The earth’s environment is changing at an unprecedented rate. Climate change, habitat fragmentation, human-wildlife interactions, the emergence of new diseases; all these factors are putting tremendous pressure on both terrestrial and marine ecosystems. The effects of global change are even stronger in what used to be pristine ecosystems such as polar ecosystems of high latitude, where climate forcing, ecotourism and limited breeding habitats increase the stress to which are subjected animal populations, particularly seabirds. Understanding to what extent seabird populations are resilient to current changes requires a dual approach. On one hand, demographic monitoring of seabird colonies enables critical insights into the mechanisms affecting colony performance, from changes in oceanographic processes to the availability and suitability of marine resources on which seabirds rely to thrive. On the other hand, detailed knowledge of individual seabirds’ physiological adaptations (and their limitations) to cope with their unique environments (a life shared between periods at sea and on-land) is needed to understand and predict if, and to what, extent individuals and populations will be able to cope (or not) with environmental change. The ECONERGY polar project has a long history in understanding the intricacies of seabird physiology and the extent to which physiological responses provide adaptive responses to the environment (https://ipev119.wixsite.com/econergie119). It has mostly focused on king penguins (Aptenodytes patagonicus) as a study model, and over the years, has shed critical insights on the behavioural and physiological mechanisms allowing seabirds to cope with the numerous environmental pressures they are subject to, including: (i) long-term fasting, (ii) the alternation between physical inactivity on-land and intense physical activity at sea, and (iii) exposure to parasites, aggressive conspecifics and predators on-land. It has further allowed understanding (iv) the specific quality features that individual birds use to carefully choose their partners, and (v) the physiological mechanisms allowing birds to compromise between reproduction and self-preservation in order to survive. Using a multi-disciplinary approach, it has focused primarily on physiological, energetic, behavioural, and evolutionary aspects of reproduction in adults, and on the extraordinary long growth period and the irregular feeding rates of chicks during the winter. Owing to the impetus of novel members, the current project renewal application marks a break with previous cycles, while building on the fundamental strengths and data collected by the ECONERGY over the years. It proposes to use the knowledge gained from our strong expertise working on the ecophysiology of king penguins to start a long-term physiological observatory of how king penguins cope with environmental changes. To do so, it will build upon data collected in the framework of various experiments since 2011, and complement this data with the yearly monitoring of a representative sample of penguins breeding in different colonial and seasonal conditions. This will allow studying inter- and intra-annual variability in how birds physiologically respond (in terms of energetics and stress) to on-land changes in microhabitat climate, colonial, parasite and predation conditions – over a period of at least 14 years (2011-2025). It proposes to use minimally invasive methodologies to go even further in understanding the energetic and stress responses of those seabirds – and the plasticity of such responses – to rapidly changing environments. Notably, through a combination of experimental, modelling, mitochondrial and proteomic approaches, we will study how birds cope with recurring heat waves on land, how they cope with predation pressure throughout the year, how birds are affected by human disturbance, and how individual quality may determine the inter-related performance of seabirds both on-land and at sea. Using carefully thought long-term data sampling designs combined with advanced statistical modelling techniques we will assess the respective contribution of different exogenous sources of environmental pressures (predation, climate, parasitism, human disturbance) on bird stress phenotype at various stages of the on-land breeding cycle, allowing to understand to which stressors penguins are the most sensitive and when birds are more susceptible to environmental stress. Finally, we will endeavour collaboratively with partners from other polar projects (131, 394, 1151), and research institutes (UK, Finland) to build cross-referenced long-term data bases, allowing a more thorough and precise quantification of the threats that king penguins face in the foreseeable future. The data collected will also serve common purposes, for instance via widespread collaborations with members of the Zone Atelier Antarctique et Terres Australes with which we aim to build a LoRa-connected network (ZATA project WiSeNet 1258) of meteorological stations on the coast line of the Crozet “Ile de la Possession”.