Follow migration patterns.,
Pay attention to mating behavior.,
Observe nesting behavior.,
Examine the robin’s breast.
Female robins will move to an adjacent nesting territory during the summer. Male robins, by contrast, remain on the same territory year-round., Male robins bring females food — seeds, worms, or berries — in order to strengthen the mating bond. The female will warble noisily and flap her wings to communicate that she desires the male’s gift.
, After the female has laid eggs, she will remain in the nest for up to two weeks. During this time, the male will bring food to her and her young.
If you see two robins in a nest with hatchlings and one flies away to obtain food, the one left in the nest is likely the female., It is very difficult to distinguish between male and female robins using plumage.However, there are some subtle differences in the breasts of older robins.
In male robins in their second year of life, the gray fringe around the red breast, continues to widen. The breast itself tends to be larger than that of females.While the fringe around the breast of the female robins does not widen significantly as they age, the female’s red breast itself does continue to grow with age.
Knowing the robin’s age is important when utilizing breast characteristics to determine the sex of European robins.