Danny Green / Snow monkey (Macaca fuscata) close up with eyes cast down, Nagano, Japan, February

Danny Green / Japanese Macaque (Macaca fuscata) carrying young on back through snow, Nagano, Japan, February

Danny Green / Japanese Macaque (Macaca fuscata) carrying young on back through snow, Nagano, Japan, February

Aflo / Japanese macaque (Macaca fuscata) mother cuddling baby, Yamanouchi, Shimotakai District, Nagano Prefecture, Japan. June.

Mark MacEwen / Japanese macaque (Macaca fuscata) relaxing in hot spring in Jigokudani, Yaenkoen, Nagano, Japan, February.

Mark MacEwen / Japanese macaque (Macaca fuscata) sleeping at hot spring in Jigokudani, Yaenkoen, Nagano, Japan, February.

Diane McAllister / Japanese Macaque (Macaca fuscata) female holding baby close in snow, Jigokudani, Japan.

Diane McAllister / Japanese Macaques (Macaca fuscata) enjoy time soaking and grooming in the hot spring in Jigokudani, Japan.

Diane McAllister / Japanese Macaque (Macaca fuscata) pair rest together on a rock near the river in Jigokudani, Japan.

Diane McAllister / Japanese Macaque (Macaca fuscata) adult with wet snowy head in the hot springs of Jigokudani, Japan.

Diane McAllister / Japanese Macaque (Macaca fuscata) juvenile riding on its mother's back, along snow trail in Jigokudani, Japan.

Diane McAllister / Japanese Macaque (Macaca fuscata) adult in the hot springs of Jigokudani, in the snow, Japan. February