Leucistic American Robin

The highlight of Thursday’s trip to Heinz NWR at Tinicum was a leucistic American Robin. Except for a tiny stripe of gray on the wing, a couple of tail feathers, and the black eye, the bird (from my vantage point) was completely white - bright white. In all other respects - shape, posture, behavior, and flight - it was typically “robin.”

leucistic American Robin

If “leucism” is a new term for you, here are a few extracts from the Cornell Lab of Ornithology website on “Plumage variations: Albinism or Leucism?”:

“Albinism is a genetic mutation that prevents the production of melanin in the body. Leucism is a genetic mutation that prevents melanin from being deposited normally on feathers .... leucism comes in two main varieties — paleness, an equal reduction of melanin in all feathers; and pied, an absence of melanin in some feathers creating white patches .... It is also possible for a bird to be completely white and still have melanin in the body. In this case the bird would be considered leucistic and would have dark eyes because the mutation only applies to depositing melanin in the feathers. Albinistic birds have pink eyes because without melanin in the body, the only color in the eyes comes from the blood vessels behind the eyes .... Typically birds with abnormally white feathers do not survive long because they are so much more visible to predators. Those that do survive may have trouble attracting a mate. Consequently, the mutated genes that cause albinism and leucism are less likely to be passed on to a new generation.”

Link to article: “Plumage variations: Albinism or Leucism?”

leucistic American Robin

Other highlights of the morning were Blackpoll Warbler, Rusty Blackbird, and Golden-crowned Kinglet ...

Blackpoll Warbler

Rusty Blackbird

Golden-crowned Kinglet

There was also a nice variety of waterfowl and abundant numbers of White-throated Sparrows. Yellow-rumped Warblers seem to have moved on.

White-throated Sparrow - brown striped morph

Good Birding!!