Well-selected trees nourish and protect wildlife. Which species among the following three would be the best tree for a native-plant wildlife garden?
For feeding and protecting the wildlife in your backyard, it's hard to beat Eastern Red Cedar (or another species in the genus Juniperus that is native to your area). Eastern Red Cedars and other junipers are evergreen, and their dense branches provide excellent cover and protection from the elements year-round. A cluster of junipers can even be dense enough to shelter large animals like Mule Deer and Pronghorn antelopes. Junipers can harbor hibernating bats and other small mammals in winter; nesting birds in spring and summer (Cooper's Hawks, Mountain Bluebirds, Northern Flickers, Lewis's Woodpeckers, and many others); and roosting owls at any time. Twenty-seven different bird species have been recorded as nesting, in open nests or cavities, in Western Juniper (Juniperus occidentalis). In addition to cover, Juniperus species provide food. Many bird species, including the Cedar Waxwing -- which was named for this preferred food -- eat juniper berries or cones. Quail, grouse, turkeys, jays, woodpeckers, and thrushes are some of 90 bird species known to feed on Eastern Red Cedar. They are joined by rabbits, foxes, raccoons, mice, coyotes, and deer. Mule Deer, Elk, and Pronghorns browse on the foliage of Western Juniper. The Juniper Hairstreak and several other species of hairstreak butterflies utilize junipers as host plants for their caterpillars.
Native oaks are superb wildlife plants as well, although perhaps a bit less versatile than junipers. They provide good nesting sites for birds and squirrels, and they tend to retain their leaves well into fall, providing extra cover and protection. Acorns are staples for many species of birds and mammals -- from jays to squirrels to black bears -- and the twigs, leaves, and bark feed others.
The Horse-chestnut is a European species, planted for its beautiful spring flowers. Native Aesculus species, known as buckeyes, have the same showy flowers -- and all species have poisonous nuts. One native species, the Red Buckeye (Aesculus pavia) of the southeast, is a wonderful hummingbird plant, but for the most part buckeyes are not particularly attractive to wildlife.
In addition to junipers and oaks, there are many other good native North American trees for the wildlife habitat. Native pines provide cover for owls and chipmunks, sap for sapsuckers, nesting cavities for woodpeckers, and pine nuts for many birds and mammals. Native fruit and nut trees, including cherries (Prunus), walnuts (Juglans), dogwoods (Cornus), hackberries (Celtis), and others are all excellent and handsome choices.
Of course, all of this depends on a host of variables like your climate zone, the size of your landscaping area etc...but I throught I'd give a few suggestions.