You’re going to find the best bird diversity in native vegetation, no doubt about it. Native plants have insects (read: bird food!), due to relationships that have been evolving in this place for a very long time. Non-native plants are often free of such insects, and therefore free of birds. But in an urban area like Tucson, we’re stuck with lots of non-native vegetation, and to increase our species count on the Christmas Bird Count, it pays to learn how to selectively check it for birds. Some, like the non-native ash trees (Fraxinus sp.) in so many apartment complexes, are utterly birdless. Others might actually be worth checking carefully.
Kurrajong, Brachychiton populneus, in the mallow family, is an Australian native that Red-naped Sapsuckers (very common in the native oak woodlands at higher elevation around us, but scarce in the Tucson Valley) seem to find a reliable source of tree sap. The sapsuckers are very quiet, but you can look carefully up into each tree and perhaps find one.
The SEINet data portal lists as many as 17 species of Eucalyptus in Pima County. Red River Gum (E. camaldulensis) and Coolibah (E. microtheca) are the two most planted and can have birds if they are blooming, including hummingbirds, tanagers, orioles, and warblers. Here’s a Coolibah which can also have Red-naped Sapsucker.
Here are two blooming Eucalyptus species that I haven’t identified yet, which I recently saw at the Vista del Norte mobile home park in north-central Tucson. Rare warblers to look for in these trees could be Cape May, Northern Parula, and Tennessee. In fact, one blooming Eucalyptus (probably a Red River Gum) in this residential area had Arizona’s second winter record of Calliope Hummingbird.
These trees seem to bloom erratically and unpredictably, and information on where trees are blooming is valuable. Go birding in your area and let us know if you are finding blooming eucalyptus.