Materials and Methods

Study Area

To determine the census area, we reviewed previous records of "Western Flycatchers" within Alberta from the Provincial Museum of Alberta (PMA) collection, the Federation of Alberta Naturalists (FAN) Birdlist database, which includes the records from the Breeding Bird Atlas project and Pinel et al. (1993). As a result, we established a census route north from Waterton Lakes National Park to Jasper National Park and east from the British Columbia border to Cadomin in the north and Sundre in the south. The census area encompassed all the documented sightings of the "Western Flycatcher" in Alberta. This was a large area to cover in one field season, consequently, census routes were restricted to roads, major trails and surrounding areas a short hike from road access. Without doubt, many suitable areas for this species exist away from roads in the foothills and mountains.

The Rocky Mountains and Foothills Regions are biophysical units of Alberta (Alberta Natural Heritage Information Centre 1999). The Rocky Mountains form the western boundary of southern Alberta and range from 1000 m to 3700 m. This regions is dominated by primarily coniferous forests of various species of pine (Pinus spp.) and spruce (Picea spp.). The Foothills are a transition region between the Rocky Mountains and the Boreal Forest, Aspen Parkland and Grassland regions to the east. Forests tend to be mixed deciduous and coniferous with species composition dependent on elevation.

 

Census

Due to the short period of time "Western Flycatchers" are on territories singing (Cannings pers. comm.), we censused in May and June and returned to each site later in the season to assess habitat.

Censusing was conducted from 4:00 am to 1:00 pm between 25 May and 4 July 1999. The "Western Flycatcher" sings vigorously early in the breeding season and early in the day (Cannings, pers. comm.). Because spring arrival dates in Alberta are not well known and the preferred range of this species easily affected by inclement weather, we were not comfortable assuming that the absence of the species in late May or early June meant that it does not breed in the censused area. To minimize the risk of missing late arrivals, we began censusing in extreme southwestern Alberta and worked north. A return trip to Waterton Lakes National Park in June allowed us to confirm the validity of earlier observations.

Potential sites were selected on the basis of previous records, and habitats that contained the features known to attract "Western Flycatchers." Upon arrival at a site, we began taped playback of song, unless there was a male already singing. Playback was performed with intervals of one minute playing and one minute of silence for about 10 minutes. It was necessary to spend the minimum of 10 minutes because the high level of background noise from streams in the habitat makes playback and hearing the birds difficult. Most sites were located along fast-moving streams and sometimes near rapids and waterfalls. Once a bird responded to the playback, we would obtain the latitude, longitude and elevation of the site using a Garmin 12XL GPS unit. The location of the site, other bird species detected and a brief habitat description were also noted. Each site was then photographed.

 

Habitat Measurement

Categorical Habitat Assessment

Once a singing male was determined to be defending a territory, we recorded a variety of categorical and quantitative variables. Water on the site was classed as either: (1) standing water, (2) slow-moving stream or river or (3) fast-moving stream or river. We measured the stream and riparian zone (first major break in slope) to the nearest metre using a Bushnell Yardage Pro 800 range finder or by sight, if the stream was small.

To determine if the habitat surrounding the site was distinctive, in each of the cardinal directions, we classified it into either: (1) coniferous forest, (2) deciduous forest, (3) mixed forest (coniferous dominated), (4) mixed forest (deciduous dominated), (5) riparian shrubs, (6) stream/river (7) moss or grass, or (8) bare.

A slope or cliff was characteristic of all "Western Flycatcher" sites. We used the Bushnell range finder to determine the height of the cliff and recorded the direction it faced. We then used a Suunto clinometer to get an approximate slope angle. Depending on the slope of the incline, we classed it into either: (1) slope (30°), (2) steep incline (30-60°), (3) steep incline with cliff aspects (30-60° with some areas > 60°) or (4) cliff (> 60°). Because slopes are known nesting sites for Western Flycatchers, we recorded the dominant vegetation for the top and bottom of the slope. Finally, the type and density of vegetation on the slope was noted.

Quantitative Assessment

Simply recording vegetation categories (e.g., coniferous forest) tells us little about the maturity of the surrounding vegetation or its density. To provide a measure of vegetation maturity, we counted the number, size (see Table 1) and species of trees in a 10 m-radius circle in the riparian or top-slope habitat that was frequented by the birds. The centre of the circle was picked at random within the riparian area.

 

TABLE 1.

Data Analysis

Data from the field sheets were entered into a computer and assessed univariately and graphically. We performed the analyses using Microsoft Excel 97 and SPSS 7.5. When variables were approximately normally distributed, parametric measures of central tendency and spread were used.

 

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