Copulatory behavior of semi-colonial Montagu's Harriers

The copulatory behavior of the monogamous Montagu's Harrier (Circus pygargu s) was studied between 1992 and 1995 near Madrid, Spain. Copulations starte d around 20 days before laying, and typically stopped at the end of the lay ing period, Copulation frequency peaked just before the start of the laying period, averaging 2.2 copulations day(-1). Females copulated on average 39 times per brood Copulation rates apparently were not related to food provi sioning by males except in the early pre-laying period. At least 5 and up t o 11 (4-8%) of the copulations observed were extra-pair copulations (EPCs), and all occurred within the fertile period. Montagu's Harriers increased t heir copulation rate in situations of increased EPC risk: solitary pairs co pulated for a shorter period of time and at an overall lower frequency, whe reas pairs nesting in clumps showed higher copulation rates with increasing number of neighboring pairs. This increase was most marked during the layi ng period, when there is a higher risk of EPCs producing extra-pair fertili zations.