Bill Walker: Mission San Xavier
Bill Walker: Mission San Xavier
Bill Walker: Varied Bunting
Bill Walker: Bighorn Sheep (captive)
Bill Walker: Butterfly
Bill Walker: Northern Cardinal
Bill Walker: Rufous-winged Sparrow
Bill Walker: Canyon Towhee
Bill Walker: Violet-crowned Hummingbird
Bill Walker: Thick-billed Kingbird
Bill Walker: Mesquite
Bill Walker: Plumbeous Vireo
Bill Walker: Elegant Trogon
Bill Walker: Botteri's Sparrow
Bill Walker: White-line Sphinx Moth
Bill Walker: Lucifer Hummingbird
Bill Walker: Northern Beardless-Tyrannulet
Bill Walker: Summer Tanager (formerly mistitled)
Bill Walker: Mississippi Kite
Bill Walker: Ocotillo