Paragraph 1：There are several important features of tropical mammals and their habitats that differentiate them from temperate-zone mammals. First, tropical mammals face different environmental stresses than do temperate-zone mammals, and they respond to stresses in different ways. Many temperate-zone mammals, of course, must endure extreme variation within a year; from cold winters with snow and low food supplies to hot summers with dry weather and abundant food. Many mammals respond with hibernation, staying more or less dormant for several months until conditions improve. Tropical mammals, except in the high-altitude mountains, do not encounter such extreme annual changes, but they do face dry seasons, up to five months long, that sometimes severely reduce food supplies. For some surprising reasons, they cannot alleviate this stress by hibernating, waiting for the rainy season to arrive with its increased food supplies. When a mammal in Canada or Alaska hibernates, many of its predators leave the area. This is not the case in the tropics. A mammal sleeping away the dry season in a burrow would be easy prey to snakes and other predators. Moreover, a big danger to sleeping mammals would be army ants. These voracious insects are very common in the tropics and would quickly eat a sleeping mouse or squirrel. Also, external parasites, such as ticks and mites, which are inactive in extreme cold, would continue to be very active on sleeping tropical mammals, sucking blood and doing considerable damage. Last, the great energy reserves needed to be able to sleep for an extended period through warm weather may be more than any mammal can physically accumulate. Therefore, tropical mammals need to stay active throughout the year. One way they counter the dry season’s reduction in their normal foods is to switch food types seasonally. For instance, some rodents that eat mostly insects during the rainy season switch to seeds during the dry season; some bats that feed on insects switch to dry-season fruits.
