TITLE:   Increases in Antracctic penguin populations: reduced competition
	 with whales or a loss of sea ice due to environmetnal warming?
AUTHOR:  WR Fraser, WZ Trivelpiece, DG Ainley, SG Trivelpiece
Polar Biology 11:525-531, 1992
Palmer LTER Contribution #35

A central tenet of Antarctic ecology suggests that increases in Chinstrap 
Penguin (Pygoscelis antarctica) populations during the last four decades 
resulted from an increase in prey availability brought on by the decrease in 
baleen whale stocks.  We question this tenet and present evidence to support 
the hypothesis that these increases are due to a gradual decrease in the 
frequency of cold years with extensive winter sea ice cover resulting from 
environmental warming.  Supporting data were derived from one of the the 
first, major multidisciplinary winter expedition to the Scotia and Weddell 
seas; recent satellite images of ocean ice cover; and the analysis of long-term
surface temperature records and penguin demography.  Our observations 
indicate there is a need to pay close attention to environmental data in the 
management of Southern Ocean resources given the complexity of relating 
biological changes to ecological perturbations.