Mammals require water. When you are in a desert, water is limited. So, a major stream like the Green River is bound to attract mammals. The floodplain, too, provides critical food and habitat for the mammals. The vegetation is lusher, providing both a food source and cover for concealment. And the smallest of mammals seeking food and water are fed on by larger mammals. All of this leads to increased activity as you get closer to a water source.
Spending time along the river offers great opportunities for wildlife viewing and photography. But patience is still required. Afterall, humans are considered a threat to many mammals.
River Otters thrive along a river system. In fact, otters generally forage in the river itself, eating aquatic organisms such as fish, crayfish, frogs, turtles, and insects. I have even seen them feed on Brown Pelicans, after diving underneath the pelican and grabbing it from below.
The Red Fox is a predator, feeding on smaller mammals. While water is critical, the lush vegetation growing in the floodplain provides cover and food for the fox and its prey, such as rodents.
Porcupines feed on inner tree bark, twigs, and leaves. Trees can be found along the floodplain of the Green River. So, the best place to find Porcupines in a desert is near water, where trees can survive.
Water is essential for life. A river in the desert is a magnet for mammals. A quick glance over the river bank may not reveal much. But if you spend time along the river and watch closely, you are bound to see an assortment of mammals sooner or later.