Results

Figure 3. Distribution of the "Western Flycatcher in Alberta. Click here for a detailed view of sites found

In the 1999 field season, we located 41 sites where "Western Flycatchers" had established territories (Fig. 3). In Alberta, the Western Flycatcher breeds within the Rocky Mountains and the Foothills ecoregions. From our findings, its range in Alberta extends from Waterton Lakes National Park to Jasper National Park. It continues eastward beyond Cadomin in the north and Turner Valley in the south. It is most common north of the Highwood Pass and south of Nordegg. Of these sites, 37% were found within parks and protected areas. We performed the categorical habitat assessment on 36 of the 41 sites and the quantitative assessment on 30 of the 41.

 

The elevations of the sites ranged from 1153-1800 m. The mean elevation was 1533 m. Forty of the 41 sites had water as a component of the habitat. Except for one of these, the water body was a river or a stream (Fig. 4). The streams were often small but fast moving (Table 2). The riparian area averaged 22.8 m wide.

 

TABLE 2. Mean width of stream and riparian area.

Figure 4."Western Flycatcher" site along Bluerock trail near Sheep River.

 

Virtually all of the sites were surrounded by forest. Beyond the riparian area, the sites were usually predominantly mature Engelmann Spruce forest (Picea engelmannii), with varying amounts of Lodgepole pine (Pinus contorta) (Fig. 5). Less than 2% of the sites had an "open" measurement for surrounding vegetation (see Table 3).

Figure 5. "Western Flycatcher" site along the Forestry Trunk Road north of Waiparous.

 

TABLE 3. Habitat type¹ surrounding the "Western Flycatcher" sites.

¹Each site has four possible bordering habitat types, one in each of the four cardinal directions.

 

A north-facing slope was the best predictor of Western Flycatcher presence (Fig. 6). Ninety-two percent of the sites had either a cliff or an incline with cliff-like aspects to it. North-facing cliffs were predominant (Table 4). The median of the slope heights was 21 m (range=5 m - 95 m, N=36) (Fig. 7). Slope angle ranged from 30°-90° with an average of 64°. The coefficient of variation is 0.26 indicating a relatively low spread of angle values around the mean.

 

Figure 6. "Western Flycatcher" sites on Livingstone River.

 

TABLE 4. Direction the predominant slope/cliff
faces in "Western Flycatcher" sites.

Figure 7. Frequency of slope heights in the territories of "Western Flycatchers"

 

The slope had varying vegetation depending on the composition of the substrate and severity of the incline. Unstable slopes were lightly vegetated but rocky cliff faces supported spruce, pine, juniper and some deciduous shrubs in sheltered areas. Often, the cliffs were bordered by unstable slide areas. Over 40% of the slopes had "moderate" vegetation while 30% had little and 30% had dense vegetation.

The slope could be interpreted as a transition between riparian and coniferous areas. The vegetation on top of the slope was invariably coniferous and similar to the regional vegetation.

Many of the slopes descended straight to the water but most had some shoreline or beach area with vegetation between the slope and the water (Table 5). This vegetation was different from that on and above the slope and the surrounding area. Nearly 40% of the vegetation below the slope was deciduous bushes and shrubs, primarily alder (Alnus spp.) and willow (Salix spp.). Large numbers of Balsam Poplar stands could be found adjacent to the streams opposite the cliffs.

TABLE 5. Dominant habitat type below the slope/cliff.

Conifers were the most common trees counted in the 10 m radius transects, followed by willows and aspens (Table 6). The transects showed the sites tended towards larger, coniferous trees, with spruces 10-30 cm dbh (diameter at breast height) being the most common (Table 7). Over 80% of the sites had either size class 3 or 4 spruces. The abundance of both conifers (surrounding vegetation) and deciduous trees and shrubs (riparian vegetation) within the transects indicates a sharp transition between the riparian and surrounding areas (Table 8). With respect to the combined species, size class 3 trees (11-20 cm dbh or 62-124 cm circumference) predominated indicating a relatively dense mature forest (Fig. 8).

 

TABLE 6. Average number of trees (or stems) of different taxa per site.

TABLE 7. Mean number of trees (or stems) per site by taxa and size class.

TABLE 8. Mean number of trees per transect

Figure 8. Distribution of tree sizes counted in 10 m radius transects in "Western Flycatcher" sites. Error bars indicate standard error.

 

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