Table 1.

Descriptions of measured behaviors

Behavior	Description
Pairing
Clumping*	Male and female perch in physical contact, facing the same direction
Individual in proximity of another*	Male or female moves to perch less than a body width apart; they face the same direction
Preening*	One individual cleans another's feathers with beak
Reproductive
Tail quiver	Rapid back and movement of the tail. In the female often associated with a bowed position on the perch, but also may be performed by males following copulation
Attempted mount	Male perches at least briefly on the back of the female, but no cloacal contact is observed
Copulation	Male perches on the back of the female and cloacal contact is observed
Beak wipe	Beak is moved back and forth in a rhythmic fashion along the perch
Other
Directed singing*	Male produces song facing the female
Undirected singing*	Male produces the song, but is not facing the female
Beak fencing	Male and female swipe beaks with each other, can be an aggressive behavior
Approach	Direct movement toward the other individual with an upright posture (often followed by clumping or courtship behavior)

Frequencies were assessed for all; durations were also measured for the behaviors with an asterisk.