Telemetry Studies of the Internal Body Temperatures of Adélie and Emperor Penguins at Cape Crozier, Ross Island, Antarctica

HO•rEOT•ER•4S of both tropical and polar regions are able to regulate internal temperatures only within certain environmental imits. Extension of these limits is possible only by physiological and/or behavioral adaptations that are often more conspicuous in species of very cold environments. Cape Crozier (Ross Island, Antarctica) is the extreme southern locality where comparative field studies of the Addlie (Pygoscelis adeliae) and Emperor (Aptenodytes forsteri) Penguins are possible. With emphasis on investigation of behavioral adaptations in temperature regulation, the internal body temperature was monitored and its variation studied during two austral summers of field studies, 1965-66 (Sladen et al., 1966) and 1966-67 (Boyd et al., 1967). Previous investigators (Eklund, 1942; Goldsmith and Sladen, 1961; Prdvost, 1961; Prdvost and Sapin-Jaloustre, 1964; Mougin, 1966) had determined internal temperature values for these species, but our data present values of abdominal cavity temperatures monitored continuously during selected states of behavior. The study was aimed at further development of a biotelemetry system to monitor the physiology and behavior of unrestrained birds. In particular, such a technique might be employed to study the winter-nesting Emperor Penguins in 24-hour darkness and severe weather conditions, as they move around while incubating or brooding on the sea ice of the rookery. Field investigations were carried out at the Addlie Penguin rookery (77 ø 26' S, 169 ø 18' E), 8 km northwest of Cape Crozier and 7 km west of the Emperor rookery. About 150,000 breeding pairs of Addlie Penguins are present in the main rookery in contrast to the 1,000 to 2,000 pairs of Emperors on the nearby sea ice. The Addlie rookery is part of the large ice-free area at the eastern tip of Ross Island and benefits from a northern exposure and frequent winds, keeping snow cover at a minimum. Nearby Mount Terror (altitude 3,230 m) and the lowered albedo of the dark exposed ground (in contrast to that of nearby ice fields and the Ross Ice Shelf) considerably affect the climate of the rookery. Our 1966 67 weather observations (Figure 1) were taken from the Jamesway hut (134 m elevation). Janetschek (1967: 215) gives a summary of the metereological conditions of Ross Island. Most field work was done at a coastal site (27 m elevation) from a hut