ILLINOIS: NEXT GENERATION SCIENCE STANDARDS

Characteristics

Classifying animals into categories and groups based ontheir similarities and differences is the first step in studyingand understanding their origins, development and inter-dependence. In this unit, we will focus on wild mammalsthat can be found in Illinois.

Mammals have the following characteristics.

l ey are covered with hair or fur.

l ey are warm-blooded (meaning their internal bodytemperature is maintained at a constant level regardlessof external conditions).

l ey are usually born alive and relatively well-devel-oped, having grown inside the mother's body in a spe-cial organ called a uterus. e time spent developing inthe uterus before birth is called the gestation periodand varies in length from species to species (from about13 days in the Virginia opossum to 210 days in thewhite-tailed deer). ere are five mammal speciesthat lay eggs instead of giving birth to their young.ey have all of the other traits of mammals, how-ever. None of these five species live in Illinois.

l After birth the young are fed with milk that isproduced by mammary glands.

l ey have larger and more complex brainsthan any other group of animals.

Wild mammals are those species that depend uponthemselves to find the food, water and shelter thatthey need. In Illinois, raccoons, deer mice, foxes andbobcats are some wild mammals. Domesticated mammalsare those that have been bred for special purposes.

ey are related to mammals that were once wild. Cows,horses, sheep and pigs are all examples of domesticatedmammals. Domesticated mammals receive some of theirsurvival requirements from humans.

“Tame” mammals are pets. ey are domesticated animals.However, not all domesticated mammals are tame. Withmost mammal species, a single animal may become“tame” while the rest remain wild. Some mammals thatwere once domesticated have become wild again. eyare called “feral,” such as feral hogs and feral cats.

Signs

Wherever they live, mammals produce evidence of theirpresence. is evidence may be seen in the form of foot-prints or tracks in the soil or snow, indications of feeding

activity and types of habitation. Areasof soft soil, mud, sand or snow are thebest places to look for tracks. Along

stream banks or at the edge ofany body of water you're likely to

find the footprints of many kindsof animals that come thereto drink or feed.

Evidence of feeding activityincludes any collection of nuts,seeds or fruits stored in a con-

cealed spot (under logs and tree roots, orinside log piles and hollow stumps).Tooth marks on anything indicatefeeding–look for gnawed mushrooms

or chewed nuts, fruits, leaves or twigs. Areas

Background Information for the Teacher

IllinoisWild Mammals

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of bark are often chewed or stripped off as food–look fortooth marks on the exposed wood.

Signs of habitation can be interesting. Any natural cavityin a tree, stump or fallen log is likely to contain signs of useby some animal. Look for tracks, droppings (solid waste)and bits of food around the opening or signs of nestingwithin (piles of leaves, grasses or twigs).

Many mammals live underground, and any undevelopedarea will reveal openings to such dens and burrows.

Some mammals build their own homes. Squirrel nests area common sight in the trees of woodlands, parks andurban areas. Lakes, ponds, streams and swamps are likelyto contain muskrat or beaver lodges.

Activity Patterns

All mammals require some period every day or night forrest and sleep. Whether a mammal sleeps primarily dur-ing the day or at night depends on an individual species'particular habits and survival techniques. All mammalsadapt to either daytime or nighttime activity.

ose mammals that rest during the day and engage infeeding, mating and other activities at night are nocturnal.ose that rest at night and are active during the day arediurnal.

Nocturnal mammals, like bats andraccoons, have evolved inways specifically suitedto life in the dark. Batsuse echolocation, a

unique system inwhich their extremely

sensitive ears help them nav-igate through the dark. Most

other nocturnal mammals havelight-sensitive eyes and darklycolored fur or natural camouflage

making it difficult for predators to find them. ese mam-mals spend most of the day sleeping in dens or burrows.

Diurnal mammals, like tree squirrels, have evolved bene-ficial ways for daytime living. Most have developed pro-tective coloration or camouflage appropriate to theirdaytime habitat that makes them less visible to predators.Such mammals' eyes are adapted to bright light, and eachmammal has its own special means of escape or protec-tion from predators. For instance, squirrels are very fastand agile, allowing them to outrun or outmaneuver theirenemies. Diurnal mammals take their rest at night in dens,nests or burrows.

Young Mammals

Most mammals are viviparous, which means they givebirth to living young. e exceptions are the duck-billedplatypus and four species of echidna that live in Australiaand some nearby islands. ese five mammal species layeggs from which their young hatch.

Some young mammals, like mice, rabbits and bats, areborn blind and hairless, while others, such as the white-tailed deer, are developed enough to move about with theparent soon after birth.

After birth, all newborn mammals are nourished withmilk that is produced in the mother’s mammary glands.is milk is composed of water, fats, proteins, sugars andmineral salts. Mammals whose young grow the fastestproduce milk with the highest protein content.

Weaning usually occurs after the young can eat solid food.Small rodents generally nurse for a week and a half to threeweeks. Badgers can eat solid food in the first month butare suckled for four or five weeks.

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ILLINOIS: NEXT GENERATION SCIENCE STANDARDS

As physical development progresses, behavioral develop-ment also occurs. Behavior patterns are either instinctive,learned or a combination of both. Instinctive behavior isautomatic and triggered internally, while learned behav-iors are picked up by imitating the parents and throughplay among siblings or other young.

As young mammals mature, their dependency on theirparents decreases, and they become independent.

Mobility

Almost all animals are mobile. To find food, shelter andmates, avoid predators and interact with their environ-ment, animals must have the ability to move.

Mammals live in a variety of environments and haveadapted different strategies for locomotion. ese strate-gies are directly related to the specific kind of environmentin which they live. Most mammals have four limbs withtheir related paws, claws or hooves.

Mammals that live undergroundin burrows, such as moles and badg-

ers, have claws on their forelimbs designed fordigging and crawling through dirt.

Predatory mammals that chase their prey, like bobcats,have feet with thick, rough pads for traction and sharpclaws for grabbing. Deer and other grazers have flat, hardhooves for solid support on soft earth and kicking for de-fense. Beavers and muskrats, which spend most of theirlife in water, have webbing between their toes. Mammalsthat climb, like squirrels, have very sharp, short claws forholding. In most cases, the greater a mammal’s need forspeed, the longer its legs will be in proportion to the restof its body.

The most unusual examples of locomotive adaptationamong mammals are present in bats and flying squirrels.In the former, the forelimbs, especially the “finger bones”and the skin between them, have evolved into fullyfunctional wings. Flying squirrels have large flaps of skin

connecting their “wrists” to their “ankles” enabling themto glide great distances between trees or branches.

Hibernation

Survival may be difficult for mammals in Illinois, partic-ularly when harsh, prolonged winters drastically reducethe natural food supply. Some mammals use hibernationto deal with these conditions. Hibernation is a state ofextremely reduced metabolism.

Many mammals use varying degrees and lengths of dor-mancy, or inactivity, to conserve energy and survive peri-ods of limited food supply. Skunks and raccoons, forinstance, “den up” during extremely cold weather, remain-ing in their burrows and living off excess body fat, whilenot actually hibernating.

Hibernation involves drastic reductions in a mammal’sbodily functions as well as physical activity. Body temper-ature drops dramatically, as do heart and breathing rates.From a normal body temperature of 95ºF, the temperatureof a hibernating mammal may be as low as 36ºF. A normalheart rate of more than 100 beats per minute may dropto only four or five, and breathing may slow to less thanone breath per minute. Ten wild mammal species in Illinoishibernate: little brown bat; Indiana bat; southeastern bat;northern bat; eastern pipistrelle bat; big brown bat; wood-chuck; Franklin’s ground squirrel; thirteen-lined groundsquirrel; and meadow jumping mouse.

Prior to the hibernation period, these mammals accumu-late a thick layer of excess body fat that supplies them withthe energy needed to survive. A hibernating mammal maylose as much as one-third of its total body weight duringhibernation.

Scientists have discovered that even during hibernationthere are periods of wakefulness, which become more

ILLINOIS: NEXT GENERATION SCIENCE STANDARDS

frequent as the hibernation period comes to an end. Exter-nal temperature is a factor in these periods of sporadic ac-tivity. For each species there is a critical temperature abovewhich they will awaken, and all will awaken temporarily ifthe temperature drops so low that they are in danger offreezing. Wakening allows mammals to move to a deeper,warmer chamber or to warm up a little—by shivering ormoving around—until the temperature moderates.

As spring approaches the air warms, food supplies areonce again sufficient, and the hibernating mammals re-turn to normal activity.

Feedingere are three types of mammal teeth: incisors (used forcutting and gnawing) located in the front and center ofone or both jaws; canines (used for stabbing and tearing)located on each side of the incisors; and premolars andmolars (for grinding and shearing) situated along the sidesof the jaws.

Because each tooth type is designed for specific functions,they have evolved differently in different mammal species,depending on eating habits. Based on these relationships,mammals are categorized into four feeding groups.

l Herbivores are mammals that eat mainly vegetation.ere are two sub-groups: plant-tearing mammals(deer) and plant-gnawing mammals (beavers, squirrelsand mice). Plant-tearing mammalshave incisors in their lowerjaws only, no canines at alland flat, sharp-edged mo-lars. is arrangement is bestfor tearing leaves, stems, barkand grasses. Plant-gnawers havesturdy, sharp incisors on both jaws for cutting throughnuts, bark, wood and grasses. ey lack canines andhave flat molars for grinding.

l Carnivores, or meat-eating mammals (such as coyotes,bobcats and foxes), have small but sharp incisors

in both jaws for grabbing and holding;long, fanglike canines for

stabbing and tearing; andlarge, sharply edged pre-

molars and molars for slic-ing through flesh, bone,

skin, scales, fur and feathers.

l Insectivores, or insect-eating mammals (like shrews,moles and some bats), havelong incisors for picking in-sects out of dirt and leavesand small but sharplyedged canines, premolars andmolars for chewing hard-shelledbeetles, other insects and worms.

l Omnivores (such as raccoons,opossums and humans) eat almostanything edible. ese mammals de-velop all three types of teeth, with noone category more prominent thanthe others.

Among the mammal species in Illinois are some known aspredators. From bobcats and foxes to raccoons andweasels, they share a common behavioral trait: they catch,kill and eat other animals (called prey).

ere are different degrees of predation. Some strict pred-ators, such as bobcats, eat only meat. But other mammals,such as raccoons and opossums, eat berries, nuts andplants in addition to catching and eating prey.

Most predators are prey to other, larger predators. Aweasel that eats a field mouse may then be dinner for abobcat. ose few predators that are not prey to othersare called top predators.

Both predators and prey are links in what is called a foodchain. Food chains are the routes along which energy flowsthrough the living world.

is energy always starts with the sun. rough theprocess of photosynthesis, plants use the sun’s energy toproduce food. Animals such as rabbits and deer eat theplants and transfer the energy from the plants’ stored foodinto their own bodies only to become prey to the preda-tors, who transfer the energy to themselves.

But the flow of energy doesn’t end there. Even top pred-ators eventually die, and their bodies become food forscavengers, those animals that eat dead animals andplants. Bacteria and fungi break down bones, scales, furand feathers into the simplest chemical compounds.ese compounds become the nutrients in the soil that

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are the raw materials for plant growth. us the foodchain becomes a closed cycle with no real beginning andno real end.

Most food chains overlap (individual species of plants andanimals may be links in the food chains of several speciesof predator) and the entire system becomes a food web.

Status

Although extinction is a natural process, extensive and ex-cessive human interaction with the environment hasgreatly increased its rate. Habitat destruction is the singlegreatest cause of extinction. Other human-related causesinclude habitat damage, unregulated or illegal commercialand personal use, disruption of migration routes andbreeding behaviors, contamination by pollutants, andcompetition or predation from artificially introducedspecies. Some experts expect extinctions of plants and an-imals to increase from the current rate of one species peryear to 100 per year in the near future.

In Illinois, in 2009, a total of 355 species of plants and an-imals are endangered, and 128 species are threatened.ere are five species of endangered mammals and fourspecies of threatened mammals. Rare species, though notin immediate danger, are few in number. Some specieshave always been rare because their natural range does

not include much of Illinois or because they have limitedhabitat preferences. reatened species are those still presentin their natural range, but whose numbers are declining andare likely to become endangered in the foreseeable future.Endangered species are those in immediate danger ofextinction as a breeding species. Extirpated species arethose that have become eliminated from a portion of theirrange. For instance, elk and bison have been extirpatedfrom Illinois.

Early settlers in Illinois found a vast array of plants and an-imals living in the territory’s clear streams, wide prairiesand extensive forests.

In the 1820s, forests covered about 38 percent of the state;the remainder was mostly tallgrass prairie and wetlands.Today, about 14 percent of the forest and one percent ofthe original prairie remain. More than nine million acresof natural wetlands have been reduced to less than500,000 acres.

Such drastic loss of habitat—whether the result of modernagricultural practices, urban sprawl, pollution, sedimenta-tion, habitat fragmentation or flood control activities— isthe most serious threat to the ultimate survival of Illinois’wild mammals.

Since human activity is the primary cause for this habitatreduction, humans are also responsible for controllingand/or reversing this devastating trend. e Illinois Depart-ment of Natural Resources (IDNR) administers a numberof programs that help to maintain current habitats andslow further habitat loss.

Illinois Acres For Wildlife, a voluntary program, involvesrural and urban landowners who want to help providewildlife habitat on their property. e landowners, in co-operation with an IDNR biologist, set goals for their land.

Hunting and trapping are highly regulated activities inIllinois. Laws limit when, where and how many animalsmay be taken by hunters and trappers and keep thesespecies from becoming endangered. Fees collected fromhunters and trappers for licenses, special stamps and ex-cise taxes go toward conservation programs that benefitall wildlife species.

e Illinois Nature Preserve System includes more than350 nature preserves across the state, encompassing atotal of more than 46,000 acres (as of 2009). ese preserveswere created to keep unique areas of the state undeveloped

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for scientific research, education and public enjoyment.These areas provide homes to a wide diversity of bio-logical treasures and harbor many of Illinois’ rare andendangered species.

rough education and a commitment to the impor-tance of preserving our natural heritage, we must allstrive, both individually and as a society, to learn to sharethe world with all living things.

Equal opportunity to participate in programs of the Illinois Department ofNatural Resources (IDNR) and those funded by the U.S. Fish and WildlifeService and other agencies is available to all individuals regardless of race, sex,national origin, disability, age, religion or other non-merit factors. If youbelieve you have been discriminated against, contact the funding source’scivil rights office and/or the Equal Employment Opportunity Officer, IDNR,

One Natural Resources Way, Springfield, IL 62702-1271; 217/785-0067; TTY 217/782-9175.is information may be provided in an alternative format if required. Contact the DNRClearinghouse at 217/782-7498 for assistance.

Next Generation Science Standards © 2013, Illinois Department of Natural ResourcesDNR 44 – 10/13 • IOCI 14-0162