Intense prospecting movements of failed breeders nesting in an unsuccessful breeding subcolony

Prospecting for a future breeding site may help individuals decide whether to disperse and where to settle. However, little is known about it because of methodological constraints limiting the acquisition of data at fine spatial and temporal resolutions, especially for individuals that have failed breeding. Using recently developed solar-powered GPS-UHF not requiring the recapture of individuals, we tracked failed breeding black-legged kittiwakes, Rissa tridactyla, nesting in a failed subcolony of a large Norwegian colony from the end of incubation and across the chick-rearing period. As predicted, their movement patterns differed significantly from those of successfully breeding birds tracked simultaneously in a nearby successful subcolony. After 1 week of tracking, all failed breeders rapidly abandoned their nesting cliff and males and females simultaneously increased prospecting visits to other parts of their nesting colony and to neighbouring kittiwake colonies situated 40-50 km away. Conversely, none of the successful breeders prospected over the same period. Our results provide new insights on prospecting movements linked to potential dispersal decisions after breeding failure. They suggest that males and females have similar temporal but different spatial prospecting patterns, possibly due to different costs associated with prospecting and dispersal decisions. They also highlight the need to track more comprehensively the movements linked with breeding habitat selection and dispersal in contrasting environmental conditions to better understand the complex behavioural responses of individuals to breeding failure and their consequences for the spatial dynamics of populations.