两头穿越苏西特纳河的驯鹿，美国阿拉斯加 Caribou crossing the Susitna River during the autumn rut, Alaska (© Tim Plowden/Alamy)

两头穿越苏西特纳河的驯鹿，美国阿拉斯加 Caribou crossing the Susitna River during the autumn rut, Alaska (© Tim Plowden/Alamy)

令人印象深刻的时刻 Time to make an impression

Caribou rutting season in Alaska

It's that time of year when Alaskan caribou are beginning to feel a little frisky. From late September until early November, males will be strutting their stuff, locking antlers with one another, and competing for the attention of females in hopes of furthering the species. Successful males will mate with 15-20 females a season. After the rutting season males will shed their antlers while females keep theirs until spring. In today's photo we're looking at some caribou in southcentral Alaska crossing the Susitna River.

Alaska has 32 distinct caribou herds. It's likely today's caribou are members of the Nelchina herd, which roams across about 20,000 square miles in the high basin surrounded by the Talkeetna, Chugach, Wrangell, and Alaska ranges. The Nelchina herd is among the most studied and recognized of Alaskan caribou partly because their range is relatively close to the major human population centers of the state. The herd has provided food for Alaskans for hundreds of years and its population is maintained through carefully monitored hunting regulations. But caribou populations can fluctuate from one year to the next depending on the availability of food and severity of the weather.

阿拉斯加驯鹿发情季节

每年的这个时候，阿拉斯加驯鹿开始感到有点活泼。从9月下旬到11月初，雄性将昂首阔步，相互锁住鹿角，争夺雌性的注意力，以期进一步丰富物种。成功的雄性每季度将与15-20只雌性交配。发情期过后，雄性会脱掉鹿角，而雌性会一直保留到春天。在今天的照片中，我们看到一些驯鹿在阿拉斯加中南部穿越苏西特纳河。

阿拉斯加有32个不同的驯鹿群。今天的北美驯鹿很可能是Nelchina鹿群的成员，它们在塔基特纳山脉、楚加赫山脉、朗格尔山脉和阿拉斯加山脉环绕的高盆地中漫游，占地约20000平方英里。Nelchina驯鹿群是阿拉斯加驯鹿中研究和认识最多的驯鹿群之一，部分原因是它们的分布范围相对接近该州的主要人口中心。数百年来，牧群一直为阿拉斯加人提供食物，通过仔细监测狩猎法规来维持种群数量。但是驯鹿的数量可能会随着食物的供应和天气的恶劣程度而在一年到另一年之间波动。