松鼠那么可爱，它们都有哪些种类呢？又有什么习性呢？阅读本文，你就会发现，松鼠不仅可爱，有时还很聪明呢！
01
There are more than 200 squirrel species worldwide, from tree squirrels and flying squirrels to chipmunks and marmots. They're all in the Sciuridae family, which is native to every continent except Australia and Antarctica.
世界上有200多种松鼠，从树松鼠、飞鼠，到花栗鼠和土拨鼠。它们都属于松鼠科，除了澳大利亚和南极洲外，其他大陆都有它们的身影。
02
Squirrels range in size from the five-inch African pygmy squirrel to relative behemoths like Indian giant squirrel (pictured above) or China's red-and-white giant flying squirrel, both of which can grow more than 3 feet long.
松鼠的体型大小各不相同，有身长五英寸的非洲小松鼠，还有体型较大的松鼠，如印度巨松鼠（如上图）或中国的红白鼯鼠，这两种松鼠都能长到超过3英尺长。
03
Squirrels have four front teeth that grow continuously, at a rate of about six inches per year. This helps their incisors endure the constant gnawing.
松鼠有4颗不断生长的门牙，每年大概会长6英寸，这成为了它们不断咀嚼食物的利器。
04
Tree squirrels mostly eat nuts, seeds and fruit, but they are omnivores. Gray squirrels, for example, have been known to eat insects, snails, bird eggs and animal carcasses when other food is scarce.
树松鼠主要吃坚果、种子和水果，但它们其实是杂食动物。比如灰松鼠在食物缺乏时就会吃昆虫、蜗牛、鸟蛋和动物尸体。
Better hope those carcasses aren't too rancid, though — squirrels, like many rodents, can't vomit. (They also can't burp or experience heartburn.)
希望那些动物尸体不会太臭，虽然松鼠和许多啮齿动物一样并不会呕吐。（它们也不会打嗝或感到胃灼热。）
05
A 2010 study found that some squirrels collect old rattlesnake skin, chew it up and then lick their fur, creating a kind of "rattlesnake perfume" that helps them hide from the smell-dependent predators.
2010年的一项研究发现，一些松鼠会收集老的响尾蛇皮，它们会将其嚼碎然后舔自己的毛，这种“响尾蛇香水”能帮助它们躲避依靠嗅觉的捕食者。
06
If you see an all-white or all-black squirrel in North America, it's probably a gray or fox squirrel in disguise. The black variation is a result of melanism, a development of dark pigment that occurs in many animals. White fur could be caused by albinism, although many white squirrels lack the distinctive pink or red eyes, instead owing their color to leucism. Some places are more prone to white squirrels, like Brevard, North Carolina, where as many as one in three squirrels have white fur.
如果你在北美看见一只全白或是全黑的松鼠，那很可能是灰松鼠或狐松鼠的伪装。松鼠变异成黑色其实是黑变病造成的，许多动物身上都会出现这种暗色素沉着。而白色的毛也许是由于白化病造成的，虽然许多白松鼠没有独特的粉色或红色眼睛，但毛却是白色的。有些地方容易出现白松鼠，如布里瓦德、北卡罗莱纳，这些地方每三只松鼠里就有一只是白色的。
07
Flying squirrels can't really fly — they just use flaps of skin between their limbs to glide from tree to tree — but it often seems like they can. Their acrobatic leaps often span 150 feet, with some species covering nearly 300 feet in a single glide.
飞鼠其实不能飞——它们只是用四肢间的飞膜在树与树之间滑翔——但它们看起来像是会飞一样。它们的“杂技飞跃”往往能跨越150英尺，而有些物种单次滑翔就能接近300英尺。
08
Squirrels communicate using complex systems of high-frequency chirps and tail movements. Studies have also found they're capable of watching and learning from each other — especially if it relates to stealing food.
松鼠利用高频叫声和尾部摆动的复杂系统进行沟通。研究还发现，它们能够互相观察和学习——尤其是在学习偷食物方面。
