Behavioural Processes 61 (2003) 95–100 Homing in pelagic birds: a pilot experiment with white-chinned petrels released in the open sea Simon Benhamou ∗ , Joël Bried, Francesco Bonadonna, Pierre Jouventin CNRS-CEFE, Behavioural Ecology Group, F-34293 Montpellier Cedex 5, France Received 6 August 2002; received in revised form 19 November 2002; accepted 20 November 2002 Abstract During the breeding period white-chinned petrels (Procellaria aequinoctialis) repeatedly perform long foraging trips in the open ocean from their breeding island, and are able to home with an astonishing precision. The orientation mechanisms involved are not yet known. By analogy with those used by desert ants moving in a similarly “featureless” environment, one can hypothesise that petrels may home using path-integration. We displaced 11 white-chinned petrels 725–785 km from their burrows to the open sea, preventing them from using visual and magnetic route-based information. Three birds carried satellite transmitters. Our results showed that they can home rather efficiently in such conditions. © 2002 Elsevier Science B.V. All rights reserved. Keywords: Homing; Navigation; Path-integration; Petrel 1. Introduction Long distance homing in birds has been the sub- ject of intensive research for several decades. The orientation mechanisms involved have been tackled mainly through experiments with homing pigeons (e.g. Wallraff, 2001). Terrestrial environments provide birds with many potential informational sources, making it difficult to disentangle the orientation mechanisms re- ally involved. To address this question in a simplified context, a suitable means consists in studying hom- ing performances of pelagic birds. The open ocean constitutes a kind of “featureless” environment due to the lack of topographic cues, even if there exist some diffuse information sources such as sea surface temperatures and odours (Bonadonna et al., 2002). White-chinned petrels (Procellaria aequinoctialis) are ∗ Corresponding author. E-mail address: benhamou@cefe.cnrs-mop.fr (S. Benhamou). pelagic birds that seem to be particularly suitable for long distance homing studies. During the incubation period, they repeatedly leave their breeding sites on small isolated oceanic islands and fly for several days and nights over several thousands of kilometres above the ocean searching for food at very distant foraging sites (Catard and Weimerskirch, 1999; Weimerskirch et al., 1999). They then usually return to their nests along nearly straight line homing paths. Like breeding petrels, desert ants (Cataglyphis sp.) return to the small target corresponding to their nest with an astonishing precision after a long and sin- uous foraging trip in an apparently featureless envi- ronment (see Wehner, 1998). Desert ants are able to update in memory the direction and distance of their nest by path-integration based on translational infor- mation provided by the optical flow from the ground and rotational information information provided by a sun compass (Wehner et al., 1996). Such an abil- ity to home by path-integration has been shown in 0376-6357/02/$ – see front matter © 2002 Elsevier Science B.V. All rights reserved. PII:S0376-6357(02)00168-7