Penguins are sensitive indicators of the Antarctic climate and of the environmental parameters that limit their presence and distribution. Paleoenvironmental data, obtained from the study of abandoned penguin rookeries (Pygoscelis adeliae) along the Victoria Land coast in Antarctica, indicate a 14C date of 11-13 ka for the oldest abandoned rookery and supply new information about the timing of glacier retreat in southern Victoria Land after the last glacial maximum. The continuous presence of the Adelie penguins is documented from 7 ka. According to our data, the limiting factors that control the presence of penguins along the coast of Victoria Land changed during the Holocene. Whereas several colonies were occupied for very long periods, other sites were used for more or less extended periods and then abandoned. The greatest diffusion ofrookeries occurred between 3 and 4 ka, a period of particularly favorable environmental conditions that has never been repeated. It was followed by a sudden decrease in the number of penguin rookeries shortly after 3 ka. This event has been attributed to an increase of the sea-ice extension and may have been correlated to a worldwide phase ofclimate change near the Subboreal-Subatlantic boundary. A minor phase of penguin reoccupation occurred locally in the eighth to fourteenth centuries (A.D.). Because the presence and number of penguins reflect the state of health of the Antarctic marine ecosystem, it is important to evaluate the variations in their distribution in the past, in the absence of human-induced changes. Considerable information about deglaciation following the last glacial maximum has come from the remains of marine birds along the Antarctic coast. Ornithogenic soils are common, and they show that most of the coastal ice-free areas have been used as penguin rookeries. At abandoned sites a layer of well-sorted pebbles, used by the penguins to build nests, hide relict ornithogenic soils, which provide daltable remains such as bones, feathers, egg fragments, and guano. Dates from several sites document the occupation of rookeries during the past 11 ka.
|Autori:||Baroni C; Orombelli G|
|Titolo:||Abandoned penguin rookeries as Holocene palaeoclimatic indicators in Antarctica|
|Anno del prodotto:||1994|
|Digital Object Identifier (DOI):||10.1130/0091-7613(1994)022<0023:APRAHP>2.3.CO;2|
|Appare nelle tipologie:||1.1 Articolo in rivista|