Oceanic navigation in Cory's shearwaters: evidence for a crucial role of olfactory cues for homing after displacement

Abstract

SUMMARYPelagic birds, which wander in the open sea most of the year and often nest on small remote oceanic islands, are able to pinpoint their breeding colony even within an apparently featureless environment, such as the open ocean. The mechanisms underlying their surprising navigational performance are still unknown. In order to investigate the nature of the cues exploited for oceanic navigation, Cory's shearwaters, Calonectris borealis, nesting in the Azores were displaced and released in open ocean at about 800km from their colony, after being subjected to sensory manipulation. While magnetically disturbed shearwaters showed unaltered navigational performance and behaved similarly to unmanipulated control birds, the shearwaters deprived of their sense of smell were dramatically impaired in orientation and homing. Our data show that seabirds use olfactory cues not only to find their food but also to navigate over vast distances in the ocean. Supplementary material available online at

Key Questions in Marine Megafauna Movement Ecology

“…However, tracking animals can potentially reveal information about their navigational ability. At-sea experiments have been performed, such as temporarily attaching magnets or making animals anosmic and then tracking individuals [91], although typically inferences of navigational cues are made from animals behaving naturally. Across both marine birds and sea turtles, the directed approach to islands from downwind suggests the use of wind-borne odours in island and/or prey finding [92].…”

Visual orientation by the crown-of-thorns starfish (Acanthaster planci)

“…For long-range detection, animals have to rely on another sense, which would likely be olfaction. Successful longdistance navigation by means of olfaction has been found in birds (Gagliardo et al 2013), fish (Keefer and Caudill 2013) and crabs (Weissburg and Zimmer-Faust 1994). Although olfaction is a well-developed sense in many marine benthic invertebrates, it is much less accurate as a directional homing cue in the presence of boundary layer turbulence (Weissburg and Zimmer-Faust 1993), which can be found close to large structures like coral reefs.…”

Olfactory foraging in temperate waters: Sensitivity to dimethylsulfide by shearwaters in the Atlantic Ocean and Mediterranean Sea

“…However, this idea lacks empirical validation and the potential role of DMS in seabird navigation beyond foraging remains unknown. Recently, it has been experimentally shown that Cory's shearwaters need olfaction to navigate over long distances (Gagliardo et al, 2013), but the chemical cues used in this navigation process have not yet been elucidated. Experiments that directly test the use of DMS as a cue for long distance navigation are therefore crucial.…”