Area covered by photographic survey over whelping patches on 28 March (blue), and areas covered by reconnaissance flights conducted by aircraft (22 March – 1 April) and helicopter (18 March– 1 April) (green). Ice drift in the Greenland Sea during the period 21 March – 11 April (purple line) and 23 March– 12 May, as observed from two satellite-based GPS beacons deployed on the ice. Øigård et al 2014