Circling behavior is thought to serve as a signal to other condors in the area, guiding them to potential food sources. Condors apparently depend on visual rather than olfactory cues to locate food. Having to face changes in food availability, condors have been documented not feeding for a periods up to 14 days. They have a remarkable ability to soar on thermals, or currents of warm air that provide lift. This allows them to fly for a considerable distance without even flapping.
Condors roost in tall snags or on cliff faces to elude terrestrial predators.
Roosts may also serve a social function, as it is common for 2 or more condors to roost together and leave a roost together. Depending upon weather conditions and the hunger of a bird, a California condor may spend most of its time perched on a roost. Although the information regarding California condor mortality is inconclusive, there is evidence to suggest that two anthropogenic factors, lead poisoning and shooting, have contributed disproportionately to the decline of the species in recent years. Although publicity associated with the condor recovery program has doubtless reduced the likelihood of condors being shot, one person was arrested as recently as July 1992 for shooting at a California condor that was part of a reintroduction program. High lead levels, presumably obtained from the ingestion of fragments of lead bullets in shot mammal carcasses, may be a pervasive problem throughout the historical foraging range of the California condor.