This is Scientific American — 60-Second Science. I'm Steve Mirsky.
Today, November 4, is National Bison Day—celebrating the animal that last year Congress and the President designated as the official National Mammal of the United States. For good reason: the American bison, also called the buffalo, is the iconic animal that helped mold the ecology of the Great Plains and played a central role in the cultural life of multiple tribes of Native Americans, including the Arapaho and Lakota.
Today's healthy bison herds owe a lot to time their ancestors spent in, of all places, the Bronx, in New York City.
"Well, historically the Bronx Zoo played a very important role in saving bison."
Patrick Thomas, Vice President of the Wildlife Conservation Society and Associate Director of its Bronx Zoo.
"In the early 1900s when bison numbers were at their lowest and the species was facing extinction, the Bronx Zoo acquired as many bison as they could, bred them and then sent offspring from that breeding herd out west to re-establish herds in the wild."
Thomas is involved in efforts with the zoo's current herd of bison.
"Right now we're working to establish a herd of genetically pure bison at the zoo. Today there are about 500,000 bison in the U.S., but there's only about between 5- and 6,000 that are genetically pure bison. The rest have small trace amounts of domestic cow genes in them. So we're establishing a herd of pure bison, breeding them, and again our goal is to take offspring from those pure bison and establish pure bison herds out west."
In what would be a continuation of one of the earliest success stories in American conservation.
Ffor Scientific American — 60-Second Science. I'm Steve Mirsky.
11月4日是美国国家野牛日，去年国会和总统正式确立野牛为美国国家哺乳动物，并以这一天来纪念它 。此举有充分的理由：美洲野牛，又称水牛，是一种标志性动物，它帮助塑造了美国大平原的生态环境，并在阿拉巴霍人以及拉科塔族等多个美洲原住民部落的精神文化生活中发挥了核心作用 。
“目前我们正致力于在动物园里培育纯种基因的野牛群 。现在美国约有50万只野牛，但仅有约5000到6000只是纯种野牛 。其余野牛都有少量家牛基因 。所以我们培养和繁育纯种野牛群，我们的目标依然是带走这些纯种野牛后代，在西部野生环境建立纯种野牛群 。”
谢谢大家收听科学美国人——60秒科学 。我是史蒂夫·米尔斯基 。
1. designate as 标示；把…定名为；称呼；
例句：We're going to designate this room as a no-smoking area.
2. be involved in 卷入的；参与的；与…有密切关联的；
例句：So I'm involved in a different kind of campaign, to try to change enough minds to make it a new reality.
3. a herd of 兽群；畜群；
例句：A herd of elephants lolloped across the plains towards a watering hole.