Caribou crossing the Susitna River during the autumn rut

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.