The field studies were carried out on seven species of large size Procellariiforms equipped with the Argos system (satellite transmitters, Platform Terminal Transmitters, 32g PTT100 and 64g Toyocom 2038C, Microwave Telemetry, Columbia, MD, USA) during the same reproductive period (mid-incubation), from three study sites in South Indian Ocean: Crozet (46°26′S; 51°52′E), Kerguelen (49°40′S; 70°15′E) and Amsterdam (37°51′S; 77°31′E) Islands in south Indian Ocean. Deployments were carried out on different bird populations, from Crozet on wandering albatross Diomedea exulans L. (WAc) in 1998 (n = 17 individuals), 1999 (n = 14) and 2000 (n = 9), sooty albatross Phoebetria fusca Hilsenberg (SA) in 1992 (n = 5), 1993 (n = 3) and 1994 (n = 5), light-mantled albatross P. palpebrata Forster (LMA) in 1994 (n = 3) and white-chinned petrel Procellaria aequinoctialis L. (WCP) in 1996 (n = 6); from Kerguelen on wandering albatross (WAk) in 2002 (n = 12) and black-browed albatross Thalassarche melanophrys Temminck (BBA) in 1999 (n = 7); from Amsterdam, Amsterdam albatross D. amsterdamensis Roux et al. (AA) in 1996 (n = 6) and 2000 (n = 9) and Indian yellow-nosed albatross T. carteri Rothschild (YNA) in 2000 (n = 9) and 2002 (n = 17). Signal emission rate was the same for all PTTs (i.e. 90 s). Details about deployments can be found in Weimerskirch (1998), Weimerskirch et al. (1999), Pinaud & Weimerskirch (2002, 2005) and Waugh & Weimerskirch (2003). The satellite transmitter represented 0·5–2% of the mass of birds. In some cases, several trips existed for the same individual, so we used the first one for analysis to avoid pseudoreplication. Gender was determined for WA, AA and YNA only, using morphometric measurements. According to Argos location accuracy class (A, B, 0, 1, 2 and 3, Argos 1996), all class B fixes were removed since their accuracy was low (46 km ± 59, n = 67, calculated with PTTs at a fixed position). Locations were then filtered according to maximum speeds (see Weimerskirch et al. 1993, 2000; for details) obtained from calculations (Pennycuick 1982) and observations (Alerstam, Gudmundsson & Larsson 1993) for each species. After filtering the Argos locations, accuracy was better than 2 km. Position of the sun was calculated at each location, with the civil twilight considered at 6° below the horizon.