1971/10/01 by G. L. Kooyman, Wayne Campbell · 5 citations
Environmental Science · #Avian ecology and behavior #Zoology #Emperor #Biology #Ecology
paper · doi:10.2307/4083837
openalex publication_date 1971/10/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/19
ONE of the most unexpected discoveries in the avian world was the breeding of Emperor Penguins during the antarctic winter night (Wilson, 1905: 488).The large size of the chick at fledging and the time required for this development forces the Emperor Penguin to lay its single egg in late May and June (Stonehouse, 1953; Prdvost, 1961) and incubate it through the antarctic night.The rookeries are established on fast sea ice, no formal nest is built, and the adult male incubates the egg in his brood pouch supported on his feet.The newly hatched chick is similarly maintained.Fledging does not occur until late December, and from March through April, depending on the latitude, the birds are again returning to the rookeries to form pairs and breed.Because of these reproductive commitments no other bird or mammal species is so obligated to remain in close proximity to the antarctic continent and the fast sea ice that borders its shores.This means that Emperor Penguins not only dive and feed during winter darkness, as other antarctic penguins do, but at times must do so in heavy pack ice and possibly have to do so even under fast ice, conditions that other penguins seldom, if ever, encounter.These features plus the fact that this species is the largest of diving birds make information about such diving capacities as submersion durations, depth, and swimming speed of especial interest. MATERIALS AND METHODSWe were able to study and measure dives of birds in both natural and experimental conditions.Observations on natural dive patterns and group diving behavior were obtained at Cape Royds in 1967, in the icebreaker channel between Cape Royds and Cape Armitage in 1967, and near the rookery at Cape Crozier in 1968 and 1969 (Figures 1 and2).The usual method was to watch the birds' surface behavior from the edge of the ice and to time their dives.On three different occasions it was possible 1) to study their underwater behavior by lying at the ice edge and watching them dive below us, 2) to observe them while diving with scuba, and 3) in 1969 at Cape Crozier to suture small (4.5 g) capillary Teflon depth-recorders superficially to the back of the necks of birds grouped at the edge of the ice.These birds later entered the water for what appeared to be feeding dives; 2 to 3 hours after attaching the depth tubes the birds were recaptured and the recorders removed.The depth-recorders function on the same principle as those developed by Lord Kelvin in 1878 except the capillary tube is made of Teflon rather than glass (Fryer, 1958).Essentially it is a 61-cm coil of tubing, sealed at one end and coated on the inside with a water soluble dye that leaves a ring at maximum compression.Experimental dives were conducted several miles offshore and northwest of Cape Armitage at a station that consisted of a heated hut over a man-made hole in annual sea ice.These experiments were conducted during three different austral summers,