Regardless of whether or not Myrtle and Audubon Warblers are a single
species or not, I continue to treat them as distinct. Even if the
professionals consider them a single species (this could always change as it
has with Towhees and Orioles) I still find it worthwhile to distingish them.
In so doing, I have made some interesting discoveries that would not
otherwise be possible. What I mean is, if I lumped them together, all of my
bird notes would read: Yellow-rumped without the distinction to subspecies.

Today I was able to further my observational knowledge of them. I imagine
most people are aware that these two do not give the same call-notes. Since
I identify them to subspecies by feather detail, I wondered if I would be
capable of an auditory identification. Sure enough, the Audubon's Warbler
gives a slightly higher pitched, rising call note that is also softer than
the relatively harsh, dry, lower pitched 'check'. I stood under the
cottonwoods where there was a small flock of Yellow-rumped Warblers feeding
in the canopy. I was able to identify them all by sound and would confirm
my identification with the binoculars.

Since I keep track of the two subspecies in my notes, I have also discovered
that only the 'myrtle' race appears to overwinter (I suspect it travels
farther north and East(within the province) than the 'audubon' as well) and
that the two do not appear in a 50-50 ratio. The Audubon's appeared first
this spring (March 10) and outnumbered the Myrtle until mid-April. Then the
myrtle race largely outnumbered the audubons. Recently, they appear to be
50-50. This may be locally significant or a mere artifact but nevertheless,
I do believe it is worth keeping track.

I imagine the songs of the two "subspecies" differ as well. Another
interesting experiment to perform in the field.

For those who do not distinguish to the sub-specific level, I encourage you
to do so, especially when the two subspecies are readily identifiable as in
this case. The added amount of knowledge is entertaining and one never
knows, the taxonomic "splitters" may challenge the "lumpers" once again.
But despite the taxonomic classification from the experts, field observers
should consider what interests them as well.
Cheers,

Don Cecile
Port Alberni, BC, CANADA V9Y 6Z5
eMAIL: dcecile at cln.etc.bc.ca