While many visitors try to get a glimpse of the Great Horned Owl family which nests in the canopy over the Great House ruins, observers are much more likely to see Rock Pigeon, Eurasian Collared-Dove, and European Starling there. Best birding is to be had early in the morning at the picnic area north of the visitor center. In addition to mesquite, ironwood, and palo verde trees, that area includes over a dozen small garden plots featuring native plants. As the Monument is not open until 9am, you may want to examine the gardens prior to viewing the Great House. The Monument closes at 4pm.

Among USFWS-designated Sonoran Desert Birds of Conservation Concern, Gila Woodpecker, Gilded Flicker, Verdin, and Curve-billed Thrasher have been reported on multiple lists.

Casa Grande Ruins National Monument grounds are a rectangle 1 mile (east-west) by 0.75 mile (north-south), covering 472.5 acres, of which about 5 acres is open to the public.  So this is a very small hotspot, as far as federal lands hotspots in the American West go. The only entrance to the hotspot is off Arizona Boulevard (AZ- 87), from which the visitor center is about three-quarters of a mile west through an almost treeless, creosote-dotted habitat of short desert grasses. Parking on this short entrance road, let alone getting out to wander the grounds, is prohibited. There is no open water – not even an ephemeral playa – on the grounds. The Pima Lateral forms the south boundary of the Monument, and though Kildeer may be sometimes heard there when water flows through the canal, the levee is fenced with is no birder access. Despite the Gila River bed being less than a mile and a half north, it is typically dry, water having been diverted upstream into such canals.