Boyce Thompson Arboretum IBA is located 3 miles west of Superior. It includes the north slope of Picketpost Mountain, foothill canyons and ridges, and two intermittent creeks. Boyce Thompson Arboretum is the steward for this IBA. Information about the arboretum and events can be found at http://arboretum.ag.arizona.edu/
The 100-acre tract of botanical gardens open to the public is used for education, research, and land conservation, and low-impact recreation (such as strolling, picnicking, picture-taking, animal-watching, etc.). Most of the IBA's vegetation (>85%) is typical of the Arizona Upland Subdivision of the Sonoran Desert. Several plant associations associated with differences in topography and soils produce a diverse flora. Marsh-fringed Ayer Lake and intermittently flowing Queen and Arnett Creeks provide traces of wetland and riparian habitat. Rugged Magma Ridge and the slopes above the creeks stand in stark contrast to the lush vegetation within the park.
The IBA formal dedication event was in conjunction with International Migratory Bird Day on May 2007. Over 90 people participated in the early morning bird walks and the outdoor dedication in the garden. Dr. Carl Tomoff of Prescott College delighted the crowd with stories of the birds to be found at this most enchanting of our Arizona IBA's. More information can be found at http://arboretum.ag.arizona.edu/
Of at least 275 species recorded in the IBA since the mid 1970s, 62 species of Special Conservation Status in Arizona include: Federally Endangered or Threatened (2 species), AZ Game & Fish State Threatened (15 species), AZ Partners in Flight Priority (APIF) Species (24 species), Audubon WatchList in Arizona (7 species), and U.S.F.W.S. Birds of Conservation Concern (14 species).
The Arboretum provides important habitats and resources throughout the year, not just during a particular season, thus qualifying the site under the landbird criteria, "exceptional seasonal diversity of landbirds." Probably at least partly due to the "oasis"-like nature of the area, at least 78 accidental species (5 or fewer records) and 48 casual species (more than 5, but not occurring annually) have been recorded since 1976. Many of these birds were spring and/or fall transients, but some were noted during summer and others during winter. The site's attractiveness to vagrants and uncommon visitors is likely to continue, as exemplified by the presence of an Olive Warbler (previously undocumented here) during the inaugural Superior Christmas Bird Count held on January 4, 2004.
Populations of some transient species periodically reach relatively high numbers, particularly on "fall-out" days. On occasion, dozens of some species and scores of others have been noted during spring and fall migration periods, thus qualifying the site also under the criteria "Outstanding Landbird stopover Site."
This site also meets two other Arizona IBA criteria:
1) Special Conservation Status Species in Arizona, including (frequent to common): breeders (total: 12): 7 riparian species (listed below), plus Purple Martin (APIF), Elf Owl (Audubon-Yellow listed), Gilded Flicker (Audubon-Yellow listed), Costa's Hummingbird (Audubon-Yellow listed), and Crissal Thrasher (USFWS) [and also including possibly "uncertain nesting status" species: Golden Eagle (USFWS) and Prairie Falcon (USFWS), also vagrant breeding Varied Bunting (USFWS)]; migrants (total: 5): 2 riparian species (listed below), plus Gray Flycatcher (APIF), Black-throated Gray Warbler (APIF, USFWS), Brewer's Sparrow (APIF, Audubon-Yellow listed); and wintering species: 2 riparian species (listed below).
2) Rare or unique habitat, that hold important species or species assemblages largely restricted to a distinctive habitat or ecological community type. The Arboretum's low-elevation riparian habitat is an exceptional example of this rare habitat in Arizona, and supports "riparian obligate" (or riparian dependent) species and species of special conservation status, breeders: Common-Black Hawk (APIF), Lucy's Warbler (Audubon-Yellow listed), Northern Beardless-tyrannulet (USFWS), Bell's Vireo (Audubon-Red listed), Broad-billed Hummingbird (USFWS), Abert's Towhee (Audubon-Yellow listed), and Yellow Warbler (USFWS), also noteworthy summer visitor, the Yellow-billed Cuckoo (APIF); migrants (frequent to common): Southwestern Willow Flycatcher (Endangered), MacGillivray's Warbler (riparian dependent) (APIF) , and wintering species: Red-naped Sapsucker (riparian dependent) (APIF), and casual species, Gray Catbird (riparian dependent) (State threatened 1996).
This combination of high species richness and occasionally high numbers is ecologically significant and provides a remarkable opportunity for visitors to observe and learn about birds. The aesthetically beautiful setting of the area is a bonus.
Issues of minor concern include: necessity to maintain fencing to restrain cattle entry and to discourage hunting; expansion of mineral extraction activities on nearby Tonto National Forest lands; flooding with its deleterious removal of riparian vegetation; reduction of stream flow from upstream use; potential for wild fire in desert scrub.
The 349-acre arboretum is owned by Boyce Thompson Southwestern Arboretum, Inc. (329 acres), the University of Arizona (20 acres), and is cooperatively managed by BTSA, UA, and Arizona State Parks. Access to areas beyond the botanical gardens is arranged through Arboretum management personnel.Arnett Creek and Pickett Post Mountain are United States Forest Service lands (2,722 acres).
Most of the IBA's vegetation (>85%) is typical of the Arizona Upland Subdivision of the Sonoran Desert. Several plant associations associated with differences in topography and soils produce a diverse flora. Marsh-fringed Ayer Lake and intermittently flowing Queen and Arnett Creeks provide traces of wetland and riparian habitat. Rugged Magma Ridge and the slopes above the creeks stand in stark contrast to the lush vegetation within the park. Saguaro (Cereus gigantea), Foothill and Blue Palo Verde (Cercidium microphyllum and C. floridum), Ocotillo (Foquieria splendens), and a variety of cacti and small shrubs cover the uplands. Mesquite (Prosopis juliflora), Catclaw Acacia (Acacia greggii), Burrobush (Hymenoclea monogyra), and Desertbroom (Baccharis sarothroides) line xeric washes, while Goodding Willow (Salix gooddingii), Fremont Cottonwood (Populus fremontii), Velvet Ash (Fraxinus velutina), and Netleaf Hackberry (Celtis reticulata) cluster along wetter drainage ways.
The 100-acre tract of botanical gardens open to the public is used for education, research, and land conservation, and low-impact recreation (such as strolling, picnicking, picture-taking, animal-watching, etc.).
Access to areas beyond the botanical gardens is arranged through Arboretum management personnel.