Northern Flickers, which are common all across North America, occur in two subspecies, Yellow-shafted in the north and east, and Red-shafted in the west. In flight Red-shafted flickers show a salmon-red colour under the wings and tail, whereas the Yellow-shafted show a golden-yellow colour. That seems straightforward enough: red=Red-shafted, yellow=Yellow-shafted. But on perched birds the feather shaft colours don’t always show, so you have to rely on the differences in head markings: a red mustache on male Red-Shafted flickers, black on male Yellow-shafted. Females lack mustache marks. Both male and female Yellow-shafted have a red crescent on the nape, which Red-shafted birds lack. Yellow-shafted flickers have a grey crown and brown cheeks, and Red-shafted have a brown crown and grey cheeks. All this can be a little hard to keep straight in your head.
Male Yellow-shafted Northern Flicker
Male Red-shafted Northern Flicker
Now to complicate things. Although the two forms were once considered to be separate species, there is a large zone on the western edge of the great plains where their ranges overlap, and intergrades occur here, with a mixture of field marks from each subspecies. In fact, intergrades are often seen throughout the range of Northern Flickers. But here in Calgary, on the eastern slopes of the Rocky Mountains, we are smack dab in the middle of the overlapping ranges, and almost every flicker you see shows signs of its mixed heritage.
Intergrade male Northern Flicker
The bird in the above photo appears to be a male Red-shafted Flicker, with no nape mark and a red mustache, but the colour under the tail is distinctly yellow. On some intergrades it is a sort of pumpkin-orange, in between yellow and red. You can also see birds with Yellow-shafted head markings but red wing and tail linings.
In Calgary Northern Flickers are here year-round, and they readily come to feeders. You can learn to identify individuals by their mixed-up field marks. I always take note of the markings and their colours. The most interesting ones have in-between head markings. Here is a male bird with a red mustache but also a red nape mark.
Below is the same bird, showing salmon-red feather shafts.
I haven’t yet seen a male flicker with a black mustache and no red nape mark. I wonder if that combination is possible.
The bird below, busily excavating a nest box, shows only a faint hint of the red nape mark, but also a red mustache.
Odder yet are the birds with mustaches that are both red and black.
Flicker with mixed black and red mustache
The bird in the two photos above looks basically like a Yellow-shafted Flicker with a little red in what should be a black mustache, but note that it also has the brown crown and grey cheeks of a Red-shafted.
The bird in the two photos below has much more black in the mustache, and the crown and cheek colours are switched.
I have heard of, but never seen, flickers with a black mustache on one side of their face, and a red one on the other.
I think most birders don’t usually take note of these in-between birds. But here is a map of reports from eBird, with purple showing where intergrades have been reported.
It would be interesting to hear from birders across Canada as to how common intergrade Northern Flickers are in your area.