Male/Female American Robins

American Robins exhibit subtle sexual dimorphism. Though there are some other subspecies that can complicate the issue, here in NJ the males have darker brown and brighter orange than the females. Another complication is that immature males also resemble the females; it's safer to identify a mature male while distinguishing immature males and mature females is going to be more problematic.

This looks to me to be a good example of a mature male. The head's pretty dark while the breast/belly are a fairly bright orange.
April 18, 2023 at Duke Farms
Photo 272140697, (c) jpviolette, some rights reserved (CC BY-NC)

The robin below has lighter head coloring and paler orange. This picture was taken in March, and they ought to have adult plumage after a year, so I suppose it's possible this is a male born in 2022 that hasn't quite gotten its adult plumage. If the bird is over a year old though, we could safely claim her as a female robin.
March 20, 2023 at the Raritan Water Power Canal
Photo 268021743, (c) jpviolette, some rights reserved (CC BY-NC)

Of course, before robins get their immature plumage, they have the more distinctive juvenile plumage. My only picture of that shows a sitting bird, so you can only partially see the speckled plumage they have when they 1st fledge. (My suspicion is that the speckled plumage is better camouflage than the adult plumage, making them less conspicuous while they're still learning how to survive.)

June 7, 2012 at Mt Pleasant Villas
Photo 11330831, (c) jpviolette, some rights reserved (CC BY-NC)




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