Small Mammals

Small MammalsFor mammals, one obvious advantage of smallness in the natural environmentpertains to easy concealment from predators: by hiding rather than fleeing, asmall mammal can cut back on energy expended for locomotion – a crucialeconomy for hot-bodied small mammals. Most species of small mammals areeither active mainly at night or at dawn and dusk, and therefore are faced withpredation pressure more from flying predators than those on land. However,foraging below the leaf litter, under the snow (subnivean), or in thesubterranean environment certainly reduces vulnerability to capture fromabove. For small mammals such as insectivores, rodents, and smallmarsupials, concealing coat coloration adds additional advantage to small sizein avoiding detection from aerial predators. Also, small size affords a widerrange of available food types. Small mammals focus their foraging on theavailability of resources to meet their energy needs. Some small mammals,such as mice, consume almost everything they come in contact with, includinginvertebrates, plant material such as rhizomes, fruits, seeds, leaves, flowers,ferns, and fungi.The word “expended” in the passage is closest in meaning toA.savedB.producedC.neededD.usedAccording to paragraph 1, all of the following help small mammals avoiddetection by predators EXCEPTA.going to a place they cannot be seenB.searching for food under the ground surfaceC.having coat colors that make it difficult to be noticedD.focusing on a small number of food typesBased on paragraph 1, which of the following can be inferred about thepredators of small mammals?A.Land predators catch small mammals more effectively during the daythan at night.B.Flying predators can easily spot small mammals moving below theleaf litter.C.Land predators are the main source of pressure on the small mammalpopulation.D.Flying predators are especially well suited to catching small mammalsbeneath the snow.Small size also enables small mammals to utilize microhabitats that are wellinsulated from fluctuating temperatures in the ambient environment. Smallbodies can lose heat rapidly due to their high surface-area-to-volume ratios;they must conserve energy by reducing conductive heat loss. By living insubterranean tunnels under forest floors, below the grass cover of prairies, or,better yet, in subnivean runways below a blanket of snow, small mammals areable to reduce heat loss in spite of fluctuating ambient temperatures. Smallsize enables these mammals to utilize microhabitats characterized byimproved microclimatic temperatures and humidities. Another advantage ofbeing a small mammal is the high fertility rate seen in many species. Mostsmall mammals have short life spans, short generation times, and highturnover rates; as a consequence, changes in the genetic composition of apopulation may occur in a short time. Such mechanisms provide populations ofsmall ...