Abstract: This study examines the possibility that metabolic or endocrinal factors initiate fledging in the king penguin, a semi-altricial seabird species breeding a single chick on the ground. Chick fledging (departure to sea) occurred 5d after completion of the molt. It was preceded by a 16d fasting period and by a 7-fold increase in locomotor activity. From the measurement of the plasma concentration of metabolites and of glucagon and insulin, pre-fledging king penguin chicks were found to adapt to fasting in a classical way, i.e. by sparing body protein and mobilizing fat stores. At fledging, chicks were in phase II of fasting and their departure to sea was not stimulated by reaching critical energy depletion (phase III), in contrast to that which has been reported in breeding-fasting adults. The plasma level of corticosterone remained unchanged throughout the whole pre-fledging period, providing no support for a role of this stress-hormone in the facilitation of fledging. Thus, king penguin fledglings did not appear to be environmentally or nutritionally stressed. The plasma levels of thyroid hormones were elevated during the pre-fledging molt, in accordance with their key role in molt control in adult penguins. These levels declined by the time of the molt end, the plasma level of T4 thereafter being directly related to the time left before fledging. These results do not support the view that chronically elevated levels of thyroid hormones are required for the energy-demanding transition between being ashore and in cold water, but they suggest that the maintenance of high T4 levels may delay fledging.

Abstract: AGU Geophysical Monograph Series” 149, ''Continent-Ocean interactions within the East Asian Marginal Seas '', Edited by P. Cliff
Four independent arguments suggest that the Ryukyu subduction zone extended from Japan to southwest Taiwan (118°E) from the late Cretaceous to early Miocene (17-18 Ma): i) An analysis of the structure and timing of rifting in the basins of the East Asia continental shelf and west of Taiwan shows that they are located within four belts parallel to the mainland Chinese shoreline, which becomes younger oceanward since early Tertiary. Ridges with volcanic products are present between these belts. We interpret these basins and associated ridges as relict backarc basins and arcs of the Ryukyu subduction system. ii) Subsidence curves across west Taiwan Basins show that rifting ceased 17-18 Ma. iii) A new shear wave velocity model suggests that the Ryukyu slab extended in the past southwest of Taiwan, beneath the northern China Sea margin. iv) A deep seismic line shot across the north-eastern South China Sea margin also suggests that this margin was active in the past. We conclude that about 15-20 Ma, the southwestern extremity of the Ryukyu subduction zone jumped from 118°E (southwest of the Tainan Basin) to 126°E (where the present-day trend of the Ryukyu subduction zone changes direction). Since that time, the southwestern extremity of the Ryukyu subduction zone continuously moved westwards to its present-day location at 122°E. Since the beginning of formation of proto-Taiwan during late Miocene (9 Ma), the subducting PH Sea plate moved continuously through time in a N307° direction at 5.6 cm/yr with respect to EU, tearing the EU plate.