SUSTAINED FAST TRAVEL BY A GRAY-HEADED ALBATROSS (THALASSARCHE CHRYSOSTOMA) RIDING AN ANTARCTIC STORM

Auk, The, Oct 2004 by Catry, Paulo, Phillips, Richard A, Croxall, John P

ABSTRACT.-

A Gray-headed Albatross (Thalassarche chrysostoma) was recorded traveling, in the course of a foraging trip, at a minimum average ground speed of >110 km h^sup -1^ for ~9 h with virtually no rest. After taking into account the sinuosity of albatross flight, actual mean ground speed was predicted to be ≥127 km h^sup -1^, achieved in association with high tailwinds during an Antarctic storm. Despite its high speed and the storminess of the sea, the albatross still managed to successfully locate and capture prey at a rate comparable to that achieved under less extreme conditions. This individual's performance suggests that albatrosses have the capacity to maintain positive energy budgets while quickly covering long distances and taking advantage of the strong winds that are frequent in the Southern Ocean. Received 3 November 2003, accepted 13 May 2004.

RESUMEN.-Se registró un albatros Thalassarche chrysostoma viajando en el curso de un desplazamiento de forrajeo a una velocidad con respecto al suelo minima promedio de más de 110 km h^sup -1^ durante ~9 h virtualmente sin descanso. Luego de tener en cuenta la sinuosidad del vuelo del albatros, se predijo que la velocidad promedio con respecto al suelo sería de 127 km h^sup -1^, alcanzada en asociación con vientos de cola de altitud durante una tormenta del Antártico. A pesar de su alta velocidad y de la tormenta, el albatros aún logró encontrar y capturar exitosamente presas a una tasa comparable a aquella alcanzada bajo condiciones menos extremas. El desempeño de este individuo sugiere que los albatros tienen la capacidad de mantener presupuestos energéticos positivos mientras cubren grandes distancias rápidamente y aprovechan los vientos fuertes que se presentan con frecuencia en el Océano Sur.

AS A GROUP, birds are unique, in that many species regularly travel long distances at comparatively high speeds, to take advantage of favorable conditions in widely separated areas. Recent developments in tracking technologies have allowed a progressively greater appreciation of (1) how remarkable such performances are, (2) their constraints and limits, and (3) associated implications for the evolution of migration and life-history strategies (e.g. Spear and Ainley 1997, Berthold 2001, Hedenström 2002). Recent studies of large albatrosses have highlighted an outstanding ability to cover vast areas of the ocean at low energetic cost and at considerable speed (Weimerskirch et al. 2000, 2002). We document what may be the fastest medium- to long-distance travel bout ever recorded for a bird and show that extreme speeds (in this case, by a small albatross species) can be achieved without compromising the capacity for successful foraging while in transit.

METHODS

Observations described here were made during a study of foraging behavior of Gray-headed Albatrosses (Thalassarchc chrysostoma) nesting on Bird Island, South Georgia (54°00'S, 38°03'W; Fig. 1), in February and March 2003. Four Gray-headed Albatrosses were captured, just after feeding their chicks and before they departed to sea, and fitted with several devices to study their movements and behavior. Satellite transmitters (PTT 100; Microwave Telemetry, Columbia, Maryland) weighing 30 g were attached with adhesive tape to the mantle feathers (see Wilson et al. [2002], Phillips et al. [2003], and Catry et al. [2004] for more details on the devices and their attachment and success). Global positioning system (GPS) locations were provided by the Argos satellite system (CLS Argos, Toulouse, France). Birds were also fitted with wet-dry activity data-loggers (Francis Scientific Instruments, Cambridge, United Kingdom) that recorded, every 10 s, whether they were on the sea or in flight. Data-loggers were attached to a plastic band fitted to the tarsus (total mass, including band, 23 g). In addition, birds were fitted with stomach-temperature loggers (Earth and Ocean Technologies, Kiel, Germany) that weighed 42 g (including the anchoring spring) and incorporated a temperature sensor with a relative resolution of 0.1°C, inside a cylindrical titanium housing 99 mm tall and 19 mm in diameter. The anchoring spring hinders the regurgitation of the probe while the bird is at sea (see Wilson and Kierspel 1998 for more details). Loggers record temperature changes in the proventriculus, allowing the researcher to link sudden drops in temperature to ingestion of cold prey (Wilson et al. 1992). Housings were specifically designed to be large enough to sample and integrate the temperature over most of the stomach volume and not become covered by food after ingestion of only a few prey (Wilson et al. 1995). Stomach temperature was recorded and logged every 20 s.

Data from stomach loggers were analyzed using the program FEEDINT (Jensen Software Systems, Laboe, Germany), following Wilson et al. (1992, 1995). Calibrations to allow estimation of mass of ingested prey items were performed on three temporarily captive Gray-headed Albatrosses on Bird Island (Catry et al. 2004). Captive birds were fed several meals of varying mass and composition. Effects on profiles of variation in stomach temperature were assessed quantitatively, so that a relationship between stomach-temperature drop and meal mass could be established.