Communal Roosting of Common Ravens in Southwestern Idaho

From 1983-1987, Common Ravens (Corvus corax) used thirteen communal roosts on a segment of electrical transmission line that runs 597 km from south-central Idaho to south-central Oregon. Up to 2013 ravens were counted at a single roost that spanned approximately six km of transmission line and 15 transmission towers. Most roots were occupied between spring and autumn; one was occupied year-round. Peak numbers of ravens at most roosts and peak numbers of occupied roosts occured during late summer and early autumn. Ravens concentrated on the highest portions of towers when winds exceeded seven km/hr. Ravens arrived at roosts earlier relative to sunset during summer then during spring and fall. Soon after fledging, juvenile and adult ravens left nesting areas and moved as far as 60 km to communal roosts. SOme ravens used more than one communal roost during a year, moving between rossts up to 63 km apart.