There are at least five different groups in the nightjar family seen in North America including the whip-poor-will, Chuck-will's-widow and the nighthawks. The nine bird species in this group are the Eastern Whip-poor-will, Mexican Whip-poor-will, Chuck-will's-widow and Common Nighthawk.
The nightjars can be identified by their calls which are different from one another. These calls usually start just before total darkness and carry on into the night. All nightjars are insect-eating birds and they catch most bugs on the fly.