Several months ago we were asked the question, what makes a Junco a Junco? Our answer at the time was short, incomplete and not very useful. I did think, though, the question would make for a good column, or why are orioles and meadowlarks lumped in the same family as grackles and blackbirds? Although the member asking the question did not need a starting-from-square-one-answer, let's do just that because the classification of birds is interesting, and an on-going process.
Indigenous peoples have been giving names to birds from a time before time. However, lets start with Aristotle who brilliantly grouped birds into three categories: Those living on land, those living on water, and those living at the edge of water! Two millennium later, Belon separates birds into six groups: raptors, web-footed waterfowl, marsh birds without webbed feet, terrestrial birds, large and small arboreal birds. Two hundred years later Willughby and Ray classify birds morphologically (shape and looks).
Linnaeus in the mid 1700's devises binomial nomenclature. Later, based on Darwin, researchers begin to classify on the basis of common ancestry. Just over a hundred years ago, Furbinger and Gadow devise modem classifications based on numerous anatomical characteristics. For the first time all passerine songbirds are grouped together. By 1960 Wetmore, using newly developed information, adjusts the classifications to what we see today in most North American field guides. In the 1980's Charles Sibley and Jon Ahlquist proposed a major rearrangement of the orders and families based on DNA comparisons.
Starting with the binomial nomenclature of Linnaeus, birds belong to the Kingdom Animalia, Phylum Chordala (vertebrates), Class Aves (birds). In descending placement, Order (31 orders of living birds - Passeriformes, perching birds, for example), Family, Genus, and finally Species. Related species are placed in a genus, related genus are in a family and related families in an order. So we have come right back to the original question, why a junco? Given it is a bird, because it has feathers, where do we go from here?
We have arrived at the Order Passeriformes. Birds in this order are recognized by their overall perching physique (three toes forward, with a well developed hullus - back claw) and by the complex structure of their syrinx (voice box). Family Emberizidae is made up of birds that are generally ground dwelling, are rather drab in color, have short conical bills, feed on seeds in winter and primarily insects in summer. That is, sparrow-like birds such as towhees, sparrows and juncos. We're getting closer.
(Click photo to
view larger image.)
Genus Junco. A Latin word for rush or rushes. An inappropriate name since they are seldom seen, if at all, in wetland reeds. Species hyemalis (winter) for this is when they are commonly seen. Their common species name is Dark-eyed Junco, for they all have dark eyes. There are six recognizable populations (sub-species or races): Oregon, Pink-sided, Gray-headed, White-winged, Slate and Red-backed. In the very southeastern comer of Arizona there is a separate species, Yellow-eyed Junco - Junco phaeonotus (species name from Greek word notos meaning back referring to the plumage color of its back, rather than anything having to do with its yellow eye).
Note that the birds genus is always capitalized, while the species is not capitalized. Therefore Junco hyemalis. When in print the scientific names are always in italics as is family and order. When hand written the scientific names should be underlined. If one wishes to denote the sub-species, a Oregon Dark-eyed Junco would be Junco hyerrialis oreganus.
We have jumped over Sibley and Ahlquist and DNA. These folks have proposed an entirely new and somewhat radical phylogeny of birds based on chemical rather than physical methods. Already New World vultures have been shifted to the stork order from the hawk order. Also, many Australian passerines were found not to be related to warblers and thrushes whom they resemble. Rather they are related to each other in a diverse array of forms. Some interesting realignments may take place in the future.
Wait, we are not through! Due to their remarkable similarities in structure, looks, habitat and behavior they are placed in their own genus, no matter how badly named Species? Species is the basic unit of classification of living organisms. In other words, to quote from the manual: "By the prevailing Biological Species Concept (BSC), a species is a group of potentially interbreeding individuals that share distinctive characteristics and are unlikely to breed with individuals of another species."
Therefore there should be no gene flow (genetic material) between species. Where their ranges overlap, Dark-eyed Junco races frequently interbreed producing offspring with intermediate coloration. The fact that Dark-eyed Junco races are in general separated geographically but not reproductively, is evidence that the different forms, once each considered separate species, are actually races of a single species. There you have it – Dark-eyed Juncos!
Good birding, gone birding.
© Photo by Beryl Stark
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