Hi, Robert -
I can add a few clarifications,and perhaps some fog. At least initially, the
decision to not include subspecies in the 6th edition of the AOU Checklist was
made because the Checklist committee had decided to extend the area covered to
include Mexico and Central America, and concluded it would take too long to
work out subspecies taxonomy of the newly included neotropical species, but
they expressed their intention of doing subspecies in the next edition.
Subsequently, there has been a lot of debate among bird taxonomists and other
taxonomists about the value of naming subspecies, and the AOU (now AOS and
NACC) have quietly backed away from inclusion of them in later editions.
Subspecies are still being named and revised, although at a much slower pace,
and much more frequently in the neotropics than north of Mexico.
The subspecies named prior to 1957 include slight variations in size and/or
plumage, up to incipient species and even cryptic species. With I think 2
exceptions (Gunnison Sage Grouse and Cassia Crossbill) all of the "new"
species recognized in North America since 1957 have involved promoting
previously named subspecies to species status.
The "subspecies groups" reflect a recognition that in many species, including
Horned Larks and Song Sparrows, more than one level of differences is present
among the named subspecies. Fox Sparrows provide a good example. Four
subspecies groups are recognized, and have been proposed for elevation to
species status - Sooty Fox Sparrow, Red Fox Sparrow, Thick-billed Fox Sparrow,
and Slate-colored Fox Sparrow. Each group has considerable geographic
variation within in, captured by the subspecies names, but the latter variation
is evolutionarily minor compared to the differences among the four groups.
The horseshoe and ring species concepts are somewhat controversial, and more
recent classifications of Herring Gulls and their relatives have pretty well
broken up that "ring."
Because subspecies as currently recognized are such a heterogeneous mix of
minor and more substantive variations, a lot of ornithologists are not very
interested in them, but they do provide a language for discussing geographic
variation. Imagine what the discussion of the odd, pale Song Sparrow on
Sauvies Island would have looked like if there were no names to use for
proposing potential origins for that bird.
Wayne
On 3/11/2019 10:12:40 PM, Robert O'Brien <baro@xxxxxxx> wrote:
Here is some history of subspecies in US ornithology, with example for Horned
Lark. (Song Sparrow would generate something similar)
There was a time in the development of ornithology in the United States when
subspecies were "all the rage". They were being described right and left in
minor scientific articles in ornithology journals, usually based on museum
specimens often collected by the people that were describing the subspecies.
This stopped in 1957, after which the American Ornithological Association (AOU,
now the AOS (society)) stopped including subspecies in their periodic
Checklist, listing all the current North American species. I would guess they
decided it was getting out of hand. Such subspecies are sometimes called
'races' or 'forms' to this day.
For instance last month I posted a listing and image of all the Horned Lark
subspecies painted by Rex Brasher in about 1930, as part of his epic Birds and
Trees of North America. Each subspecies has an AOU-assigned subspecies name and
number, 474 (the original one described I guess) and then 474a-m). 13
subspecies in total. This does seem excessive, species-splitters going wild..
Rex was largely sedentary in the latter (painting) period of his life and could
only have painted these 14 from museum specimens, likely at the Smithsonian in
New York.
My previous post is here
https://www.freelists.org/post/obol/Speaking-of-SubSpecies ;
[https://www.freelists.org/post/obol/Speaking-of-SubSpecies]
and his accompanying Horned Lark paintings at
https://www.freelists.org/archives/obol/12-2018/jpgTR8oZLPg9M.jpg ;
[https://www.freelists.org/archives/obol/12-2018/jpgTR8oZLPg9M.jpg]
Notably our threatened Streaked Horned Lark is illustrated in one of this
paintings, 474g right before the Scorched Horned Lark (ya gotta love that name).
It seems that the current 'keeper' of subspecies is Cornell University through
eBird, at least as far as the general public is concerned..
Looking at eBird there are a number of choices in addition to the fundamental
'Horned Lark' which covers as a species all subspecies or races. But, instead
of listing all the original 1930's subspecies, groupings are selectable, many
of which are found elsewhere in the world. Currently all 'Horned Larks'
worldwide are considered to belong to the same species, at least by
Cornell/AOS. I have attached to this post range maps for the locations where
these various 'forms' are reported in the US. .Note that eBird does not
individually accept records for our threatened Streaked Horned Lark subspecies
striata, but 'lumps it into a group.
Horseshoe subspecies have been discussed in the current thread on OBOL. Another
related phenomenon is circular species of which Herring gull is one. In this
case the horseshoe would lie on its side and go all the way around the world
horizontally. There is a gradual variation (cline) in appearance around the
ring, but when the ring almost closes near the start, the physical appearance
of the 2 adjacent gulls is quite different. Where to draw the line as to
species, much less subspecies? DNA analysis could certainly look at this
variation at the molecular level but it seems likely there would be a gradual
variation in DNA, as well as appearance, so any DNA definition might be
arbitrary as well.
See attached image for current eBird designation of 'subspecies' in the case of
Horned Lark. Corrections and/or clarifications to the above expose' are invited.
Bob OBrien Carver OR
