黑熊?灰熊?棕熊?北極熊?

其實「灰熊」是「棕熊」的其中一種啊！
因為有些「棕熊」看起來是灰色的，所以「棕熊」有時被稱為「灰熊」。
原因就是這樣簡單。

而事實上，生物學上的分類只有棕熊而沒有灰熊。
請先看以下有關熊科的分類（維基百科）﹕

熊科 Ursidae



熊貓亞科 Ailuropodinae

大熊貓 Ailuropoda melanoleuca

眼鏡熊亞科 Tremarctinae

眼鏡熊 Tremarctos ornatus

熊亞科 Ursinae

棕熊 Ursus arctos
美洲黑熊 Ursus americanus
北極熊 Ursus maritimus
亞洲黑熊 Ursus thibetanus，或 Selenarctos tibetanus
阿特拉斯棕熊（北非棕熊） Ursus crowtheri (約1870年滅絕)
懶熊 Melursus ursinus，或 Ursus ursinus
馬來熊 Helarctos malayanus

就熊科的分類而言，根本就沒有「灰熊」。
另外，在 維基百科 上亦提到﹕

棕熊有毛茸茸的毛皮，呈白色、棕色、黑色或雜色；雖然叫棕熊，但是它們的毛色通常偏灰。

以下則是棕熊的五種分類，「灰熊」是其中一種。
灰熊（U. arctos horribilis）是北美洲最常見的棕熊
阿拉斯加棕熊（U. arctos middendorffi）
墨西哥棕熊（U. arctos nelsoni）
喜瑪拉雅棕熊(U. arctos isabellinus)
日本棕熊 (U. arctos yesoensis)

2007-02-19 23:29:19 補充：
網站推薦﹕在「動物星球」（Animal Planet）網站可以找到上述各種熊的資料。（絕種的「北非棕熊」除外）網站裡其中一段形容﹕　　棕熊的不同亞種源自於歐洲的北、東和西部地區、亞洲北部地區、日本、加拿大和美國 ……　　在美國，棕熊也稱為「灰熊」 (Grizzly Bear)，因為熊毛的末端呈灰白色。網址﹕http://www.animalplanet.com.tw/bears/

2007-02-19 23:31:30 補充：
更正句子﹕「生物學上的分類只有棕熊而沒有灰熊。」改為「生物學上的熊科分類只有棕熊而沒有灰熊。」

灰熊依不同地區有不同的顏色。可以有亞麻色﹐深棕色或者黑色。查網頁好像沒有怎樣用grey這個字眼



The grizzly bear, sometimes called the silvertip bear, is a powerful brownish-yellow bear that lives in the uplands of western North America. It has traditionally been treated as a subspecies, Ursus arctos horribilis, of the brown bear living in North America.



Grizzly bears reach weights of 180–680 kg (400–1,500 lb); the male is on average 1.8 times as heavy as the female, an example of sexual dimorphism. Their coloring ranges widely across geographic areas, from blond to deep brown or black. These differences, once attributed to subspeciation, are now thought to be primarily due to the different environments these bears inhabit, particularly with regard to diet and temperature.



The grizzly has a large hump over the shoulders which is a muscle mass used to power the forelimbs in digging. The head is large and round with a concave facial profile. In spite of their massive size, these bears can run at speeds of up to 55 km/h (35 mph).



Normally a solitary nocturnally active animal, in coastal areas the grizzly congregates alongside streams and rivers during the salmon spawn. Every other year females (called sows) produce one to four young (most commonly two) which are small and weigh only about 500 g (1 pound). Sows are very protective of their offspring.






圖片參考：http://upload.wikimedia.org/wikipedia/commons/thumb/5/5b/Grizzly_Bear_Yellowstone.jpg/180px-Grizzly_Bear_Yellowstone.jpg





圖片參考：http://en.wikipedia.org/skins-1.5/common/images/magnify-clip.png
Female grizzly bear in Yellowstone National Park, U.S.A.

The current range of the grizzly bear extends from Alaska, south through much of Western Canada, and into the northern Northwestern United States including Idaho, Montana and Wyoming. Its original range also included much of western and southern United States, but it has been extirpated in those areas. It is expected that the grizzly's repopulation of its U.S. range will be a slow process due equally to the ramifications of reintroducing such a large animal to areas which are prized for agriculture and livestock and also because of the bear's slow reproductive habits (bears invest a good deal of time in raising young).



Brown bears (of which the grizzly bear is a subspecies) can live up to thirty years in the wild, though 20–25 is normal.



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棕熊



外貌



棕熊有毛茸茸的毛皮，呈白色、棕色、黑色或雜色；雖然叫棕熊，但是它們的毛色通常偏灰。在棕熊的背部有一塊鼓起來的肌肉，當它們挖洞時，那塊肌肉便給予棕熊前肢的力量。它們有一雙有力的大手，有1.5米長，一掌拍下去足以殺死一頭和自身一樣大的馬鹿。不像有些大型動物，例如獅子或老虎，它們的爪子（指甲）不能伸縮，由於爪子不能伸縮，它們的爪子不是很靈活。儘管它們的爪子不靈活，那巨大的力量還是致命的。頭大而圓。儘管它們看起來很笨重，當他們跑快時時速可達56公里/時(35英里/時)。棕熊不僅快，而且很有耐力。可以以最快的速度跑幾十分鐘。當然棕熊也有弱點：儘管棕熊已經夠快了，但是它們的主要食物之一：鹿，可以以每小時67公里/時的速度跑幾十分鐘。阿拉斯加棕熊是體型最大的熊，有不少雄性阿拉斯加棕熊體長可達3米，體重可達680公斤，世界上最高的熊高達4米（是體長不是肩高）。一頭柏林動物園的熊重達1134公斤。



結論：啡色的熊可以是灰熊或棕熊。