IN MANY RELATIVELY LONG-LIVED SPECIES, VARIATION IN POPULATION GROWTH RATE IS DRIVEN BY VARIATION IN REPRODUCTIVE SUCCESS AND RECRUITMENT. THUS, RESEARCHERS AND CONSERVATION PRACTITIONERS OFTEN FOCUS ON THE COMPONENTS OF REPRODUCTIVE SUCCESS AND THEIR ENVIRONMENTAL DRIVERS IN ORDER TO DETERMINE ACTIONS THAT MIGHT IMPROVE POOR REPRODUCTIVE SUCCESS TO GROW A POPULATION OR DECREASE REPRODUCTIVE SUCCESS TO REDUCE A POPULATION. IN THIS PROJECT, WE WILL ASSESS THE ENVIRONMENTAL DRIVERS OF THE COMPONENTS OF RECRUITMENT IN KING EIDERS, WHICH ARE A RELATIVELY UNDERSTUDIED HIGH PRIORITY SEA DUCK SPECIES. REPRODUCTIVE SUCCESS IS BELIEVED TO CONTRIBUTE MOST TO KING EIDER POPULATION PATTERNS, IN THE ABSENCE OF PERIODIC MASS STARVATION (FOURNIER AND HINES 1994). WE ARE AIDED BY DATA SETS ON KING EIDER CLUTCH SIZE AND NESTING SUCCESS COLLECTED AT KARRAK LAKE IN THE CENTRAL CANADIAN ARCTIC FROM 1995 TO 2019. WE WILL ASSESS THE EXTENT TO WHICH CLIMATIC INDICES SUCH AS THE NORTHERN PACIFIC INDEX AND NORTH ATLANTIC OSCILLATION INDEX HAVE EXPLAINED VARIATION IN KING EIDER CLUTCH SIZE AND NESTING SUCCESS OVER OUR STUDY PERIOD. WE ALSO WILL TEST THE EXTENT TO WHICH LOCAL TEMPERATURE AND PRECIPITATION, AS WELL AS GREEN-UP, EXPLAIN VARIATION IN REPRODUCTIVE METRICS. THUS, WE WILL TRADE OFF WHETHER CLIMATE DURING WINTER OR SPRING MIGRATION OR LOCAL WEATHER EFFECTS ON NESTING AREAS EXPLAIN MORE VARIATION IN KING EIDER REPRODUCTIVE METRICS. IN ADDITION, KARRAK LAKE COMPRISES ONE OF THE LARGEST LESSER SNOW GOOSE AND ROSSS GOOSE (I.E., LIGHT GOOSE) BREEDING COLONIES IN NORTH AMERICA, AND THE DEMOGRAPHY OF THESE BIRDS HAS BEEN WELL STUDIED. WE WILL TEST THE EXTENT TO WHICH THE POPULATION DYNAMICS OF LESSER SNOW GEESE AND ROSSS GEESE EXPLAIN VARIATION IN REPRODUCTIVE SUCCESS OF KING EIDERS DURING THE STUDY PERIOD. THIS IS PARTICULARLY INTERESTING BECAUSE THE LIGHT GOOSE COLONY RAPIDLY EXPANDED FROM 300,000 BIRDS IN THE EARLY 1990S TO 1.3 MILLION INDIVIDUALS IN 2009 BUT HAS COLLAPSED TO 230,000 BIRDS IN 2024. UNDERSTANDING THE ENVIRONMENTAL DRIVERS FOR KING EIDER REPRODUCTIVE SUCCESS WILL FILL AN IMPORTANT INFORMATION GAP ABOUT HOW THIS SPECIES AND SEA DUCKS GENERALLY MIGHT RESPOND TO CLIMATE CHANGE AND LOCAL WEATHER IN FUTURE YEARS. FURTHER, LINKING KING EIDER REPRODUCTIVE SUCCESS WITH LIGHT GOOSE POPULATION DYNAMICS WILL BE IMPORTANT IN UNDERSTANDING HOW SPECIES WITH DIFFERENT LIFE HISTORIES INTERACT IN AN ARCTIC ECOSYSTEM, WITH IMPLICATIONS FOR OTHER MULTISPECIES INTERACTIONS AMONG SEA DUCKS AND OTHER TAXA ACROSS THE NORTH.