TAILIEUCHUNG - Linzey - Vertebrate Biology - Chapter 11
C H A P T E R 11 Movements Vertebrates are mobile animals that move about to secure food, to locate suitable homes and nesting sites, to avoid unfavorable periods of the year, and to find mates. Some species move very little during their lifetimes. | Linzey Vertebrate Biology 11. Movements I Text The McGraw-Hill Companies 2003 CHAPTER 11 Movements INTRODUCTION Vertebrates are mobile animals that move about to secure food to locate suitable homes and nesting sites to avoid unfavorable periods of the year and to find mates. Some species move very little during their lifetimes whereas others such as golden plovers Pluvialis dominica and elephant seals Mirounga angustirostris may cover over 20 000 km annually. Some movements are seasonal or annual whereas other movements occur only once in a lifetime. Orientation consists of two different phenomena the control of an animal s position and stability in space and the control of an animal s path through space Wiltschko and Wiltschko 1994 . Movements undertaken by vertebrates can be categorized on the basis of where and when they occur home range movements dispersal invasions migration homing and emigration. Alternatively movements can be classified by the mechanisms by which the movement is achieved vision hearing olfaction navigation or compass orientation. Our understanding of the way in which animals know how when and where to orient and navigate around their environment has grown considerably over the last few decades. HOME RANGE Home range is highly variable and is often difficult to define. It is the area around the home of an individual that is covered by the animal in its normal activities of gathering food mating and caring for its young. Home ranges may be linear two-dimensional or three-dimensional. Home range generally is correlated with the size of the animal. Small forms usually have relatively small home ranges whereas larger species normally have larger home ranges. Among mammals of the same size carnivorous species such as cougars Felis concolor generally have larger home ranges than herbivorous forms such as white-tailed deer Odocoileus virginianus . A carnivore must expend considerably more energy and cover a much greater area in order to secure .
đang nạp các trang xem trước