Courtship in ospreys centers on food and nest sites. In migratory osprey populations, males and females arrive at the nest site separately, the male often arriving several days earlier than the female. Male ospreys sometimes perform a conspicuous aerial display near the nest site. This display usually occurs during early courtship, and serves to attract their mates and to threaten any intruder.
This courtship dance, often called “sky dance” is a spectacular, wild yo-yoing display of flight. The male impresses the female with his catch and then, after briefly treading air, drops down a hundred feet, before treading air again and then quickly rising.
This video is pretty good, considering it was made with an i-phone.
Once a pair has established a nest, the male begins to deliver food to the female.
During the courtship period the male continually offers food to the female. This behavior continues throughout the breeding cycle, and is critical for pair bond formation and female fidelity. This feeding continues until the young fledge or the nest fails. Generally, females that receive more food are more receptive to mating attempts by the male. Females beg for food from their mates, and occasionally from neighboring males if they are not well fed by their mate. Males may protect their paternity by feeding their mate well. They may also protect their paternity by guarding their mate from other males and copulating frequently when she is most fertile (several days before egg laying).
If the dance is spectacular foreplay, then the sex itself is fast and furious, lasting just a few seconds. Don’t miss the next post.
Courtship feeding has been suggested to function in several ways: to advance laying date by improving female condition, to induce a female to copulate or to allow a female to assess her mate. The role of courtship feeding in Ospreys Pandion haliaetus was investigated in British Columbia, Canada. Courtship feeding rate affected the probability of a pair initiating a clutch. Pairs that laid eggs had higher rates of courtship feeding than pairs that did not lay eggs in both 1991 and 1992. Male courtship feeding rate also correlated negatively with the duration of the courtship period. Experimentally increasing the amount of food available to females prior to egg-laying resulted in a non-significant reduction in the duration of the courtship period. This study found no evidence to support the suggestion that female Ospreys trade copulations for food during the courtship period; only 63 of 385 copulations observed were associated with feeds, and courtship feeding rate did not correlate with the copulation rate of a pair. Male provisioning rates, however, were predictable; courtship feeding rate correlated with both male delivery rate to the nest when chicks were 1–2 weeks old and mean brood growth rate. Female Ospreys therefore may be able to predict the quality of subsequent paternal care using courtship feeding rate. As predicted if optimal hatching asynchrony is dependent on food availability, mean brood growth rate, an indirect measure of male parental care, was negatively correlated with hatching asynchrony. This suggests that female Ospreys may manipulate hatching asynchrony in response to male courtship feeding rate, thereby maximizing the productivity of their brood at predicted food levels.