With dogs’ breath fogging the 30-below zero air at their knees, 71 Iditarod mushers steamed their way down the frozen Chena River in Fairbanks on March 6. Upstream, just a few miles behind them, 500 ducks were surviving in a one-mile stretch of open water.

With dogs’ breath fogging the 30-below zero air at their knees, 71 Iditarod mushers steamed their way down the frozen Chena River in Fairbanks on March 6. Upstream, just a few miles behind them, 500 ducks were surviving in a one-mile stretch of open water.