Updated: 3 days ago
For birders who travel across Canada or down into the US, you will have noticed that some of the species we see here regularly in London can be found way out west, or even southwest into desert country. I had the opportunity to live in Alberta and the BC interior before moving to Ontario, so it has been interesting to compare the geographic variation in these widespread birds, especially conspicuous yard visitors that frequent my feeders. Although they may be grouped under one species, birds can look quite different in a western vs eastern yard.
An obvious example is the Northern Flicker woodpecker. Our London flicker is the Yellow-shafted form and the name becomes apparent when looking at a bird in flight. Underwing and under tail feathers shine a golden yellow. Males have a black facial “moustache” and bright red line across the back of the gray head. An eastern flicker was an unusual occurrence however, in my BC yard. There, the common form, or sub-species, was the Red-shafted. The red marking is absent from the back of the bird’s head. Instead, the moustache itself is bright red. Yellow-shafted and Red-shafted Flickers were once considered separate species but research challenged that classification and they were lumped under the common name Northern Flicker back in 1973.
This is thanks to the AOU or American Ornithologists’ Union - the authority body of all bird names lumped and split-- aka taxonomy. Across the country there are “intergrades” or hybrid flickers, where you might see a genetic combination of features from both red-and yellow-shafted parentage. Hybridization is one of the reasons the two forms aren’t considered separate species. In the arid southwest, one of the original Northern Flicker subspecies gained full species status and is called the Gilded Flicker. If you take a trip to Arizona, you might see this close relative.
Anyone who has a yard feeder has likely seen a Dark-eyed Junco eating seed on the ground. On the list of most common feeder birds, it’s near the top. My Sibley’s Field Guide states that there are six recognizable populations under this species name and shows range maps for each of the different looks. Our London junco, the Slate-coloured, ranges widely across North America. Males are a lovely slate gray with a pink bill and white belly. Pretty simple plumage! In the BC interior, this eastern subspecies would have been cause for excitement because of its uncommon status there. There is a map gap, perhaps due to the Rockies. The default junco in my western yard was the Oregon subspecies. Males show a strikingly dark charcoal hood with buffy/pinkish sides and back. Females have a similar hooded appearance, but not as contrasting. In London, the Oregon form, in turn, would be considered a rarity. Looks different, but is still part of the same general species. Some female Slate-coloured Juncos here have warm, brownish tones which might need a second, or third look (speaking for myself) before jumping to the conclusion that an Oregon Junco has found its way east. One really needs to see that noticeable demarcation between the body and head to claim it’s a hooded Oregon.
The London yard bird that originally got me thinking about this title topic is the chonky Fox Sparrow. Usually in mid-autumn, several birds arrive and stay for seeds for a few weeks. Even without binoculars, I can recognize them by larger size and their jump-kick feeding amongst fallen leaves. It was quite thrilling to see my first “Red” Fox Sparrow on a visit from the west. The bright foxy russet colouring on the body and breast streaks outdid the drab western birds I had been used to seeing. Actually, any sighting of Fox Sparrow in the BC interior was a good find, but along the Pacific Coast, in locations such as Vancouver, it wasn’t too hard to find a “Sooty” Fox Sparrow. Sibley’s guide describes four populations of this general species and the Sooty is darker and duller looking than our eastern subspecies. By looks alone, it seems surprising that they aren’t separate species.
There is a “Sooty” west coast version of another local sparrow too, our ubiquitous Song Sparrow. The sooty reference comes from its darker plumage. It’s the result of an increase in melanin pigment which enhances durability, making feathers tougher and helps prevent degradation. Extra melanin is a good defense against feather mites which may thrive in damp coastal environments. I have seen this subspecies in Haida Gwaii (formerly Queen Charlotte Islands), a far western coastal archipelago of Canada.
The Song Sparrow name goes hand-in-hand with the word variability. There have been up to 52 subspecies described for this brown, streaky sparrow, but that number currently stands at only 25 according to Wikipedia. What a downgrade ; ) Even within our London population, you may notice some slight differences in colour and streaking between individual birds. Something to look for!
Although several other species across Canada have had fairly recent name changes through lumping or splitting (i.e. Yellow-rumped Warbler was lumped and Northern Oriole was split to Baltimore and Bullock’s) I’ll just highlight one other widespread species in the tale of two yards, for the sake of brevity. If you look at a range map of the common Red-tailed Hawk, North America is completely coloured in from coast to coast...except for the arctic. A widespread presence however, doesn’t reveal the polymorphism of this Buteo. It runs a continuum from the very pale Krider’s form of the plains Red-tailed Hawk to adult birds with completely dark chocolate bodies and wings...yet still showing that orange-red-tail. Presence of a belly band and dark underwing patagial marks on the leading edge are two consistent field marks...plus that “red” tail on adults.
While living in BC, I saw amazing variability, even close to home, including birds with impressive dark rufous bodies. Then there was the Harlan’s Red-tail which gets special consideration but is still part of the general species. It has been bounced around by nomenclature committees, switching from being a complete species to being just a colour morph of the Red-tail. Now recognized as a sub-species, it can be easily identified by several field marks. Rather than the warm brown we see on our local Red-tailed Hawks, its body colouring is more of a neutral blackish hue. It has white streaks on the upper breast and the tail is usually whitish, edged in gray. Its like the colour has been zapped out of the plumage. Although, it looks so different, there is still interbreeding with other red-tails, so it's part of the same group... for now.
The concept of what defines a bird species has varied over time. Surprisingly, the criteria always seem to be in flux. This explains in part why there has been so much lumping and splitting in bird taxonomy over the past few decades. It’s not that new species have been created in the blink of an eye but that scientists may have gained new and improved information on genetic similarities. More in-depth (molecular) studies may have been carried out to help clarify where to draw the line. Arguments and discussions also continue to go back and forth about theories on speciation itself. Some argue the concept of species as a result of reproductive isolation. This is why birds living on remote islands are given extra study. Others prefer to base the definition on narrow groupings of birds with common genes. It’s been suggested that some researchers may promote splitting a species to garner more funding and protection for an endangered subspecies.
According to bird expert Peter Pyle, bird taxonomy is an imperfect but useful tool to try and communicate our knowledge of biodiversity. He says “The entire purpose of the species concept, to allow us humans to box and categorize taxonomic units in a standardized manner, becomes greatly compromised by a moving interpretation of what a species is.” It might be easier to celebrate biodiversity without the complication of a taxonomic structure, but we still need those names. It’s a human construct.
Birders who keep lists may either be dismayed and puzzled at losing a species on their tally thanks to an AOU lumping decision, or delighted when the verdict is a reversal, resulting in a net gain. I am still waiting for a decision from eBird reviewers in Arizona to find out if a meadowlark I saw twelve years ago in wine country is now considered the new Chihuahuan Meadowlark. At the time I saw it, the bird was known as the “Lilian’s” subspecies of our Eastern Meadowlark. Luckily, I still had photos in my files and hopefully they can be diagnostic. Hard core birders can really be persistent. Taking note of subspecies and variation, especially with photo documentation has value, especially for a large database like eBird. These records provide data which helps monitor trends in distribution of subspecies and possible range expansion or reduction.
To quote Shakespeare; “What’s in a name?
That, which we call a rose by any other name would smell as sweet. Or in this case, birds.
Photos from top:
Red-shafted Flicker, Yellow-shafted Flicker
Dark-eyed Junco (slate-coloured), male "Oregon" Junco, female "Oregon" Junco
"Red" Fox Sparrow, "Sooty" Fox Sparrow
Song Sparrow, "Sooty" form and not sure what this dark one is
Red-tailed Hawk, Harlan's Hawk (2)