Ranging from Honduras across South America to Argentina, sloths are another of nature’s strange mammals. There are two families containing a single genus each: three-toed sloths, Bradypus, and two-toed sloths, Choloepus.
Unique characteristics of sloths include toe attachment and three recurved claws on each forelimb which allow them the habit of hanging upside down from all limbs, awake or sleeping. Their hair is different from other mammals in two ways: first, hairs have very tiny grooves which allow for attachment and growth of blue-green algae. Algae give sloths a greenish hue to their fur, which provides a camouflage while hanging upside down high in the trees. Secondly, hair patterns flow from the central stomach area to the back, allowing rain to shed off the belly while hanging upside down. They have a low center of gravity, contributing to very slow and deliberate movements. Adults weigh from five to 15 pounds and are mostly brown in coloration and are 12 to 20 inches in length.
Sloths are arboreal, meaning that they live in trees and are active during the day and night. They have a low metabolic rate and low body core temperatures. This is probably due to their diet of leaves which digest slowly and have rather low content of nutrients. Stomachs of sloths are divided into compartments. Leaves ferment in these compartments and in the small intestine where bacteria decompose leaves and perforate cellulose cell walls. Although sloths spend the majority of their lives in trees, they descend to the earth several times a week to eliminate body wastes. Sloths tolerate humans and are often found as residents of parks and other places near human populations. I remember seeing a sloth in a tree near a bus stop in Brazil. The most notable thing about it was its upside down demeanor and very slow movements.
Sloths may harbor arthropod-borne viruses, such as yellow fever, St. Louis encephalitis, ilheus virus and Venzuelan encephalitis. These may circulate in their bloodstream for long periods of time, allowing transmission of disease to mosquitoes to humans or other animals. In Panama, two-toed sloths host causative organisms of leishmaniasis in humans.
A single young sloth is born after a gestation period of about six months. It remains dependent upon its mother for food for approximately four weeks and is carried around on the mother’s back. The young remains with her about six months. Since sloths depend on leaves as food, they are found where most trees keep their leaves throughout the year. Their home range is about three to four acres. Sloths maintain desired body temperatures by moving in and out of the sun. They are prey to Harpy Eagles, the largest birds of prey in the Amazon rain forest, but otherwise have a very low mortality rate as evidenced by their low reproductivity.
Lord, R.D. 2007. Mammals of South America. The John Hopkins University Press, Baltimore. 198 p.
Redford, K.H. and J. F. Eisenberg. 1992. Mammals of the Neotropics: The Southern Cone. Vol. 2. The University of Chicago Press, Chicago and London.
Becoming an expert tracker requires close attention as it often is a rather complex process. Some basics were mentioned in the former Part I tracking article, but there are still a number of additional items to consider. Again, Lord Baden-Powell’s (BP), the father of modern Boy Scouting, writings will be referenced.* He was incredibly expert in many facets of outdoor campcraft skills.
English “tracking” is called “spooring” and in India it is called “pugging.” In days before modern transportation, when most rural travel was by horseback, tracking was much more pertinent to one’s daily life than currently. Nowadays, not many of us are impacted by stolen livestock or criminals making their getaway on foot or on horseback. War scouts rarely need to rely on tracking due to all the modern technologies under their command. Hunters, however, still find tracking useful as they carefully observe sign or “spoor” to eventually encounter their quarry.
In tracking humans (barefoot), measure the footprint of the target person, draw a line from the tip of the big toe to the tip of the little toe, then key on where the other toes come in regards to this line and record it in your field notebook. In my own family, I have noted that several of us have toes with different ratios to the big toe, making each one’s footprint rather unique. When you encounter a confluence of footprints, it only takes a few measurements to identify the one you are following.
To ascertain the pace of tracks being made, remember that a walking person puts the entire flat of the foot on the ground, with strides a little under 36 inches. A running person digs his toes more deeply into the ground as dirt is kicked up—strides more than 36 inches apart. A backwards walking person can be known as the strides are shorter, the toes more turned in, the heel marks dug deeper. Fast moving animals dig their toes more deeply into the dirt and their paces become longer, kicking up more dirt. When walking, a horse makes two pairs of prints. At a trot, the track is similar, but the stride is a little longer. Hind feet are often longer and narrower in female horses. The state of the soil or ground (mud, sand) and weather (snowing, raining, stiff winds) can greatly affect the value of the “spoor” over even a few minutes or few hours.
In some cases, age of tracks becomes quite important. If I am hunting mule deer and see an older track, I will likely look for another more recent track—I generally have little or no interest in a track made several days ago. I would much rather find a fresh track to follow with the possibility of a large deer jumping out in front of me than an old track where there is very little possibility of surprising its maker. Sharp edges of a newly made track in the sand become rounded the longer breezes turn the outlying edges to dry dust. In damp ground and under trees, tracks will appear much crisper and fresher as the sun likely will have only partially dried up the edges of the print. Prints with small cavities made by rain drops will have been made prior to recent rainfall. Older prints made in the snow may be partially obliterated by drifting or melting.
If you are following really fresh tracks, you must avoid following too closely, as the pursued animal will frequently look back to see if it is being followed. In such cases, the tracker makes a circle and comes back to where he would expect to see the tracks again. If he finds it, he continues to make circles until he finds no tracks. Now he knows he is ahead of his quarry, so he gradually circles nearer and nearer until he finds it, taking care not to get upwind of the animal within scenting distance. If tracking over hard ground or in grass, where sign is difficult to see, remember the direction of the last print and look in the same direction 30 or so yards in advance. Careful observations may show small displaced stones or soil scratchings or blades of bent grass in a line, one in advance of the other, giving the tracker the general overall direction of travel.
Expert tracking is fast becoming a lost art, especially among non-hunters. Likewise being less common is the art of astute observation. Practice the latter in the city, at home, or wherever you are and your skill and interest in tracking will greatly increase!
*Scouting for Boys–A Handbook for Instruction in Good Citizenship Through Woodcraft. Lord Baden-Powell of Gilwell, World Brotherhood Edition. Copyright 1946 by the (British) Boy Scouts Association. Published by Boy Scouts of America.
How well do you observe things around you? Do you remember the kind of car that just passed, the color of shoes of the lady who waited on you at the restaurant where you dined an hour ago, or how many stories high was the apartment building on the left side of the street two bocks past? As you walk through the woods, what is the significance of the black and white feather in the path, the earth alongside that looks like it was plowed up, or the huge cat-like footprints in the path? Each “sign” has special significance to the cautious nature observer and/or “tracker.”
In his book, Scouting for Boys*, Baden-Powell (BP), the father of modern Boy Scouts, teaches about “observing”—its importance in tracking wildlife. This present article will incorporate some of his expertise on the subject.
If you are tracking wild game, one has to be especially observant. Small, obscure items such as a broken twig, tramped grass, footprints, a hair, drop of blood, scratch marks on a tree—all have special meaning to a seasoned tracker. BP emphasized the importance of not allowing a single sign to escape one’s attention. First, the sign must be noticed, then, secondly, the meaning must be discerned. All four of our senses need to be constantly alert—sight, hearing, smell, touch –in being prepared to make observations. However, sight and hearing are most often used during the daytime.
Scientists carry a field notebook when engaged in field research. This can be a small notebook (waterproof paper is good) or binder and writing utensil with permanent ink. It is wise for the tracker or observer to also have a similar method of recording observations at hand. Memories often play tricks with the mind. Be sure to write down date, exact time and wheeabouts, number pages, note weather conditions (at the top of the page), then record observations.
Practice is important in learning how to be a good tracker. Most of us aren’t normally inclined to be good observers, so special attention needs to be paid to practicing. One’s eyes need to be continually moving in every direction, near and far, noticing everything that is going on. This can be done anywhere, even in city and town, especially noticing people—their faces, their dress, their boots/shoes, their way of walking. Try and make out from their appearance whether they are rich or poor, what is their probable business, whether they are happy or ill. Care should be taken so as not to be too obvious in observing. Also, keep your eyes on the ground. I have found trinkets and coins and tools by observing the ground while walking, even though many others had already passed over the same ground. A fun game is to quiz one another about recent observable peculiarities of persons recently encountered, architectural qualities of buildings, store window displays, or interesting and unusual actions of city animals or humans.
BP tells the Sherlock Holmes experience of meeting a stranger and noticing that he was looking fairly well-to-do, in new clothes with a mourning band on his sleeve, with a soldierly bearing, a sailor’s way of walking, sunburnt, with tattoo marks on his hand. Holmes guessed, correctly, that the man had recently retired from the Royal Marines as a Sergeant, that his wife had died, and that he had some small children at home.
It may happen as you are traipsing through the woods some day, that you find the remains of a forest animal or even a dead person. In the latter event, authorities should of course be notified immediately. However, sometimes important sign may be lost before authorities arrive, such as falling or melting snow or severe rainstorms. In such a case, even the smallest sign should be noted and recorded—a small and inexpensive camera is invaluable in this instance. Indeed, one may take 20 to 30 minutes just standing still, photographing and writing thoroughly every conceivable detail when encountering a dead human body: position of hands, feet, lay of body, any unusual marks or wounds on head, face or arms, evidence of a struggle, footprints (measure, sketch/photograph),broken or tramped vegetation/shrubs/trees, blood and its location, etc. Record or sketch the exact original position of the body on a map. Carefully examine the ground around the body without treading on it any more than is necessary by spoiling existing tracks. Record every possible detail surrounding the scene. In natural settings, take note of landmarks or other objects that will prevent getting lost such as distant mountains/hills, church towers, rocky formations, trees, gates, etc. If you need at some future time to exactly describe your way, directions would need to be given unmistakenly and in proper sequence. Every by-road and foot path needs to be noticed and remembered, perhaps recorded. Any information so gathered should be offered to authorities for review.
BP suggests that smaller signs including nearby birds taking hurried flight or rising dust may be indicative of some other nearby person or animal. Tracks of smaller animals, birds, wheels can be suggestive of valuable information.
At night, small details become vital. Listening is chief among senses employed, sometimes by feeling and smelling. During night stillness, sounds carry further than during the daytime. The human voice carries for a great distance, even speaking low. Putting you ear to the ground or placing it against a stick, one can hear the shake of horses’ hoofs or the thud of a man’s footfall from a long distance off.
The keys to effective sign observations and tracking are: practice, practice, and more practice—then, be sure to record details in your field notebook or if you are very good, memorize!
*Scouting for Boys, A Handbook for Instruction in Good Citizenship Through Woodcraft. Lord Baden-Powell of Gilwell, World Brotherhood Edition. 314 pp. Copyright 1946 by the (British) Boy Scouts Association. Published by Boy Scouts of America.
Lord Baden-Powell, the founder of scouting in England in 1907, wrote a book called Scouting for Boys.* The book was based on his outdoor boyhood experiences and later in the Army in India, Africa and Canada. Baden-Powell wrote “I knew every true red-blooded boy is keen for adventure and open-air life, and so I wrote this book to show you how it could be done.”
Most wildlife are very shy and reclusive in their behavior. They have learned over time that their most dangerous predators/enemies are often humans. So, since wildlife rarely wins in a direct confrontation with man, avoidance is the best means of defense and survival. Animal species each have their own “avoidance mechanisms.” Some have several. For example, coyotes and foxes and elk have acute senses of smell. Others, like deer, have highly developed senses of hearing. A misstep on a dry twig may serve as a red flag warning and results in the stalked animal fleeing rapidly away. Some animals have highly developed visual acuity such as owls and hawks and eagles.
Stalking, then, involves creeping up on wild animals without them smelling or hearing or seeing you. It requires considerable skill and patience to observe animals in their native habitats. This ability is necessary, not only for hunters, but also to those who like to photograph and even just observe wildlife.
Some of Baden-Powell’s* teachings on stalking follow:
War scouts and hunters who stalk game always carry out two important things when they don’t want to be seen: 1) They make sure that their clothing is the same color as the background where they are pursuing wildlife; and 2), They use wisdom and good sense to remain completely still without moving. An example of the latter is an experience I had a couple of months ago while hunting for buck mule deer. As I was cautiously and quietly making my way through the woods, I suddenly came upon several female mule deer (does) within about 50 feet. Although I was in plain sight, I froze. The does at first were very alert looking suspiciously in my direction—however, after a few minutes, since I was downwind and perfectly immobile, they resumed feeding. It was only when I consciously began walking in their direction that they bounded away.
In regards to clothing, consider color. If you are dressed in light colored khaki, stay away from white or dark backgrounds. If you remain perfectly still while in khaki-colored sand or grass or rocks, it will be very difficult to see you, even from short distances. If you are dressed in dark clothes, stay among dark bushes, in shadows of trees or rocks. If you are in a lookout situation, such as on a skyline, be very careful not to show yourself as a silhouette against the sky.
Slow Motion—At night, stay as much as you can in low ground—ditches, creek beds, ravines, etc. One advantage of this strategy is that if an enemy comes near you, you will be able to see him first–outlined against the stars. Of course, dark clothing is usually best for night reconnoitering or stalking.
Silent Walking—Another key point in keeping hidden while moving, especially at nighttime, is to walk quietly. Walk on the balls of your feet, not the heels. It may take everyday practice to subconsciously learn to do his, as most people walk on their heels in a heavy-footed manner. You will find that your endurance over long distances will grow as you learn to walk in this manner. Recent snow or rain dampens the terrain and makes moving about noiselessly much less of a challenge. Walking on wet leaves is surely less audible than walking on dry leaves. The same goes for small branches and dry shrubs, as moisture makes them more flexible and less likely to snap or crackle.
Keep Down-Wind—Always sample for wind direction, even if it is so slight as to make leaves barely tremble. Always work against the wind. Wind direction can be sampled by licking a finger and holding it up to see which side feels the coldest. Throwing some dust or dry grass or leaves in the air and watching which way they drift is another effective method.
Disguises—Especially during scouting games and even during actual enemy situations, disguises may become useful. Baden-Powell tells about Indian scouts wearing wolf skins in prowling around enemy camps, mimicking wolf howls. They sometimes wore wolfskin heads when there was possibility of being seen against a skyline. In Australia, natives stalk emus (ostrich-like birds) by putting emu skin over themselves and walking with body bent and one hand held up to mimic the bird’s head and neck. Scouts may tie a string or band around their heads and stick grass or small branches, through it, some upright and some drooping, camaflaging their faces. When hiding behind a big stone or mound, look around the side of it, not over the top.
Stalking is a learned skill. Practice sneaking up and photographing small animals. The quality of your photographs will be an indicator of how far your stalking skill has progressed.
*Scouting for Boys by Lord Baden-Powell of Gilwell, World Brotherhood Edition, Copyright 1946 by the (British) Boy Scout Association
Declining attendance at national parks, lessened interest in college laboratory classes and field trips, and a general malaise about nature, especially among young people, seem to indicate movement away from the natural world.
Dr. Peter Weigl, a prominent biologist, weighed in on the question of apparent national declining interest in nature*.
Home is where it should all begin. Experiences with the out of doors is important in early childhood education. How many parents encourage (or require) their children to mow the lawn, trim hedges, shovel snow or weed the garden? How many families enjoy local hiking where all can observe the changing seasons, identify plant life, keep a check list of birds identified, or look for wild animals in native habitats? How many vacations are taken to national parks or national monuments where nature is unavoidably the focus of attention?
As a parent, I have personally noticed in the raising of our own eight offspring, that most children, especially at early ages, willingly and enthusiastically follow their parent’s lead. When I would get out the canoe to explore an unfamiliar pond, or fish for trout in the nearby creek, or pick fresh peas or raspberries in the garden, almost always no invitation was needed for our children to query, “can we come too”–even before being invited.
Behavioral scientists have indicated that childhood experiences without exposure to the natural world markedly influence later life preferences and educational choices. This affects physical and mental health as well as learning capabilities.
Dr. Weigl suggests three major processes as critical to developing minds: First, is for “time and opportunity for unstructured, unforced exploration of surroundings.” These would be times to touch, play, observe and wonder about what is being experienced outdoors—a learning from within. Second, learning from the example of caring and enthusiastic relatives, teachers, mentors and peers. Fewer of the latter seem to be available these days. Third, is information transfer from reading, personal experiences, teaching, and from an array of electronic sources. This requires sufficient time for personal contemplation, meditation, thought and synthesis. Often in our lives, we tend to “overbook” our own abilities; that is, we jam too many things into too little time. This defeats the premise of allowing ourselves time to think, to sort newly gained knowledge out, and to make connections between observations and value systems. All of these three can be critical to gaining an appreciation for nature–especially early in life.
Our society and culture has changed dramatically from what perhaps we ourselves experienced while growing up. One modern parental concern is the possibility of kidnapping as children solitarily enjoy their surroundings, though the statistical chance of this occurring is exceedingly small. In my own small town childhood, I can remember many times in receiving permission to “go fishing” only to return at the end of the day from experiencing many kinds of outdoor adventures (but usually with no fish); my mother usually had little idea which direction I had gone.
Parents also often seem to have preconceived pathways and lifestyle norms for their children that include mastering verbal, athletic, artistic skills or other avenues of endeavor. Recreation is often squeezed into indoor activities such as computer video games and watching TV and movies, with little or no opportunity to roam in the out of doors. Absence of significant teachers, mentors, relatives or peers who provide guidance in natural surroundings is quite likely in the lives of children. Our educational system has changed dramatically with unfortunate changes in curriculum and additional pressures and paperwork placed on teachers, hampering their efforts. Very often, both parents work and mistakenly have the opinion that “Quality” time adequately replaces “Quantity” time in the lives of their offspring.
Much could be said about the impact of sedentary activities such as electronics in the lives of children. The constant stimulation arising from the Web or video games translates into “boring” visitations to zoos or wildlife refuges. Many joggers wear iPods and are oblivious to natural surroundings. More children are obese than ever before and sedentary lifestyle contributes to this malaise. Healthy and nutritional foods are often replaced by sweets and “fast foods” and children have little or no understanding or taste for “veggies” and fresh fruits leading to healthy eating habits.
It is my own personal hope that entire families–and it must be family-based–will once again find time to go on hikes together, regularly take a walk through nature, begin to plan well in advance for vacation visits to one of the wealth of national parks available in this country. At least once a week, families should make a concentrated effort to be together, not only to enjoy nature, but also to solidify family relationships. Even daily eating a balanced sit down meal together is a worthy family goal. The general decline of the American family should be of the greatest concern to all of us. Future government, industry and education leaders will most likely lead in directions dependent upon childhood and family experiences.
To you kids, get out of doors! To you parents, lead the way together!
*Weigl, Peter. 2009. The natural history conundrum revisited: mammalogy begins at home. J. Mammalogy, 90(2):265-269.
They are sometimes called the “gray ghosts of the mountains.” Not a typical looking chipmunk (with white stripes along the length of their bodies to the head), cliff chipmunks have dark stripes extending from tail to the neck area, then with typical white stripes on the head. This elusive critter is somewhat secretive and fairly difficult to observe. It is quite likely you have never seen one in the wild. But, yes, these chipmunks do live in and among massive rock formations and cliffs in the Western U.S. Their tiny claws allow them to grasp minute irregularities in the surfaces of vertical cliffs which facilitates adroit climbing up and over perpendicular rock masses. They emit several kinds of vocal sounds: One is a “bock” sound, another is a high pitched chirp.
Cliff chipmunks are seed hoarders—they do not hibernate but remain intermittently awake during long wintertimes in their dens within cliff rock cavities. They “hoard” seeds during the summers, often placing newly gathered mature seeds in their internal cheek pouches, carrying them to small caches excavated in soil. Later in the summer or fall, they return and retrieve these seed caches, transporting them to their dens. During cold winters, they curl up and sleep much of the time, awakening every day or two to consume some stockpiled seeds. Such “hoarding” of seeds allows cliff chipmunks to survive during cold mountain winters lasting from November through February into March. New green food plants are generally not available until late April or May. As the snow begins to mostly melt in March, chipmunks search for seeds, new plant growth and other food items among last summer’s accumulation of leaves, rocks and other detritus in the hillsides above and below the cliffs.
One Study* observed various cliff chipmunks collecting seeds from over 30 different plants during a single summer. Of special interest was the ability of chipmunks to feed upon certain preferred, edible kinds of plants as these mature during the summer–stems, leaves and seeds until depleted. Then, they would move on to do the same with food parts of another kind of later maturing plant. It appeared that chipmunks feed freely on various plant parts, stems, leaves, blossoms, seeds, but the latter appears unique as quality high energy suitable for hoarding and storage. A variety of different food plants occurred randomly in the slopes above and below the rocky escarpments which the chipmunks visited depending upon availability and preference.
An actual strategy of how chipmunks feed are as follows: on tender leaf buds of Bigtooth maple (Acer grandidentatum) in May. Trees nearest the cliffs were foraged upon first. It was not uncommon for several animals to feed simultaneously in the same tree at the same time. Towards the end of May, serviceberry (Amelanchier utahensis) buds were the food of choice with berries eaten later in the summer. In June, chipmunks were found feeding upon Arrowleafed balsamroot (Balsamorhiza sagittata) leaves, stems, and seed heads. Typically, the stem was cut and seeds eaten, leaving a tell-tale pile of seed hulls. This plant was fairly widespread over the entire study area. In June, bluegrass seeds (Poa spp.) and wild carrot stem and seeds (Lomatum disectum) were utilized. Salsify (Tragopogon dubius) matured in late June and July. Seed heads and leaves were preferred. In late June and July, bitterbrush (Purshia tridentata) matured and was eaten for the rest of the summer in a number of locations. Bitterbrush seeds appeared to be a major contributor to the winter seed stockpile. Elk thistle (Cirsium spp.) matured in late July. The prickly parts did not seem to deter chipmunks from consuming seed heads. This plant grew singly and was not numerous either above or below the cliffs.
Various plants utilized for food are scattered throughout the area. These are utilized as they become viable food sources for chipmunks and other wildlife.
Hart, E. B. 1971. Food preferences of the cliff chipmunk, Eutamias dorsalis, in northern Utah. Great Basin Naturalist, Vol 31(3): 182-188.
About Cliff Chipmunks, Tamias dorsalis:
Mature cliff chipmunks are typically the size of a small rat. Their mannerisms are similar to other chipmunks of the genus. They normally produce one litter per year (4-6 young) in the northern parts of their distribution. Gestation is from 28 to 31 days. Home range may be as much as 4 Ha (9 acres) and less. Natural predators include small carnivores, avian raptors and snakes. Ectoparasites include fleas, lice, mites, botfly larvae; probably some endoparasites are present in some populations.
One of my favorite wildlife species is known as a “pika” or rock rabbit. A member of the rabbit order, Lagomorpha, these small critters inhabit talus slopes and rock slides generally at higher altitudes in western North America– north to Alaska. Pikas are unique in that they cut green vegetation, allow it to dry, then feed upon it during cold winters. They do not stockpile seeds and other food as do chipmunks and some rodents. In the late summer, it is common to see these small animals, perhaps the size of a rat, carrying green vegetation to piles near their den areas within the interior of the rocky slopes. By the time winter rolls around with dense snowfall and cold temperatures, pikas have accumulated substantial piles of vegetation, now dry and cured “hay” ready for later consumption near their dens. Come spring, hay piles are greatly reduced or completely absent.
Pikas have unique vocalizations that often identifies their near presence a peculiar squeaking sound. In the summertimes, they are often seen sunning themselves on rocks near their dens. Of course, they have to be constantly vigilant due to predators which highly value them as prey. Coyotes, foxes and hawks especially keep sharp lookout for these small mammals as tasty treats.
A recent article in the IdahoStatesman by Rocky Barker reviewed research on American pikas by biologist Erik Beever, summarized as follows: Pikas are disappearing from parts of Idaho to California where as they were found as recent as 10 years ago. Factors responsible for their disappearance are thought to include less winter snow and summer rain although other habitat features still seem adequate. Apparently there have been major pika distributional losses due to precipitation in the Great Basin over the past century. Precipitation in the form of insulating snow to minimize exposure to extreme cold and stress is probably an important factor. Summer precipitation affects food availability. Over the past ¾ of a century, snowpack has declined and temperatures have slowly been rising.
Unexpectedly, smaller pika populations thought to be more prone to extinctions in 1999 actually increased in numbers in 2003 to 2008. In Idaho, pikas continue to thrive in the alpine areas of the Sawtooth Mountains, but also seem to have done well in the high desert–Craters of the Moon near Arco. This area is dominated by lava flows, caves and fissures dating 2,000 to 15,000 years ago.
As in other locals, Idaho typical pika habitats are talus, broken rock slides, steep mountainsides, base of cliffs. In these habitats, pikas with their thick fur, cannot survive temperatures as warm as 77 to 85 degrees during the summertimes. However, in Craters of the Moon National Preserve lava, these animals seemed to thrive, probably due to cooler “microrefugia” within the lava deposits which serve as efficient insulation against high temperatures. In the nearby Crater’s talus fields, pikas known to be present in the 1980’s are now gone.
In my own experience, I have trapped pika’s in Laramie, WYs, Snowy Range, in the Gray’s River (WY) area and observed them at Cottonwood Lake of Star Valley, WY, and in SE Wyoming’s Bridger National Forest, and in the Wasatch Mountains of southeastern (Bear Lake) Idaho. In the latter areas where previously seen, they are no longer present. Pikas are a fascinating little creature and are well worth any effort made to observe them in their natural habitats.
About Pikas or Rock Rabbits:
Ochotona princeps, and O. collaris are scientific names for the two North American species; the former is southern in distribution, the latter northern. Of the total of 18 surviving species, 16 are mostly in Asia. Their fur is grayish to brownish and they have no visible tail. They are diurnal in activity. Two to five young are born in May-June and in July- August (two litters per year) with a gestation period of about 30 days. Animals are colonial and each animal has its own territory within the colony, which it defends and lives in throughout life. Territoriality is maintained due to limited numbers of nest sites and the necessity of defending food hay piles. Females are monogamous. Males provide no parental care and are aggressively excluded following birth of litters. Few live beyond five years, maximum of seven. Predators include hawks, foxes, martens, fishers, wolverines, lynxs, coyotes, bears, weasels and ermines. The latter are able to enter pika dens due to their slender bodies.
See Forsyth, A. 1999. Mammals of North America – Temperate and Arctic Regions. Firefly Books, Willowdale, Ontario.
The jumping mouse, genus Zapus, is distributed pretty much throughout North America north of Mexico. There are three species, Zapus hudsonius (meadow jumping mouse), Zapus princeps (western jumping mouse) and Zapus trinotatus (Pacific jumping mouse). The meadow jumping mouse is found in eastern US and Canada, extending northerly into Alaska. The western jumping mouse is found in western states and into Canada. The Pacific species inhabits the Pacific coast in California and extends northward along the shoreline and more into the interiors of Oregon, Washington, and British Columbia.*
The jumping mouse is slightly larger than the common house mouse. It has a long tail and hind legs much longer than fore legs. Fur is different shades of brown with white or whitish underparts. The western jumping mouse has bicolored pelage, with pale to grayish brown above, white to yellowish-white below.** It is well adapted to live in a variety of habitats, from grassy fields, vegetation along bodies of water, and in dense vegetation in wooded areas. The jumping mouse moves with a series of zig-zag hops and horizontal leaps. When fighting, the mouse squeaks. It rattles its tail, kicks with hind limbs, pushes with their forelimbs, and rattles its tail. Runways are obvious, cluttered with grass clippings. Jumping mice are mostly nocturnal in activity and are goos swimmers.
One of the remarkable characteristics of the jumping mouse is its ability to hibernate; it is one of the longest mammalian hibernators. From one-half to two-thirds or more of its life is spent in hibernation. Length of hibernation varies generally from September to April. Pre-hibernation deposition of fat depends on abundance of seeds and green vegetation. There is significant weight loss during hibernation and mortality occurs among individuals with insufficient fat deposits, especially among juveniles. If spring soil temperature do not change to above 8.0 to 9.5 degrees C, and if body weight drops below 18 to 19.5 g, animal mortality is high. Arousal from hibernation usually occurs when soil temperatures rise above 9 degree C in the spring.
Hibernation nests vary among species and individuals. Some are often found 0.5 m. or so below ground surface and often constructed of grass.
*Hall, E. R. 1981. Mammals of North America. Vol 2. John Wiley & Sons, New York.
**Hart, E. B., M. C. Belk, E. Jordan and M. W. Gonzalez. 2004. Zapus princeps. Mammalian Species, No. 749.
About Zapus, the Jumping Mouse
The three species of the Zapus jumping mouse (hudsonius, princeps, trinotatus) have much in common. Fossil forms are found in Oklahoma, Kansas, Tennessee and other areas. They normally hibernate from fall to the spring. During hibernation, breathing slows, body weight diminishes, and body temperature and oxygen consumption is lowered. Three to seven young are usually born in June after a gestation period of around 20 days. There may be more than one litter born per season. Zapus are found in a wide variety of habitat along streams and ponds and in forest vegetation. They are omnivorous feeding mainly upon the fruits and seeds of vegetation and insect larvae and fungi. Predators include owls, hawks, bobcats, weasels, skunks, raccoons, and garter snakes. They are hosts to parasites including trematodes, nematodes, bacteria, protozoans, ticks, chigger mites, fleas, botflies, etc. Home ranges are less than one acre.
As humans, we have an insatiable tendency to number, name and organize anything and everything. Often, this is healthy and it has led to our current system of animal nomenclature. Each of the following groups, from the largest to the smallest, contain progressively fewer members, though closer similarities: the largest group is Kingdom proceeding to Class to Order to Family to Genus, finally down to the smallest category, the Species. Animals of the same species are most alike, the same “kind” so to speak.
The classical definition of a species is two animals (male and female) that cannot produce fertile offspring when mated with one another. These are said to be reproductively isolated from each other. A simplistic example is a horse mated with a donkey. Even though offspring are produced (mules), they (mules) are sterile and cannot reproduce. The horse and the donkey, then, satisfy the definition of each being a separate mammal species.
The single best method for determining whether animals from different peopualtions are each valid and separate species is to actually allow mating to occur. That is to allow opposite gender representative individuals from questioned populations (male from one, female from another) to reproduce. Careful observation of offspring (if any) fertility will indicate whether or not they are reproductively viable. There are obviously a number of challenges in accomplishing this. Difficulties with this approach include:
To have a secure enclosure location where there is no chance for escape yet still large enough for several concurrent experimental matings is difficult. An enclosure for fossorial animals is necessary where boundary retaining walls are buried deep enough in the ground to deter escape by burrowing. When animals from other places are transported and placed in new and strange enclosure environments, escaping animals often disrupt normal resident animal’s well being. There are numerous unfortunate examples of exotic (non-local, foreign) animals being transported either purposefully or otherwise into new habitats. Often these lack natural controls (predators, disease, etc.) which kept population numbers balanced in the original foreign habitats. In new and similar habitats, exotic animal numbers may subsequently explode (as starlings, English sparrows, Norway rats in the U.S., rabbits in Australia, etc.) which causes unimaginable trauma and biological upheaval in formerly balanced ecosystems.
Also, it is often difficult for a researcher with little financial research support to live trap and subsequently to transport specimens from distant location to a central enclosed study facility and then manage them successfully.
Time. There must be ample time for mating, gestation, birth, growth to adults of the offspring and opportunity and time for them to mate and reproduce. Time for all of this to occur may require up to several years. Complications such as different matings, escapes, and unexpected mortality conceivably could add substantial time to the overall process.
It is often a challenge to meet governmental legal requirements and red tape. Concerns regarding transport of live specimens possibly carrying disease organisms and/or parasites from one area or country or state into another must come into consideration. Awareness of animal care guidelines is necessary.
Since actual mating experiments are rarely possible, alternatively, biologists usually go about it a different way. They seek to resolve systematic relationships by trapping a number of samples from each subject species or population being studied, one group at a time. Normally, sampling of at least 30 animals (from each population/species) is necessary for good statistical comparisons–all of which requires extensive work and resources. Measurement and analyses of representative tissues in the laboratory is labor intensive. Sophisticated statistical analyses usually follows.
Biologists work with a process called systematics, an approach using various comparison approaches/techniques in researching animal relationships. Some of the so-called important “sub-disciplines” of systematics include morphology (anatomy), physiology, phylogeny and karyology. Morphology refers to measurement and appearance differences in physical form; physiology refers to body functions; phylogeny includes consideration of relationships of near and far relatives (it is helpful to be able to identify a common ancestor); and karyology which has to do with counting and comparing chromosomes, then constructing karyograms (charts showing all individual photomicroscopically enlarged chromosomes).
This overall approach involves looking at and researching and measuring and comparing many kinds of characters from each animal group, including some of the following: fur color, behavioral aspects, size measurements, dental structure, skull measurements, activity patterns, mating habits, food preferences, hibernation (if present), tissues and DNA proteins, etc. Aboveground-dwelling animals with rapid mobility and extensive home ranges add additional challenges to animal systematists. This is because there is much greater selection of mates to pass genetic material over a larger geographical area.
Burrowing mammals offer a fascinating avenue for study of speciation of animals with limited aboveground mobility. Among these animals, genetic material transfer is much less universal. Potential mate selection is much more limited. Small subterranean-dwelling mammals are much more likely to be able to achieve some degree of isolation. The effects of natural selection over time become more obvious and significant. Some fossorial animals include North and Central American pocket gophers, African mole rats and South American tuco-tucos. Pocket gophers are basically similar in North and Central America and are nearby real-life examples. In South America, tuco-tucos occupy convergent (similar) habitat niches, spending most of their lives underground. Most tuco-tucos are solitary, although one tuco-tuco species is colonial. Mating probably takes place underground. They construct long and complex tunnel systems which contain chambers for food storage as well as nesting chambers; food is strictly plant parts, mostly roots and stems. Tuco-tucos are named after their vocalization. Tuco-tucos vary in color, though usually with some shade of brown.
The tuco-tuco family is called Ctenomyidae. There is only one genus, Ctenomys, with over 60 described species.* These small mammals are found from southern Peru south to Tierra del Fuego in Chile, with some species in southeastern Brazil, Paraguay, Argentina and Bolivia. One is a newly identified, endangered, species from southern Brazil.**
Tuco-tucos are somewhat problematical to scientists in terms of identifying similarities and differences among the 60 plus described species. Some of the troubling issues faced when researching the various species include presence of varying numbers of chromosomes (26 to 56 but with constant amount of DNA) and differing skull anatomy among the widely distributed 60+ species. Other unique qualities of the tuco-tuco include some with chromosomal polymorphisms (meaning that shapes of chromosomes are not consistent), varying DNA, limited genetic exchange with nearby populations, differences in kinds of occupied habitats, and possible subjection to extreme environmental selection due to differences in soil texture, depth, temperatures.
Many tuco-tuco species have been physically isolated (disjunct) from other population groups for many years. This has resulted in selection and adaptation of some body characters, body function and behaviors in response to the habitat–subterranean niche– “pressures” driving natural selection
A good example of a speciation study is recent research done by Thales, de Freites, Fernandes, Fornel, and Roratto.** They researched a population of tuco-tucos in a rather small area (~ 500 km2 ) in southern Brazil. These researchers obtained a total of 34 specimens, 11 males, 23 females from six known localities. They sampled body tissues and measured skull bone characters and then compared these to known information from other species of tuco-tucos. Primary differences found included chromosome numbers and arms (2n=50; 68 autosomal arms), skull anatomy (morphology), and mitochrondrial cytochrome-b gene. Comparing these, the researchers found that differences were significantly enough from other tuco-tucos so as to merit these a separate species. The new species was named Ctenomys ibicuiensis.
The cytochrome-b analysis resulted in a phylogenetic tree construction indicating all relationships within the genus. Skull size and shape analyses showed C. ibicuencis as having a more compact and smaller skull than nearest neighbor populations of C. torquatus species group. However, the authors state that “chromosomal morphology is the most important diagnostic characteristic that differentiates the karyotype of the new southern Braazilian species,” specifically with a large 1st metacentric chromosome as a diagnostic trait for the new species, supported by geometric morphometric and phylogenetic analyses. The C ibicuencis and C. minutus populations which both have 50 chrpomosomes are very different with the latter having 14 biarmed and 10 acrocentrics.
Systematics, as shown in this example, utilizes different parameters, in concert, to serve altogether as diagnostic rationale for identifying species.
*Eisenberg, J.F. and K. H. Redford. 1999. Mammals of the neotropics, vol. 3. University of Chicago Press, Chicago.
**de Freitas, T.R.O., F.A. Fernandes, R. Fornel, and P.A. Roratto. 2012. An endemic new species of tuco-tuco, genus Ctenomys (Rodentia: Ctenomyidae), with a restricted geographic distribution in southern Brazil. J. Mammal., 93(5):1355-1367.
While at the University of Oklahoma working on a graduate degree, I became interested in pocket gophers (family Geomyidae). These small furry mammals are widespread across the western U.S. into Canada, Mexico and in Central America. One of the most interesting aspects of pocket gophers is their life habit of living in the underground niche. They are rarely seen aboveground. Unless your cat has dragged one home or you have flooded them out of their burrows when irrigating or watering your lawn or field, you probably have never seen one. If you live in western North America, Florida, just east of the Mississippi River or Central America, you have seen their irregularly-shaped dirt “mounds” on the ground surface. As new tunnels are constructed, pocket gophers get rid of excess soil from their diggings by pushing it to the surface. Their overall size varies from the size of a mouse to that of a large rat, depending on where they live. They are solitary and well adapted to living in dark tunnels. They have small eyes, small ears, and sharp claws with which they dig most efficiently— they have no vocalization and are vegetarians.
As is often the case with animals present on one continent occupying a certain ecological niche, there are often counterparts occupying the same niche on other continents. These may have anatomical and behavioral similarities, but are typically unrelated genetically. Biologists call this “convergence.” Similar niche selective factors have resulted in similar (sometimes different) anatomy and behavioral adaptations.
In the Eurasia, the mole-rat (family Spalacidae) occupies a similar underground niche. In South America the convergent underground-dwelling (also called fossorial) small burrowing mammals are called tuco-tucos. Tuco-tucos fill an underground niche and are similar to North and Central American pocket gophers. They are likewise well adapted to underground life. Their adaptations* have resulted in selection for some of the same characters present in their northern counterparts (small beady eyes, small ears, sharp digging fore feet claws, vegetarian food habits, etc). However, there are also differences between them: Tuco-tucos are named for the “calls” or vocalizations they make.** They are more prone to gather vegetation aboveground than their northern continental neighbors. They weigh 100 g. to 700 g. Their fur is typically some shade of brown and they have very short tails.
At the present time, there are more that 60 described species in a single genus, Ctenomys. They are found in a number of South American countries, from southern Peru to Tierra del Fuego: Peru, Chile, Brazil, Paraguay, Uruguay and Argentina in a variety of habitats. Tuco-tucos prefer loose sandy soils, but are not restricted to this soil type. One species (C. lewsi) has aquatic habits and constructs its burrows near streams and water. Often its burrows are filled with water. Another species (C. sociabilis) forms a true colony with interconnected tunnels but this is unusual for the genus.
*Eisenberg, J.F. and K. H. Redford. 1999. Mammals of the Neotropics, vol. 3. University of Chicago Press, Chicago.
**Lord, R.D. 2007. Mammals of South America. The Johns Hopkins University Press, Baltimore.
About Tuco-Tucos (Genus Ctenomys):
Tuco-tucos have exploited the fossorial ecological niche. There are over 60 named species from southern Peru to Tierra del Fuego, Paraguay, Brazil, Uruguay, and Argentina.* Most are solitary and spend most of their lives underground. Gestation length may be as long as 130 days. Young are born with open eyes and fully furred. Litter size is 2 to 4. Mating likely takes place in burrows. Their tunnel systems are long with side chambers containing food storage and nests. Burrows vary in depth from 30 cm to 50 cm, with a diameter of 5 cm. to 6 cm. They feed on roots and grasses. The genus name Ctenomys stems from the fringe of comb-like bristles on the sides of their feet (Cteno = comb; mys = mouse.**