The Western Antarctica Peninsula and Scotia Sea ecosystems appear to be driven by complex links between climatic variables, primary productivity, krill and avian predators. There are several studies reporting statistical relationships between climate, krill and penguins population size. The Adélie (Pygoscelis adeliae). Chinstrap (P. antarctica) and Gentoo (P. papua) penguins appear to be influenced by the inter-annual variability in the sea-ice extent and krill biomass. In this paper we developed simple conceptual models for decipher the role of climate and krill fluctuations on the population dynamics of these three pygoscelid penguin species inhabiting the Antarctic Peninsula region. Our results suggest that the relevant processes underlying the population dynamics of these penguin species at King George Island (Antarctic Peninsula) are intra-specific competition and the combined effects of krill abundance and sea-ice cover. Our results using population theoretical based models appears to supports the idea that global warming represent a major driver of avian predator populations and its major prey at WAP ecosystem. At our study site, penguins showed species-specific responses to climate change. Chinstrap penguins were only influenced by krill abundance. The contrasting population trends of Adelié and Gentoo penguins appear to be better explained by the “sea-ice hypothesis”. We think that proper population dynamic modelling and theory are essential for deciphering and proposing ecological mechanisms underlying the dynamics of these penguin populations.