113 學年度學測英文 第 49 題

Many animals are known to live and move in groups to secure food and avoid predators. Over the years, people have been curious about the way they deal with disturbances arising from the environment, and the operations underlying their responses as a group. Studies on jackdaws and turtle ants may provide some insights into the issue.

Jackdaws（寒鴉） Jackdaws are birds in the crow family often found in the English countryside. They are highly social birds and often travel in large flocks. Normally, the birds enjoy a smooth flight together as a group when "commuting" between two locations, such as from their nesting site to their feeding ground. However, if a predator (such as a fox) is present, the pattern of their flight will change immediately. Instead of paying attention to all the other members and following the group pattern, they now focus only on the birds within a fixed distance from them, based on information coming from other members. By doing so, the flock members are able to keep a safe distance between themselves, and thus avoid crashing into each other while they flee from the predator.

Turtle ants（龜蟻） Turtle ants often live in the cavities of dead branches in American forests. They have evolved search strategies to link their food source to their nests. They travel entirely along tree branches and vines, laying down trails of pheromone (a chemical substance) behind them so that other ants can follow. The trails connect the ants' colonies and sources of food, forming a sort of communication network. However, since these trails can easily be broken by wind or rain, the ants have to find new paths to get around the broken points and reestablish the network. Often they have to work together to explore alternative routes many times before they finally settle on the most efficient one. By working collectively, the ants are able to improve the efficiency of their network and adapt to their ever-changing environment.

（原文附寒鴉與龜蟻照片各一張，僅為配圖，與作答無關，此處從略。）