The ORNITHO-ENDOCRINO research project aims at investigating the consequences of contaminants exposure on maternal effects in two arctic seabirds from Svalbard. The selective deposition of avian maternal hormones could allow females to strategically adjust the phenotype of their offspring to the environmental situation encountered. Less is known however on how females transfer their pollutants to the eggs and how these pollutants could disrupt such adaptive maternal deposition. We wish to: 1) Relate individual variations in migratory migration strategies and foraging behavior (via geolocators and GPS tracking) to contaminants and hormones maternal transfer to the eggs; 2) Explore relationships between contaminants (legacy POPS, PFAS and mercury) and hormones (steroids, glucocorticoids and thyroids) found in the eggs; 3) Assess the consequences of maternal hormones disruption on offspring’s physiology and fitness. The ORNITHO-ENDOCRINO research project will also contribute to the long-term survey of contaminants, migration and foraging areas of Svalbard seabirds, led by the Norwegian Polar Institute (NPI) and the Norwegian Institute for Nature Research (NINA).