Copulation behaviour of the Black KiteMilvus migransin Nagasaki Peninsula

To determine whether or not male Black Kite behaviour increases his chance of paternity, the copulation behaviour of 4 pairs was studied in Nagasaki Peninsula in 1991 and 1992. Of 246 within-pair copulation attempts observed, 224 (91%) resulted in cloacal contact. The majority of copulation failures was attributed to refusal of the female, indicating that the female is capable of controlling copulation. Successful copulations were frequent from about 20 days prior to egg-laying until 1 day after laying. During this frequent copulation period, copulations occurred most often in the morning. From approximately 20 days prior to egg-laying onwards, the female Black Kite depended entirely on food delivered by her partner. There was no relationship between courtship feeding and copulation; that is, presentation of food to the female by her partner was not a prerequisite for copulation. Most of the copulations occurred soon after the male returned to the nesting site, suggesting that the male tries to ensure his paternity. Furthermore, the following predictions of the paternity assurance hypothesis were supported: (1) frequent intrusions into the nesting site by other males, and (2) intense aggression against intruders by the pair male compared with the pair female. Thus, it appeared that the male Black Kite tries to improve his likelihood of paternity.