Long-term population trends in seven Antarctic seabirds at Pointe Geologie(Terre Adelie) - Human impact compared with environmental change

Antarctic seabird populations have been much studied over the last decades as bioindicators of the nature of variability in the Southern Ocean marine ecosystem, and most attention has been focused on the role of food supply a nd the extent of sea ice. In addition, the rapid spread of tourism and the activities of researchers since the early 1960s have raised questions relat ed to their real and potential impact on bird populations. Our data sets st art in 1952 for several species of Antarctic seabirds and this study docume nts the trends over a 14-year period (1985-1999) in seven species breeding on Pointe Geologie archipelago (Terre Adelie, Antarctica). This is the firs t study where the direct impact of destruction of breeding sites (for build ing of an airstrip) is examined and where such long-term populations trends have been assessed in such a number of Antarctic species at one site. Tren ds from 1985 show that for the whole archipelago and when excluding islands destroyed, Adelie penguins and south polar skuas were the only species to show a significant increase (>3.5% annual change). The others species showe d opposite trends, three increasing slightly (southern fulmars +0.4%, cape petrels +2.3%, snow petrels +0.9%) and two decreasing (emperor penguin -0.9 %, southern giant petrel -3.9%). Three species particularly affected by the destruction of their breeding habitat (Adelie penguin, cape petrel, snow p etrel) showed the capability to restore their populations. The availability of food and nesting sites is discussed in relation to environmental change . Species feeding on krill (Adelie penguins and cape petrels) increased mor e than other species; however, decrease of ice cover can increase availabil ity of nesting sites. The importance of long-term studies is shown when ass essing the role of human activities in Antarctica compared to larger-scale changes.