Sand-colored Nighthawk Chordeiles rupestris

In a family in which most species are nocturnal and solitary, the gregarious and partially diurnal Sand-colored Nighthawk is one of the most aberrant of all nightjars. It is distributed throughout the interior of the Amazon basin and is closely tied to open rivers where it can often be found in flocks of up to 200 individuals, perched along sand or gravel bars, beaches or on accumulated driftwood and logs. Along certain stretches of river where aerial insects are particularly abundant, enormous congregations can often be found in the late afternoon, with hundreds of Sand-colored Nightjars streaming in from both upstream and downstream.