By Chris Kirkpatrick and Courtney J. Conway

We studied reproductive success and habitat associations of montane forest birds within four study sites located in high-elevation (>2,000 m) forests of the Santa Catalina Mountains, Arizona from 2004-2007. We focused our research on ground-nesting forest birds because they represent some of the most common bird species within our study system and provide high-quality data via easy access to nests during nest monitoring efforts. We also examined the effect of a recent wildfire on the montane forest bird community by determining population trends of montane forest birds following a wildfire that burned portions of our four study sites in 2003. The wildfire was a low- to moderate severity surface fire, so we concentrated our fire research on ground-nesting forest bird species, particularly Red-faced Warblers (Cardellina rubrifrons) and Yellow-eyed Juncos (Junco phaeonotus), because nests of these species were most likely to be affected.

We detected a total of 34 montane forest bird species during annual point-count bird surveys. Red-faced Warblers, Cordilleran Flycatchers (Empidonax occidentalis), Yellow-eyed Juncos, Warbling Vireos (Vireo gilvus), House Wrens (Troglodytes aedon), Western Tanagers (Prianga ludoviciana), Black-headed Grosbeaks (Pheucticus melanocephalus), Yellow-rumped Warblers (Dendroica coronata), American Robins (Turdus migratorius), and Mountain Chickadees (Poecile gambeli) were the ten most frequently detected species. Yellow-eyed Juncos, House Wrens, Black-headed Grosbeaks, and Mountain Chickadees increased in relative abundance within our study area after the 2003 fire. A closer look at the ground-nesting bird species within our study area revealed that Yellow-eyed Juncos and Red-faced Warblers were the two most common ground-nesting birds and density of Yellow-eyed Juncos (1.2 males/ha) was twice as great as for Red-faced Warblers (0.6 males/ha). Compared to random sites, most Red-faced Warblers and Yellow-eyed Juncos selected nest-sites close (≤50 m) to drainage bottoms in stands of montane riparian forest characterized by more saplings and small trees (red-faced warblers), more shrubs and less canopy cover (Yellow-eyed Juncos), and more ferns, forbs, brush, and small woody debris (both Photo by Jim Rorabaughspecies). Although Red-faced Warblers and Yellow-eyed Juncos nested in close association in montane riparian forest, the two species appear to coexist by selecting available nest-sites with different environmental features at both the macrohabitat and microhabitat scales. Both species avoided nesting in areas that were burned by a recent low-severity surface suggesting short-term negative effects of fire for breeding populations of Red-faced Warblers and Yellow-eyed Juncos. Moreover, daily nest survival declined substantially immediately following the Aspen wildfire for both species. Montane riparian forest in the southwestern U.S. appears to provide important breeding habitats for Red-faced Warblers, Yellow-eyed Juncos, and numerous other montane forest bird species. However, little research or conservation planning has been directed toward montane riparian forest in the region, even though this forest type is limited in its areal extent (<1% of the total land mass in the Sky Island region of Arizona) and increasingly threatened by disturbances such as fire.