Cranes and other wildlife are stressed by many threats such as predation by humans, sickness, and pollution.  Habitat loss, however, is by far the greatest threat.   Sandhill cranes are particularly sensitive to this threat because they have special habitat needs.  They require roosting as well as feeding habitat.  They roost (stay overnight) in shallow wetlands, but they feed in agricultural fields that have been harvested.  Cranes some times feed on graslands, but they prefer corn, rice, alfalfa, or wheat fields.  These fields need to be within a reasonable proximity to roosting sites, which provide a safe harbor for the night.  Some prime examples of crane habitat can be seen at the Cosumnes River Preserve (www.cosumnes.org) and neighboring farm lands.

How much open space do cranes need?

Visitors to the Cosumnes River Preserve are often surprised by how easy it is to view cranes, and may mistakenly conclude that their abundance on the Preserve is an indication of a prosperous and vigorous population.  This may not be the case, as overcrowding generally puts any wild population at increased risk of disease. 
Although it is not known exactly how much land is needed to provide adequate space for a healthy population of cranes, the fact that crowding is already occurring indicates how important it is to focus on preserving open space and remaining crane habitat for future generations of cranes and people.