Northern flickers (Colaptes auratus) are well known as cavity-nesting birds very adept at excavating their own holes, which are usually in trees (Godfrey 1986, The Birds of Canada. National Museum of Natural Sciences, Ottawa.). There are also records of this species foregoing excavation and nesting in boxes, buildings, stumps, telephone poles, hay stacks, fence posts, wagon hubs, barrels, unused chimneys, and in the nests of other species of birds (Bent 1939, Life Histories of North American Woodpeckers. U.S. National Museum Bulletin 174. Washington, D.C.; Cannings et al. 1987, Birds of the Okanagan Valley, British Columbia. Royal British Columbia Museum, Victoria). However, there are few published data on the roosting behavior of these birds at night (Bent 1939), especially outside of the breeding season when both sexes are known to participate in the incubation of eggs and chicks (Harrison 1984, A Field Guide to the Nests, Eggs and Nestlings of North American Birds. Collins, Toronto). This paper reports observations of unusual night roosting behavior by northern flickers in the Okanogan valley of northern Washington and southern British Columbia. While searching for night roosting bats, we observed flickers on four different nights, roosting under the concrete bridge supporting Highway 97 and spanning the Okanogan River 1 km south of Oroville, Washington (5 km south of the Washington-British Columbia border; Table 1). The underside of the bridge consisted of 45 compartments which resembled open upside down boxes, arranged end to end in a 15 x 3 pattern. Each compartment was approximately 2.5 m wide (making the bridge approximately 7.5 m wide), 4 m long (making the bridge approximately 60 m long) and 1 m deep. The compartments varied from 2-15 m above the ground or water, with the compartments at the north end of the bridge closest to the ground. The middle third of the bridge (i.e., 15 compartments) was above the river, with the north and south thirds spanning the north and south river banks respectively. On each of the four nights when observations were made, 2-4 birds easily identified as flickers by the characteristic spotting on their backs and white rump, roosted in compartments on the underside of the bridge. The flickers always roosted in compartments over the south bank of the river (Table 1) and we never found more than one bird in any compartment at a time. The birds hung in an upright position by their toes on the vertical wall of the compartment and appeared to use small rough edges in the concrete as toeholds. In all cases, the birds roosted within several centimeters of the ceiling with their heads tucked into their breasts. Of 11 observations of birds roosting on the four different nights, 10 birds roosted on the north wall of a compartment whereas only one roosted on a south wall. On each of the four nights that we checked the bridge, observations were continued until at least 1.5 hr after sunset. We examined all compartments for roosting animals. On three of the four nights, big brown (Eptesicus fuscus), little brown (Myotis lucifugus) or Yuma (M. yumanensis) bats were also