托福阅读背景知识积累：记忆力惊人的鸟类

很多动物都会储存食物，而这需要一定的记忆力。在下面的新托福考试阅读练习资料中将介绍一种记忆力惊人的鸟类。

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Humans may be one of the smartest animals on the planet, but when it comes to remembering where things are, Clark's nutcrackers have us beat.

A relative of jays and crows, nutcrackers hide pine seeds in the ground each autumn so they have a source of food during the Colorado Rocky Mountain winter. They cache as many as 30,000 seeds in 5,000 different locations over a fifteen square mile area. Since they cannot smell the seeds buried in the soil very well, they must use their remarkable spatial memory to find them.

Nutcrackers are not the only animals that cache food. Caching behavior is seen in birds, mammals and even insects. Chickadees store collections of seeds, insects and spiders in the bark of trees or under leaves. Red squirrels cut conifer cones from trees and bury them in plant litter on the forest floor. Harvester ants bring seeds back to their nests and store them in chambers, while honey bees save nectar and pollen in their hive.

Because nutcrackers are one of the best at remembering cache locations, researchers are studying them to find out why they have such great memories. Scientists know that the nutcracker's abilities evolved because of environmental pressure. Nutcrackers with poor memories did not likely survive the harsh mountain winters. Now researchers want to find out how the brains of nutcrackers are different from other brains. They are particularly interested in the hippocampus, a small area of the brain that helps form memories. Finding out how the nutcracker's brain is different from other species may give us clues to why humans have memory problems. It may even lead to a cure for Alzheimer's disease.

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人类也许是世界上最聪明的动物之一，但说到记忆，克拉克(新泽西州)的星鸟比我们人类强多了。

星鸟属于松鸟和乌鸦的近亲，它在秋天的时候把松子藏在地底下，这样寒冷冬天的就有食物吃了。它们会储存多达30000颗种子，而且是在十五平方公里内的5000个不同位置。因为不能通过气味辨别埋在土里种子的位置，它们就必须依靠惊人的空间记忆力来找到这些种子。

关键词：背景知识 阅读材料 阅读

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