The term 'BIRD GULP DOWN' can be solved by the crossword solution 'SWALLOW'. SWALLOW is a type of bird that belongs to the Hirundinidae family. It is known for its aerial feeding behavior, where it catches insects in mid-air. The SWALLOW has a distinctive forked tail and pointed wings, which help it maneuver quickly in flight. Its diet consists mainly of flying insects, such as flies, moths, and beetles. The SWALLOW is also known for its ability to gulp down large amounts of food in one go.