Restoration Potential: Still a relatively common species. Should benefit from forest and riparian management that maintains stands with shrub and sapling understories, snags, and intact streambanks.
Preserve Selection and Design Considerations: There is little known about landscape relationships. In a study in a northwestern California Douglas-fir forest, western flycatcher (EMPIDONAX DIFFICILIS) avoided edges, yet did not respond negatively to forest fragmentation. Positive association to the proximity and length of clearcut edges and positively correlated with stands that were more insular, or contained more clearcuts and total edge (Rosenberg and Raphael 1986). Given cordilleran's association with riparian habitats throughout most of its range, the species may be adapted to patchier habitats, but its relationships to area, surrounding landscapes, and types of edge need to be further studied.
Management Requirements: Should benefit from maintaining moist montane riparian and forest habitats with moderate to dense canopies, shrub or sapling understories, snags, and intact streambanks, especially in mountain ravines and canyons. Overall, there is little specific information available on the effects of human activities and habitat alterations on this species. Until recently, many management studies overlooked EMPIDONAX flycatchers or lumped them together due to the difficulty of distinguishing this suite of species. Recent breeding bird studies that use trained observers more often detect cordilleran flycatcher, but information on management requirements for the species is still slim. There is a large body of literature, however, on human impacts on riparian habitats which can provide direction for maintaining the integrity of these ecosystems. For example, see Ohmart (1994) or Ohmart and Anderson (1986) for general overviews, and Idaho Partners in Flight (1998) for riparian habitat management guidelines.
TIMBER HARVEST: Harvesting in riparian corridors could be detrimental, and leaving a buffer between riparian habitats and harvest units would likely benefit the species. A summary of silvicultural studies suggests that abundances are similar in partially cut forests and in uncut forests (Hejl et al. 1995). A number of studies, however, show declines with more extensive timber harvest. In an Arizona mixed coniferous forest, for example, density declined 50 percent four years after timber harvest (most noticeably on south aspects) where the prescription included a mix of individual tree selection, group selection to reduce basal area 30 percent, and clearcut patches, but left steep slopes unharvested (Scott and Gottfried 1983). In northern Arizona ponderosa pine, uncut stands or moderately thinned stands over severely thinned stands (Szaro and Balda 1979, Brawn and Balda 1988). In the Northern Rockies, it is more likely to occur in areas with greater numbers of snags (Hutto and Young 1999). In northwestern California, observations of western flycatcher (E. DIFFICILIS or OCCIDENTALIS unknown) in a mixed forest dominated by Douglas-fir (PSEUDOTSUGA MENZIESII) and ponderosa pine (PINUS PONDEROSA) showed that density declined an average 80 percent where overstory removal reduced total tree density by 75 percent and basal area by 80 percent (Franzreb and Ohmart 1978). In western Mexico tropical deciduous forest, abundance was significantly and dramatically less in short second-growth that had been deforested for livestock production than in undisturbed forest, and somewhat less abundant in tall second-growth than in undisturbed forest (Hutto 1992).
Studies of Pacific-slope flycatcher (EMPIDONAX DIFFICILIS) show the species prefers old forests over younger stands (Raphael et al. 1988, Carey et al. 1991, Manuwal 1991). In an Oregon Cascades study, the species favored old stands and areas with decayed logs, fern and deciduous shrub cover, western hemlocks (TSUGA HETEROPHYLLA) and very large western redcedar (THUJA PLICATA); the authors suggested that older stands probably best meet the species need for open flying space for feeding (Gilbert and Allwine 1991). In mature, unmanaged forest stands, average abundances are slightly higher along streamsides than in upslope stands, but not significantly so (McGarigal and McComb 1992). These associations need to be examined for the cordilleran flycatcher as well.
GRAZING: Overgrazing can cause heavy damage to the understory of riparian habitats and delay regeneration (Ohmart 1994), which would eliminate the habitat. Often nests in low streambanks, so nesting habitat can be destroyed when livestock are allowed to break down streambanks and nests may be vulnerable to trampling (Hutto and Young 1999). Livestock presence may also encourage brown-headed cowbirds (MOLOTHRUS ATER), a brood parasite.
Management Research Needs: More study is needed of the effects of timber harvest, grazing, and other habitat alterations, particularly in relationship to productivity and survivorship. Winter ecology, habitat preferences, and threats need investigation. Examination of area requirements, effects of fragmentation, spatial juxtaposition of habitat other aspects of landscape ecology are needed. Further study of brood parasitism rates in relation to human alterations of habitat and behavioral response to parasitism is needed.
Biological Research Needs: Most aspects of demographics, life history, and ecology need better study given the recent split between cordilleran and Pacific-slope flycatcher. Need information on details of habitat relationships; wintering ecology; migratory patterns and location of wintering grounds for migratory populations; survivorship; diet, nutrition and energetics; disease, nest predation and other sources of mortality; rates of and response to brood parasitism; site fidelity; territory size; limiting factors. Need information on breeding biology; wintering ecology; migratory patterns and location of wintering grounds for migratory populations; life span and survivorship; physiology; diet, nutrition and energetics; disease, nest predation and other sources of mortality; rates of and response to brood parasitism; philopatry, territory size; details of habitat relationships; limiting factors.
