Hello,
To continue this thread, I became more interested in the song
differences of Warbling Vireos after hearing the presentation at the CFO
convention. Having moved to Colorado from Acton, Ma just a year and a
half ago, I was very interested in the differences people reported. I
could identify the western bird by the sound quality - the beginning of
the song sounds so similar. The eastern
Warbling Vireos were a very common enthusiastic singing bird I heard all
the time in spring/summer when kayaking on the Assabet, Sudbury,
Concord, and Nashua rivers. The song was much longer than the western
counterpart and as far as I remember always ended with the quite
emphatic upward inflection. The western birds here seem to have a much
shorter song - one that is truncated. I guess the wisdom says it ends
less emphatically and not on an upward tending frequency. However, just
this past Friday hiking in Gregory Canyon in Boulder, I heard what I
thought was the same bird sing a relatively short song, sometimes ending
with downward inflection and other times ending upward, but always of
shorter length than the eastern birds I remember.
How much of song is genetically stamped, and how much is learned is
something I don't know much about, so I will leave that to the
professional biologists/ornithologists.
Jeremy Winick
Westminster, CO
Adams County
“What is wanted is not the will to believe,
but the wish to find out, which is its exact opposite”
... Bertrand Russell
On 06/09/2012 08:20 PM, Bob's Email wrote:
Hi
Recently there has been exciting chatter that Colorado could be the home for both the
"eastern" and "western" populations of the Warbling Vireo. Further speculation
implies these two populations may reflect two different Warbling Vireo species! Within the eastern
and western populations there are intermediate populations, thereby causing extreme difficultly in
physical identification for each group. It has been suggested that the best way to separate the
two groups is by song, the western group apparently ending its song on an upward inflection and the
eastern on a downward inflection. Downward-inflected songs have been noted on the eastern plains,
leading to the assumption that the eastern group may be present in that region. On a recent family
trip encircling the West Elk Mountains in Gunnison, Montrose, and Delta counties, I decided to don
my citizen scientist sun hat and see what the Warbling Vireo sounded like in that region of the
state.
A usual pattern of their song began to emerge. Frequently the song would
consist of two sequences, the first sequence ending on an upward inflection and
the second sequence ending on a downward inflection or a neutrally-inflected
note. In addition, the song would often consist of one sequence ending with an
upward inflection, and infrequently the song would include just one sequence
that ended on a downward inflection. Sometimes the song of either sequence
would be sung repeatedly of just one sequence or the other.
So what can be learned from this brief experiment in citizen science that
produced a mixed message about the sound of the western population of Warbling
Vireo? Does the variation in the sequence of the Warbling Vireo song represent
a normal pattern of variation within the species and with each of the Vireo's
two populations?
Does the variation in the song pattern reflect a phase of the Vireo's phenology
as it does with some other species where the song pattern and length changes
depending on if the bird is in territorial, breeding, or after breeding mode?
Could time of day indicate what song variation is being sung?
There seems to be a lot more that is unknown than known, and we in Colorado
could contribute be being alert to what song is being sung when and where.
Bob Righter
Denver, CO
Sent from my iPad
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