Discussion
The habitat features that the "Western Flycatcher" prefers are distinctive among Alberta birds. A shady spot, with a slope or cliff near water was common to all sites. The bird chose a deciduous riparian oasis in the middle of homogenous, mature conifers. The slope coupled with the stream made the immediate riparian area more open than the surrounding conifers. The swatch of riparian, deciduous habitat provides an open area for foraging and display. The open space inherent in this area would reduce signal degradation of song compared to the conifer forest surrounding it. The cliff provides potential sheltered nesting areas. We did note, however that the "Western Flycatchers" were using the surrounding conifers as well as the deciduous, riparian area. When we began playback on many sites, we found that the birds would approach through the conifers, often upslope. The coniferous forest is part of the bird’s territory and may provide nesting materials, shelter, foraging opportunities or access to sunlight and heat.
The noise level of the stream also presented some problems for detection. The birds were often slow to respond to playback. At many sites, it took as long as 10 minutes to hear or detect a bird responding to playback. There are two possibilities: either the bird responds as quickly as possible, (but it sometimes takes the bird a while to hear the playback while moving about in its territory) or the bird attempts to sight the intruder initially and does not respond vocally until later. At many sites, the water was quite loud. Hence, it was very much by chance that we would hear the bird singing. The bird had to be very close to us in order to be heard. Although it could be argued that the playback may not have had the volume to be discerned above the water, the quality of the song transmission and how well the birds receive it through the water noise are not known. The reduction of signal degradation in this space may outweigh the background noise the habitat offers.
Studies of territoriality in flycatchers using playback have used a mounted decoy atop the speaker (Stein 1963). The visual element to the flycatcher response is important. This can be implied from their predilection for singing from exposed perches and use of obvious display (Skutch 1997). Perhaps the "Western Flycatcher" will not commit the energy to responding aggressively until it is sure of what it is dealing with. One bird we encountered was spotted silently approaching the source of the playback. It continued to move closer, perching about 10 m away, looking around vigorously. As it looked away from us, we would play the tape. It would turn around and silently, come closer, searching even more frantically. This continued for about 4 minutes when the bird finally broke into vigorous song about 2 m from the source of the playback. Without the visual confirmation of an intruder, the bird seemed hesitant to vocalize.
The first record for a "Western Flycatcher" in Alberta occurred in 1954 (Salt and Salt 1976) near Turner Valley, not coincidentally, an area where there is a high concentration of them today. Campbell et al. (1997) notes that the Western Flycatcher complex has expanded its range north and eastward in British Columbia since the mid-1940s. It is now common in areas of British Columbia where it was once a rarity. This expansion would coincide with the first sighting in Alberta and may explain the increased number of sightings for the province. If the "Western Flycatcher" has been expanding its range, has it reached the limit of eastern expansion? Elevation does not seem to be an issue. We have noted that they prefer the middle elevations in the mountains. They are, in fact more common in the foothills at the lower elevations. Habitat would seem to be an essential issue limiting the birds’ expansion east. The sites in the interior of the mountains were often in steep-walled canyons while the foothills sites were often more open. Many sources (Bent 1942, Davis et al. 1963, Campbell et al. 1997) note Western Flycatchers using human structures such as bridges, barns, and house eaves for nesting sites. This is a plausible means for the "Western Flycatcher" to expand eastward although there are no confirmed records along the rivers east of the foothills.
Status in Alberta
Our study has revealed that simply classifying members of the Western Flycatcher complex within our province as Cordilleran Flycatchers is not wholly accurate. Based on our preliminary findings and the unpublished work by Richard Cannings and Eugene Hunn, it is likely that the Pacific-slope Flycatcher occurs in Alberta and may possibly be the only "Western Flycatcher" in Alberta. With this in mind it is difficult to suggest a status for a bird whose true identity we do not know. Additional work will be needed to determine the identity of the Alberta populations of Western Flycatchers before management implications are known.