Here is the approximate nesting cycle for osprey, from the USGS publication Ospreys in the Pacific Northwest:
Arrival at nest sites: 20 March - 15 April
Clutch completion: 13 April - 20 May
Hatching: 21 May - 27 June
First flight of young: 15 July - 21 August
Departure for winter: 20 August - 25 September
