On: Tue, 1 Mar 1994 Eugene Hunn <hunn at u.washington.edu> wrote:
>
> Al,
>
> I agree on the towhees but feel the crow situation may have more in
> common with song sparrows, juncos, flickers, etc. I have long urged
> someone at the University to find a student wishing to do a thesis on the
> questions. The obvious starting point would be a systematic analysis of
> vocalizations.
>
> Gene Hunn.
>

I am really surprised that the NW Crow question has not been tackled
by any one of the DNA gurus, or has it and I don't know about it. The
question of how much geographical variation is "too much" for a single
species, such as the three that you mention has always bothered me. A
big problem is that the data are confounded by all sorts of variables, one
of which is the misuse of the subspecies concept. Birds like the Song
Sparrow, Savannah Sparrow, Red-winged Blackbird and lots of others have
been over split into way too many subspecies. Much of the variation in
these forms is clinal, not dissected into smaller, identifiable populations.
At the same time I feel as if some good species may have been overlumped
within these highly variable species. My version of a good species is kind
of a mix between the biological and phylogenetic, not very satisfying, and
only a personal opinion. Hybridization does not bother me, especially when
it is rare. Hybrid zones, where most or all of the individual birds are
hybrids, also does not bother me, as long as the zone is relatively stable
and narrow. Deciding on what narrow actually means is subjective. If we
consider Kumlien's Gull to be a hybrid zone between the L.g.glaucoides and
Thayer's Gull, then the zone is too wide, but it may not be in Western/
Glaucous-wing. My opinion would be to keep Glaucous-wing and Western as
separate species but lump the Iceland complex. Similarly, I would split the
Orioles, Towhees, etc. Some other groups are much more complex, for example,
the Juncos. By applying my loose hybrid zone criterion, I would split off
White-winged, and Grey-headed, keep Oregon and Slate-colored together (assuming
that J.h.cismontanus is actually a hybrid swarm), and I don't know about
Pink-sided since I have little knowledge about its range and interaction with
the other forms but I have a feeling that it would be split off. BTW, in my
undergraduate years I did a phenetic analysis of Juncos, based on skeletal
measurements. I was extremely surprised at the fact that while White-winged
Junco is similar to Slate-colored in plumage, it is incredibly different in
skeletal morphometrics: they are huge, short-winged and long-legged if I
remember correctly. There is a general size cline in Oregon/Slate-colored,
but Pink-sided is bigger than either of them. As well, White-winged Junco X
Pink-sided Junco hybrids are very rare, I recall that less than five are known.

Bird populations that are isolated from each other, and show differences in
two data sets (i.e. plumage, song characteristics, behavioural characteristics,
genetic data) I would split off. If they only differ in one type of characteristic I would hold off. So I would split Belding's Sparrow from Savannah, Northern
from southern Sharp-tailed Sparrow, split the Fox Sparrow. As you can see,
it would be a mess if they allowed me in the AOU checklist committee, don't
worry it will not happen. I enjoy the topic of species concepts, and I am
merely thinking out loud hoping to incite some discussion. In general, I
think that species concepts are really a tool. You choose the one that will
answer the question that you are interested in. Perhaps birders should take
hold of this idea and create a "Birding species concept", if you can ID it
then you can count it! How does that sound?

Al Jaramillo
jaramill at sfu.ca
Vancouver, B.C.