This is a follow-up to my post on IBLE of 25 January, 2008 which began to deal with the complexities of Horned Lark subspecies present and identifiable in Idaho during the winter months.
Photo: Bob Martinka, taken
in Helena Valley, MT
2/4/08. Probable E.a.
merrilli intergrade.
Let me say, right off the top, that the more I investigate this situation the more complex and not straight forward it becomes. Although there are 21 subspecies recognized by the American Ornithologists Checklist, 5th edition (1957), it must be understood that this species exhibits much intra-population variability, with numerous intermediate populations between the established races. What we have are endless variation possibilities, with micro-populations based on color and size differences resulting from a blending of the typical forms of each subspecies population. Clinal variations and differences are the rule rather than the exception, with “typical” being a nice technical term that has difficulty finding much viability in the realities of field observation with this species.
With that said, let’s look at what identifiable subspecies have been documented to be present in Idaho, where they can be expected to be found (based on recorded, available data), and how these subspecies can reliably be identified (perhaps) by observers in the field, especially outside of the breeding season.
(Let it be it noted here that there is a dearth of banding data available, which if it were systematically gathered by knowledgeable personnel at strategic and appropriate habitat locations throughout the state during the winter months, when conditions are unfortunately most unfavorable to human activity, many of the missing pieces of Horned Lark dispersal and distribution would become available. )
Subspecies that have been observed and/or collected in Idaho:
Eremophila alpestris arcticola
This race is the largest of the western subspecies and regularly migrates from its breeding grounds in Alaska, the Yukon and through the mountains of British Columbia south to Northern California and east to Wyoming. This is the only western race that does not intergrade with adjacent forms, therefore we do not see the potential variation here that is the bane of other subspecies field identification.
It has a white throat and eyebrow stripe, a pale, neutral gray back, boldly streaked with dusky brown, a pinkish-buff nape which bisects the streaking of the dorsum which continues onto the crown, a trait unique to this subspecies and not detailed in field guides. Its larger size is noticeable with careful comparative observation, especially appearing somewhat plumper than any of its potential winter associates.
It has been recorded by both collection (first record, Coeur d’Alene, 1897) and observation along the north/south length of the state. Specimens in the Colorado Museum of Natural History document 109 records from southern Idaho, spanning the area from Ada County to the eastern state border, from 4 November to 20 February.
The subspecies is possible anywhere in the state beginning at about the start of October until the beginning of March.
With that said, let’s look at what identifiable subspecies have been documented to be present in Idaho, where they can be expected to be found (based on recorded, available data), and how these subspecies can reliably be identified (perhaps) by observers in the field, especially outside of the breeding season.
(Let it be it noted here that there is a dearth of banding data available, which if it were systematically gathered by knowledgeable personnel at strategic and appropriate habitat locations throughout the state during the winter months, when conditions are unfortunately most unfavorable to human activity, many of the missing pieces of Horned Lark dispersal and distribution would become available. )
Subspecies that have been observed and/or collected in Idaho:
Eremophila alpestris arcticola
This race is the largest of the western subspecies and regularly migrates from its breeding grounds in Alaska, the Yukon and through the mountains of British Columbia south to Northern California and east to Wyoming. This is the only western race that does not intergrade with adjacent forms, therefore we do not see the potential variation here that is the bane of other subspecies field identification.
It has a white throat and eyebrow stripe, a pale, neutral gray back, boldly streaked with dusky brown, a pinkish-buff nape which bisects the streaking of the dorsum which continues onto the crown, a trait unique to this subspecies and not detailed in field guides. Its larger size is noticeable with careful comparative observation, especially appearing somewhat plumper than any of its potential winter associates.
It has been recorded by both collection (first record, Coeur d’Alene, 1897) and observation along the north/south length of the state. Specimens in the Colorado Museum of Natural History document 109 records from southern Idaho, spanning the area from Ada County to the eastern state border, from 4 November to 20 February.
The subspecies is possible anywhere in the state beginning at about the start of October until the beginning of March.
E.a.hoyti
Although not mentioned in Birds of Idaho (Burleigh, 1972), it undoubtedly occurs regularly during winter, most probably throughout the length of the state. One of only three races that are entirely migratory, it breeds from northern Baffin Island to northern Alberta, across Canada to Ontario, wintering south to Nevada (including Idaho) and across to Michigan (Beason, BNA, #195). Burleigh does cite records of E.a.enthymia from the southeastern portion of the state based on identifications by provided Oberholser of specimens in the Colorado Museum of Natural History. I question this based on Beason who contends that E.a.enthymia is a Great Pains breeding bird whose range extends a bit further south in winter, but is a long distance from Idaho (and inconsistent with the numerous records cited). Further fitting into the picture of misidentification is that enthymia is morphologically very similar to hoyti, and would be difficult to visually tell apart…and as mentioned, Burleigh does not even reference hoyti as a visitor to Idaho, which it is undoubtedly.
This race is primarily identified visually by its white eyebrow and yellow throat.
E.a.utahensis
This is one of three breeding races of this species in Idaho, this one primarily in the southern portion of the state, documented as far north as Custer County. Although most of the population moves out of Idaho during the winter months (this is the northern boundary of it breeding range), there are scattered remnants of the population that overstay the winter, often being most readily found in larger mixed flocks of the species.
Unique to this race (for Idaho) is its matching yellow eyebrow stripe and throat (although the stripe may be a bit lighter). Additionally it had a drab nape and crown, and dusky brownish back.
E.a.alpina
Breeds in the coast mountain ranges of western Washington, and primarily winters in the lowlands surrounding those mountains. Apparently it does occur regularly in northern Idaho, most often reported in association with flocks of E.a.arcticola. Specimens have been taken primarily in February, although there is one September record from Lewiston, and one southern Idaho record on November 23 from Emmett.
According to Beason it resembles the migratory arcticola but “E.a. alpina is smaller and less brownish than E. a. arcticola with a darker back and more pinkish nape, uppertail-coverts, and upperwing-coverts. (This may be a difficult one to separate in the field.)
E.a.lamprochroma
Another Idaho breeder, this one in the southwestern corner of the state, according to specimens not north of Ada County nor east of Owyhee County…a very restricted breeding range in the state. It apparently can (and does) occur in the winter months also, while occasionally also being present in northern Idaho during that period, apparently moving from its breeding grounds on the arid sagebrush plains of eastern Washington.
Similar to E.a. arcticola in appearance (along with E.a. alpina), the base color of the back is darker (less gray) than arcticola, with the striping and base color blending together, lacking the dramatic contrast of arcticola. Also, to my knowledge, the dorsum striping pattern is not seen on the crown.
E.a.merrilli
This is the third breeding population in Idaho, most common in the north, and found from the Canadian border to as far south as Washington County. In most areas it is absent during winter, retreating to the southern portion of its range (n. California), although there are two Moscow, Latah County specimen records from December. Apparently it is resident in the Lewiston area all year long, at times very plentiful and easy to find in “flocks of 20-200” (Burleigh, 1972).
This is the darkest of all the subspecies, with the back being blackish brown, nape brownish, extending around the wing wrist, the throat yellow, and a lighter yellow eyebrow line. It is fairly easy to pick out of any mixed group because of it contrasting dark color.
To date five subspecies of Horned Lark have been documented in Idaho. Few, if any, birders or researchers out in the field have paid much attention to plotting subspecies presence, therefore there is still much to learn of the movements of these groups, especially during migration and winter. For the amateur who likes identification challenges…and for the professional wanting to add some important pieces to the body of knowledge of this species, opportunities abound.
Some photos of Horned Lark subspecies in Ada County:
(Be advised that this is far from a completed work.... Much field work remains to be done. Photos of Horned Larks are always welcome.)
Harry Krueger
Boise, ID
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