Ospreys Return (and Mate)

Thursday gave us great weather for a class field trip to the Calgary Zoo.  Having read some reports of returning Ospreys on Albertabird earlier in the week I had one eye on the nesting platform on the east end of the Zoo island.  Sure enough, there was a pair on the platform, although a little too far away to effectively show to my students.  Fortunately, while we were touring the Canadian Wilds area after lunch, the same pair put on a great display soaring over our heads.

Osprey, Pandion haliaetus

After these sightings, I decided to bike out to the nest platform at Crowchild Trail and Memorial Drive.  There was another osprey pair here and I was able to get some photos of this pair mating.  Coincidentally, the theme of our Zoo field trip earlier in the day had been reproductive strategies - the above photo was taken at the whooping crane exhibit just as we were discussing the "cloacal kiss".  This momentary contact between the male and female urogenital openings allows sperm from the male to pass into the female.  To illustrate just how momentary this contact was I've included the camera's timestamps for each image in the sequence below, taken from the pedestrian overpass east of Crowchild Trail.

4:40:15, both birds on nest

4:40:34, Bird on nest takes off and does rapid wide loop around valley

4:40:37, Approach

4:40:38, Landing

4:40:42, getting lined up

4:40:48, "Cloacal Kiss"

4:40:49, Done!

If anyone has any more specific information about Osprey's mating feel free to add it in the comments.  My impression was always that they mate for life but according to Sibley's "Guide to Bird Life and Behaviour" Osprey's may demonstrate polygyny.  In any case they are beautiful raptors and here's a photo of the female (I assume the female is on the bottom?) from the sequence above.  The pair at the zoo have a nestcam which can be found at the Enmax website.