Hi all, I wasn't able to make it out to see or record the possible Pacific-slope Flycatcher today, but I may try tomorrow with my recording equipment if I can find the time. Meanwhile, here are some pertinent pieces of information about separating the two species by ear.
First, the geographic variation in "Western" Flycatcher vocalizations is very complicated. I have Johnson's (1980) monograph in hand, which was the primary research responsible for splitting Western Flycatcher into Cordilleran and Pacific-slope. It's pretty thorough, but the vocal evidence for the split isn't necessarily clear-cut, and work in progress by Andrew Rush and Arch McCallum reinforces the idea that the vocal variation may be more clinal than many have previously believed. Depending on how the research pans out, the two "species" may be good candidates for re-lumping. Second, "Western" Flycatchers have a number of different vocalizations, two of which (the dawn song and the male position note) are known to differ between Pacific-slope and Cordilleran Flycatchers, at least in "classic" cases. The dawn song is rarely heard after the sun rises. It consists of three very short (1-2 syllabled) notes that are usually repeated in an ABC pattern, about a second apart -- thus, it somewhat resembles the typical songs of Dusky or Hammond's Flycatcher, but it is much higher-pitched. The male position note is the usual call given by males during the day, and that's the one that people have been discussing on COBirds -- a single upslurred "wheeit" in Pacific-slope and a two-parted "WEE-seet" in Cordilleran. There is quite a bit of variation in these call notes in any one area, and even within individual flycatchers. I have recorded some Cordilleran Flycatchers near Estes Park that sounded very like Pacific-slopes to the ear. Birds that seem to make "both" calls are not necessarily hybrids. These are things to keep in mind when chasing the possible Pacific-slope. Also, sound recordings would be essential to making any case to the CBRC for a Pacific-slope in Colorado. Even if all you have is a cell phone or the "video" setting on your camera, fire that baby up if you find the bird. You might just get the documentation we need! Nathan Pieplow Boulder -- You received this message because you are subscribed to the Google Groups "Colorado Birds" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/cobirds?hl=en.
