"(1) The bow-coo. Only males give bow coos under ordinary conditions, however, females long isolated from males may do so irregularly. This is the fastest coo in courting behavior, and is always directed at a particular bird with an accompanying head bow. The feet often alternate in "stamping". Perch coos and nest coos are slower and softer and the nest coo is always accompanied by wing "flipping". Perch coos and nest coos may be given by both sexes.
(2) Billing. The female may put her bill inside the males mouth after squab-like begging movements and be fed token amounts.
(3) Sex crouch. To culminate courtship in mated pairs, the female will squat down, tuck her head in close, and raise her shoulders preparatory to supporting the males feet.
(4) Sex-mount. (Treading) The male repeatedly cranes his neck above the female (which is in a sex crouch). He may sporadically "preen" between wing tips and rump, fluff rump and posterior feathers, then mount the female, both facing the same direction. The tail of the male bends and swings to one side of that of the female, and his wings flutter to maintain balance. Within seconds the male tips backward and the cloaca meet in quick copulation. The "laugh" or challenge note normally is given immediately after copulation by both sexes. (A long isolated pair of females may mount each other.)
(5) Display flight. The male flies upward wing clapping, then glides down.
Certainly, of these sex behavior characters which can allow one to infer sex, the most frequent one is the bow-coo."
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