Figure 7. Willow Flycatcher using a
spruce perch as a display post
The Willow Flycatcher is a sparrow-sized bird with a medium-dark, brownish olive to grayish olive back and head, two light wing-bars and light underparts with a brownish olive breast band and slight yellow wash to the vent (Pyle 1997). Like all the members of the genus Empidonax, the Willow Flycatcher is insectivorous and catches insects on the wing. Prescott and Middleton (1988) found Willow Flycatchers to have a strong preference for Diptera (true flies) and to a lesser extent, Hemiptera (true bugs).
The only reliable method of identifying Empidonax flycatchers in the field is by their songs. This is especially critical when trying to distinguish the visually identical Willow and Alder Flycatchers. Both male and female Willow Flycatchers have been found to sing (Seutin 1987). The standard advertising song of the Willow is a fitz-bew (Fig. 4) but will also sing a wheezy fizz-bew (Fig.5). It will also emit a sharp, dry creet (Fig. 6) as well a zbew. Many sources have noted that the Willow begins to vocalize much earlier in the day than the other bird species within its habitat (Bent 1942, Weydemeyer 1973).
| Figure 4. Sonogram of the fitz-bew song produced by the Willow Flycatcher. (Macromedia Flash plug-in required) or Click here to listen to WAV file (44 kb) |
| Figure 5. Sonogram of the fizz-bew song produced by the Willow Flycatcher. (Macromedia Flash plug-in required) or Click here to listen to WAV file (42 kb) |
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Figure 6. Sonogram of the creet call produced by the Willow Flycatcher. (Macromedia Flash plug-in required) or Click here to listen to WAV file (42 kb) |
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Figure 7. Willow Flycatcher using a
spruce perch as a display post
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In Alberta, vocal displays are often performed from tall spruces within the willow habitat (Fig. 7). These spruces offer an unobscured view of the bird’s territory. Where spruce is not present, bare willow branches are often used and in some sites the Willow Flycatchers use overhead powerlines as perches. These display perches are also used to initiate foraging sallies.
The Willow Flycatcher arrives on its breeding grounds in Alberta in late May (Pinel et al.1993, McGillivray and Semenchuk 1998). Males have been found to arrive up to two weeks earlier than females to set up territories (Sedgwick and Knopf 1992). The sites we found supported an average of two pairs. In our study, territories were not mapped but Willow Flycatchers responded to playback by approaching the source of the sound from distances up to 200 m. Prescott and Middleton (1988) found territories of Willow Flycatchers in Ontario to average 0.3 ha. McCabe (1991) reports several studies which found Willow Flycatcher territories to be between 0.1 ha – 0.44 ha.
The nests are built at a fork in a bush. McCabe (1991) found if the habitat is all willow, it will be selected as a nest site but if there are other bushes, they will be chosen instead. The height of the nest above the ground is usually between 1.0 and 1.5 m (Campbell et al. 1997). Three to four eggs are laid with an incubation time of approximately 16 days (Campbell et al. 1997). Feeding of the nestlings has been found to be performed equally by both parents (Ettinger and King 1980). Polygyny has been reported in Willow Flycatchers (Prescott 1986, Sedgwick and Knopf 1991). Nest success for Alberta has not been studied but in British Columbia, nest success was 28% (Campbell et al. 1997). Fledging occurs after about two weeks (McCabe 1991). The Willow Flycatcher is believed to leave the province for its wintering grounds in August (McGillivray and Semenchuk 1998).