Time of day of ovulation by three duck species in subarctic Alaska

I examined variation in ovulation times of Northern Pintails (Anas acuta), American Wigeon (A, americana), and Lesser Scaup (Aythya affinis) breeding in subarctic Alaskan wetlands. Ovulation times and by extension egg-laying times were high ly variable in all three species, with ovulations occurring during all hours of the day. Only Lesser Scaup demonstrated a morning peak in ovulations. within a broad range of ovulation times. Lack of a distinct time of day of ovulation suggests that fitness is not related to egg-layin g time for these species. particularly at subarctic latitudes with nearly p erpetual daylight. Egg-laying interval may have more adaptive significance than egg-laying time for these species. Ovulation intervals were estimated to be approximately 24 hr, which is short relative to the range of interval s documented in birds. despite high energetic and nutritional costs of egg formation in these species. Evidence of approximately 24-hr ovulation inter vals, particularly in the absence of a distinct time of day for egg laying, supports hypotheses that a shortened period of egg production in waterfowl may have selective advantage due to reduction in the period of nest exposu re to predation, earlier hatch dates. reduced hatch asynchrony, or improved viability of early-laid eggs.