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Avian ecological energetics, Ship Island following trans-gulf migration. Con- p. 161-220. In D. S. Farner,J. R. King, and K. C. dor 93:869-883. Parks [eds.], Avian biology. Vol. 7. Academic LIGON, J. D. 1974. Green cones of the pifion pine Press, New York. The Condor 100:376-381 0 The Cooper Omlthological Society 1998 SATELLITE TRACKING OF MAGELLANIC PENGUIN MIGRATION’ DAVID L. STOKESAND F! DEE BOERSMA Department of Zoology, Box 351800, University of Washington, Seattle, WA 9819.5, e-mail: [email protected] LLOYD S. DAVIS Department of Zoology, University of Otago, P.O. Box 56, Dunedin, New Zealand Abstract. We tracked four male Magellanic Pen- Argentina where they had bred and molted, all four guins (Spheniscus magellanicus) from the beginningof birds traveled northeastalong the coast at speedscon- their winter migration for periods ranging from three sistent with sighting and band-return data which sug- to six weeks. Upon leaving the colony at PuntaTombo, gest a round-trip winter migration in this speciesof up to several thousandkilometers. Three of the birds fol- lowed a similar route, moved at approximately the ’ ’ Received 15 May 1997. Accepted 6 January 1998. same rate, and were still moving northeastwardat a SHORT COMMUNICATIONS 377 distance of over 800 km from the colony when signals devices (attached to males #l-3) were 0.25-watt mi- ceased. The fourth bird departed from the northeast croprocessor-controlled satellite-linked time-depth re- route at approximately 306 km into its trip and re- corder/transmitters manufactured by Wildlife Comput- mained in a large bav for at least 29 davs. when the ers Inc. (Redmond. WA) using Telonics ST-10 trans- last signal was”rece&ed. Initially, the birds traveled mitters. These devices, including waterproof epoxy rapidly and made few deep dives. Later, their rate of housing, each weighed approximately 155 g, and had travel slowed, their paths became more erratic, and a cross-sectional area of 13.5 cm2, approximately 7- they made more deep dives, all indications of probable 8% of the cross-sectional area of a male Magellanic foraging. This suggests that location of the penguin Penguin. The fourth device (attached to male #4) was migration route and rate of travel along it may be de- manufactured by Sirtrack Ltd. (Havelock North, New termined by seasonal movement of prey. As all birds Zealand) and also used a Telonics ST-10 transmitter were within 250 km of shore for the entire period in packed in an epoxy housing. It weighed 96 g and had which signals were received, our results underscore the a cross-sectional area of 6.5 cm2. We used fast-setting importance of controlling pollution associated with pe- epoxy to attach the devices to the feathers in the center troleum transport along the coast of Argentina, cur- of the penguin’s lower back. All devices had sloped rently a major source of Magellanic Penguin mortality. leading and trailing faces and were positioned poste- rior to the line of maximum girth to minimize drag Key words: Magellanic Penguin, migration, pen- (Bannasch et al. 1994). guins, satellite telemetry, Spheniscus magellanicus. We programmed the Wildlife Computer devices to transmit at 45-set intervals every other day, primarily As with other penguins, little is known of Magellanic during the night-time hours most likely to coincide Penguins’ (Spheniscus magellanicus) activities during with satellite passes. At night, Magellanic Penguins the nonbreeding season. After chicks fledge, breeding tend to rest at the ocean surface and hence the trans- adults undergo a synchronous molt in March and April mitter signal is less likely to be broken due to sub- and then leave the breeding colony, not to return until merging of the antenna (P D. Boersma, unpubl. data). the following September or October. Their where- The Sirtrack device was pre-set to transmit at 60.set abouts during this 5-to-6 month period have been in- intervals for 6 hr every 72 hr. In addition to location, ferred from sightings of unmarked birds as well as the Wildlife Computer devices recorded frequencies of band returns, mostly from dead birds that have washed dives in six depth classes (3-5, 6-10, 11-20, 21-40, ashore. These methods indicate that Magellanic Pen- 41-60. and 61-80 m) for 6-hr oeriods (03:00-09:OO. guins migrate northward in the winter (Daciuk 1977), 09:00~15:00, etc. local time) ea’ch day. ~ in some cases apparently more than 2,000 km (I? D. We received transmissions through the Service AR- Boersma, unpubl. data). However, sightings of un- GOS satellite system. Sixty-one percent (n = 86) of marked birds give no indication of breeding status or locations received (n = 140) were based upon at least colony of origin, and band returns yield imprecise lo- four messages per satellite pass and were accurate to cations of live birds and give little indication of pattern within 1 km (location class 1 or better; ARGOS 1996). of movement or distance from shore of migrating The accuracy of the remainder of locations could not birds. Such information is important for the protection be determined with certainty (ARGOS 1996); however of this species, which is currently declining (Boersma based upon locations received for birds at known po- 1997) primarily due to human activities at sea, chiefly sitions (Stokes and Boersma, in press), locations cal- commercial fishing and oil pollution (Gandini et al. culated from three messages per pass (class 0 and class 1994, Boersma and Stokes 1995). A, n = 45) are sufficiently accurate for the purposes The recent development of a practical technique for of this study (mean error 2 SD = 2.9 2 3.6 km, n = tracking penguins at sea using satellite telemetry has 12). We did not use locations based upon fewer than the potential to improve our understanding of penguin three messages (class B and Z, n = 9). For the pur- migration by providing precise day-to-day monitoring poses of calculating travel speed, we used only loca- of live individuals of known breeding site, sex, age, tions of class 1 or better. Maps of travel routes (Figs. and breeding status. Studies using this-technique (Ker- 1 and 2) were made, and distances and swimming ry et al. 1995, Davis et al. 1996) have documented speeds calculated, using Arc/Info geographic infor- long-distance post-breeding migration in Adelie Pen- mation software (ESRI 1992). Values presented are guins (Pygoscelis adeliae) in the Antarctic and have means ? SD. described the routes followed bv individuals in the ear- ly part of the migration. Here-we report on the first RESULTS use of satellite telemetry to track the migration of a temperate penguin species, the Magellanic Penguin. Upon leaving the colony, all birds initially traveled northeast (Fig.