Nervous, and submissive to most other hummingbirds (Parker and O'Neill 1980, Fjeldså and Krabbe 1990, Fjeldså 1999). When feeding aerially, hovers with an almost vertical body, frequently opening and closing tail, exposing much white. Oreonympha also may also cling to flowers while feeding, occasionally holding its wings open while doing so (Fjeldså and Krabbe 1990).
Undescribed; presumably is polygynous, as are most if not all species of hummingbirds (Schuchmann 1999: 509).
Social and interspecific behavior
Bearded Mountaineer usually is solitary.
This species is subordinate in the flower-access hierarchy of high, dry, valley hummingbirds (Parker and O'Neill 1980, Fjeldså and Krabbe 1990). Oreonympha is often sympatric with Giant Hummingbird (Patagona gigas), Sparkling Violetear (Colibri coruscans), and Green-tailed Trainbearer (Lesbia nuna), of which it is dominant over only much smaller trainbearer (Parker and O'Neill 1980).
No reports of predation on Bearded Mountaineer?