Mysterious Orange Scarlet Tanagers

As the name suggests, Scarlet Tanagers (the males that is) normally sport scarlet red plumage, apart from their black wings and tail. I captured this image of a classic red Scarlet Tanager at the James H. Fullard Nature Reserve in Eastern Ontario in summer 2020.

However, in 2021, I observed two different individuals (150 km apart) who were decidedly orange and straying towards yellow.

I photographed the gorgeous yellow-orange individual on Canoe Lake Road in May 2021 on yet another wonderful birding adventure with Jon Ruddy of Eastern Ontario Birding.

I captured a different orange bird in the west end of Ottawa a month later (also on a tour with Jon Ruddy).

Here is the same Ottawa bird flying away. This shot shows that this individual has a yellow belly and undertail, but orange hood, throat and rump.

Earlier this week, I read a blog post by bird photographer Ron Dudley in which he discusses photos of orange variant house finches. He explains that in birds with yellow-orange-red colouration, the actual pigment expressed is due to their diet.

A brief Google search led me to this scholarly article in the Journal of Evolutionary Biology which demonstrates that this is the case for all bird families with yellow to red plumage! The abstract states: “when we look at plumage coloration separately from bare part coloration, we find there is a robust and significant association between diet and plumage coloration”. The article also suggests that yellow colouration is less costly to achieve, but red colouration is more attractive to females.

I will note that female scarlet tanagers are in fact yellow in colour, and males shift to yellow out of breeding season. Here is a female or non-breeding male I photographed in September 2018 in Ottawa.

This does lead one to wonder what food the two orange variant scarlet tanagers ate that their more common red counterparts didn’t – or visa versa, and whether the two orange birds were successful breeders. I may never know.