Savannah Sparrow (Passerculus sandwichensis) Science Article 8
abstract
Savannah Sparrows (Passerculus sandwichensis) breeding on Kent Island, New Brunswick, Canada, are polygynous and sexually dimorphic in size. The sex of 7-d-old nestlingscannot be reliably identified by size alone, but juveniles begin to display clear sexualdimorphism in size by the time they reach independence, several weeks after leaving thenest.
N. T. WHEELWRIGHT et al, Field Ornithol., 65(4):520-529