Polygyny in Canada Geese: An Unusual Example of Nest Sharing

Abstract

We observed an apparent incident of polygynous behavior in Giant Canada Geese (Branta canadensis maxima). Two females were paired with the same male and concurrently incubated side by side within the same nest tub. Reciprocal changes in the number of eggs within each bowl during incubation indicated that eggs were shifted between nest bowls in both years. This behavior was observed at the same location in two successive years. Goslings hatched from both nests each year. Polygynous behavior in typically monogamous Canada Geese has rarely been observed, and nest sharing has not been previously documented.