricomorph have been used to identify major taxonomic divisions within the Order Rodentia. At one point these terms even applied to Suborders within this Order. The terms themselves describe three general patterns in the arrangement of the masseter muscles (those primarily involved in jaw closure) to the skull and zygomatic arch. Not every rodent species can be easily placed into one of these three groups, but the concept is still useful as a general means of categorizing many species.

Figures 16-1, 16-2, 16-3, 16-4, 16-5 and 16-25 in Vaughan (3rd edition) will be helpful in understanding these differences

Characteristics:

1. Sciuromorphous - [Suborder Sciurognathi:F. Sciuridae and F. Castoridae]

a. infraorbital foremen is relatively small and slit-like and the masseter muscles do not pass through it

b. The masseter lateralis is shifted anteriorally to insert on the zygomatic arch along its anterior border with its origin on the rostrum

c. The angular process of the dentary is roughly in the same plane as the rest of the dentary

2. Myomophous - [Suborder Sciurognathi:F. Muridae and selected other species]

a. the infraorbital foremen is slightly enlarged but still somewhat slitlike; medial masseter muscle originates on the rostrum and passes through these foramina

b. the angular process of the dentary does not flare out

3. Hystricomorphous - [Suborder Sciurognathi:F. Dipodidae; Suborder Hystricognathi: F. Erethizontidae, F. Myocastoridae]

a. the zygomatic arch is quite large

b. the infraorbital foremen is enlarged and mostly rounded and the masseter medialis passes through it to originate on an extensive area of the rostrum

c. in many species the angular process of the dentary flares out

4. Protrogomorphous - [Suborder Sciurognathi:F. Aplodontidae] Most primitive condition from which all other forms are thought to have originated. The masseter muscles originate entirely on the zygomatic arch. Aplodontia is generally regarded as the most primitive living rodent.

The most recently accepted Suborder designations Sciurognathi and Hystricognathi now apply to differences in the structure of the mandibles. Sciurognathous types possess an angular process of the dentary bone which originates in the vertical plane that passes through the alveolus of the incisor and is ventral to the alveolus. In the hystricoanathous form the angular process originates lateral to the vertical plane of the alveolus. Compare the dentary of Castoridae (sciurognathous) to that of Erethizontidae (hystricognathous).

Forty five species are recognized in Montana, placed within 7 families. In the first of three labs devoted to this group we will be studying members of the Family Sciuridae, the group containing the tree and ground squirrels. Keep in mind that, as we study this order, you will be allowed to use any notes you find helpful as well as your laboratory guide on the iast laboratory practical exam. You will be asked to simply identify specimens (there will be no questions on habitat associations, characteristics used to identify individuals, etc.). Thus the strategy is to become familiar with key characteristics so that you can work through the key in a timely fashion. On this exam you will be asked to identify two specimens which you have never seen before (and which do not occur in Montana) using a dichotomous key which you have as well not seen before. In other words, you need to become familiar with skull characteristics representative of this group so that you can apply this information using any key that might be available for members of this group.

Suborder Sciurognathi

Family Sciuridae

Marmota flaviventris (a) yellow-bellied marmot

Marmota caligata (a) hoary marmot

Marmota vancouverensis Vancouver marmot (hall display case)

Marmota olympus Olympic marmot ( " )

Marmota broweri Alaska marmot ( " )

Tamias minimus (b) least chipmunk

Tamias amoneus (b) yellow-pine chipmunk

Tamias ruficaudus (b) red-tailed chipmunk

Cynomys ludovicianus (a) black-tailed prairie dog

Cynomys leucurus (a) white-tailed prairie dog

Spermophilus lateralis (a) golden-mantled ground squirrel

Spemmophilus tridecemlineatus (a) thirteen-lined ground squirrel

Spermophilus columbianus (a) Columbian ground squirrel

Glaucomys sabrinus (a) northern flying squirrel

Tamiasciurus hudsonicus (a) red squirrel, pine squirrel

Sciurus niger (a) fox squirrel

(a) You are responsible for identifying these species to the species level from both skins and skulls; (b) You are responsible for identifying these species to species based upon their skins, but only to genus by skull;

Several additional species (S. richardsoni, S. ammatus, Tamias umbrinus) are common in the state but are very difficult to identify. You are not responsible for these species.

Biology 306 - MAMMALOGY LABORATORY

- Families Aplodontidae, Castoridae, Heteromyidae, Geomyidae, Dipodidae, and Muridae

We will continue our look at this large mammalian order. Of the groups listed below, one, Family Aplodontidae, is not represented in Montana. We will however look at the single species within this Family because of its unique place in the classification of this order.

You should study the following species: (all should be identified by pelt and skull)

O. Rodentia Suborder Sciurognathi

Family Aplodontidae - (mountain beaver)

Aplodontia rufa

F. Castoridae- (beaver)

Castor canadensis

F. Geomyidae - (pocket gophers)

Thymomys talpoides - Northern pocket gopher

F. Heteromyidae - (kangaroo rats, pocket mice)

Dipodomys ordii - Ord's kangaroo rat

Perognathus parvus - Great Basin pocket mouse

F. Dipodidae - jumping mice (some authors still place these in the F. Zapodidae)

Zapus princeps - Westem jumping mouse

F. Muridae - now includes the F. Cricetidae which has been encompassed by the subfamily Sigmodontinae; Old World rats and mice, voles, lemmings

Rattus novegicus - Norway rat (brown rat)

Mus musculus - house mouse

Subfamily Sigmodontinae (Cricetinae)

Neotoma cinerea - bushy-tailed woodrat

Reithrodontomys megalotis - Westem harvest mouse

Peromyscus leucopus - white-footed mouse

Peromyscus maniculatus - deer mouse

Biology 306 - MAMMALOGY LABORATORY

Laboratory 10: Order Rodentia - Families Muridae (contd.), and Erethizontidae

The last lab will be devoted to the final group of rodents found in Montana. The murids in particular are a difficult group requiring a detailed knowledge of tooth cusp patterns. Mastery of this information proves very useful not only in identifying a majority of the small mammals present in the state but also in being able to identify food items for raptors. Prey base studies for owls requires dissection of owl pellets and an analysis of tooth and jaw fragments. The only way to identify these rodents to species is by being able to identify isolated teeth.

O. Rodentia

Suborder Sciurognathi

F. Muridae - now includes the F. Cricetidae which has been encompassed by the subfamily Sigmodontinae; Old World rats and mice, voles, lemmings

Subfamily Arvicolinae (Microtinae)

Synaptomvs borealis - Northern bog lemming

L. curtatus - sagebrush vole

Clethrionomys gapperi - red-backed vole

Phenacomys intermedius - ~ heather vole

Microtus ochrogaster - prairie vole

Microtus richardsoni - water vole

Microtus longicaudus - long-tailed vole

Microtus pennsylvanicus - meadow vole

Microtus montanus - montane vole

Ondatra zibethicus - muskrat

Suborder Hystricognathi

F. Erethizontidae - New World porcupines

Erethizon dorsatum - porcupine