Explanation: Male and female Common Nighthawks use a vocal “peent” call in flight, both during migration and on the breeding grounds. Male Common Nighthawks also make a non-vocal “boom” sound that is produced by air rushing through feathers in a sudden downward flexing of wings during a steep aerial dive. These boom displays are generally only associated with mating and territorial displays and do not occur outside of the breeding season. The peent call by itself provides no indication of breeding, but it is the more common way that this species is identified in the field. The boom sound is generally used to define the boundaries of a breeding territory and when performed repeatedly (e.g., greater than 3 times in a 5-minute period) can indicate a nest.             

Summary: Birds detected visually or heard using the peent call can be assigned a possible breeding evidence code “H”, when detected in what appears to be suitable breeding habitat (e.g., logged or burned areas, rock outcrops, clearings, etc.). When booms are detected, but are occurring in the air or not frequently happening close to the ground, the probable breeding code “D”, which is indicative of courtship or a breeding display, can be used. If booms are happening frequently near the same location on the ground, the probable breeding code “V” can be used to indicate a bird visiting a probable nest site. All breeding codes only apply during safe breeding dates.