Fueled by runoff from the nearby mountains, Queen Creek cuts through the Arboretum's bottomlands. Like many desert streams, Queen Creek is intermittent, flowing for a short distance and then disappearing beneath the sand. Along the creek, water-loving trees, including Fremont cottonwood, Arizona ash, black willow and Arizona black walnuts create a habitat strikingly different from the surrounding desert. Hardwood trees provide dense cover for shade plants in addition to shelter and food for many mammals, birds and reptiles.
In the desert, a stream or waterhole is a magnet for animals. The Arboretum's irrigated gardens and protected grounds provide a haven and constant food supply for local wildlife. Over 300 species of mammals, birds, reptiles and amphibians are found in the Arboretum. Abundant but often unseen insects, spiders and scorpions are also part of the Arboretum's natural ecosystem.
Seeking shelter during the heat of the day, many of the Arboretum's free-roaming inhabitants are not always evident. Snakes, tortoises and toads usually venture forth at dawn or dusk. Lizards, such as the desert spiny lizard may be seen basking in the sun during the day.
You may be interested in the checklist of birds that frequent the arboretum grounds.
The bird fauna of the Arboretum is extensive. Birds are important to the desert plant community. Many desert plants rely on insects, birds, bats, rodents and other animals to pollinate their flowers and to disperse their seeds. More than 250 species have been recorded in the 'Birds of the Arboretum Checklist'. Gambel's Quail, Canyon Wren, Curve-Billed Thrashers, and Black Throated Sparrows are among the most abundant species, and dozens of other lower Sonoran birds can typically be found on a productive day's bird walk. The extensive irrigated areas of native and exotic trees and shrubs provide food and shelter for countless winter visitors and transients.