My neighbor is a very active and observant bird watcher and on my daily dog walk he told me to take a look at the stand of Chinese pistache trees down the block. “They're full of red berries and the little birds are feasting on them,” he told me. “You might even see a yellow Wilson's warbler; they're migrating now.” I didn't spot any warblers in the trees, but did see about 30 noisy finches and sparrows flitting around the berry clusters.

I had never noticed that those three trees were loaded with berries and full of small birds in fall. Maybe that's because almost all the trees in my neighborhood are male varieties; it's rare to see female or flower and fruit-bearing landscape trees in any neighborhood.

The rationale for planting only male trees has been that female fruit, nut and seed-bearing trees trees create litter that can make a mess on sidewalks, patios and cars. They can also attract rats, squirrels and other vermin. Male trees aren't as messy, but they do produce pollen – one of the main reasons allergy problems have increased in recent years. Nurseries often stock only male trees.  

According to a report on the Audubon website, the population of birds in North America is nearly three billion fewer than in 1970. Other sources state that 90% of the decline in the U.S. bird population is in just 12 bird families, including small warblers, sparrows and finches, seed and berry-eating birds that are very common in our urban neighborhoods. The decline is driven by climate change, heat stress, urbanization and the loss of agricultural land. Some birds – including crows, riparian black Phoebes and Anna's hummingbirds – have been better able to adapt to changing conditions, unlike desert birds whose populations have plummeted. 

We try to encourage home gardeners to plant bee- and pollinator-friendly gardens that include a variety of flowering plants that bloom at differing times in order to provide a constant source of pollen and nectar for beneficial insects (and hummingbirds). We might also stress the need to plant a variety of flowering trees and bushes in home gardens, which will provide shelter, nest-building materials, habitat, seeds, fruit, sap and insects for birds throughout the seasons.

Native trees, which will attract and feed native birds, are the obvious first choice, but finding them can be difficult. Many new housing developments have very limited yards or green space and lack parking strips where trees can be planted, so size at maturity is another factor. Nursery labels often don't indicate whether trees and bushes are native, whether they produce seed that is edible for birds, or when fruit and seed production will take place. However, more local nurseries and garden centers are setting aside space for and emphasizing native plants, and their staff is becoming more knowledgeable.

The most bird-friendly Central Valley gardens would include a few smaller evergreen conifers, one deciduous fruit or flowering tree, two or three groupings of perennial seed and berry bushes as well as flowering annuals and perennials that bloom over the length of the growing season and hold seed through the winter.

Sources:

Plant Native Trees That Attract Birds, Birdsandblooms.com, Jan. 21, 2022   

Climate change, urbanization drive major declines in birds, UC Berkeley News, Feb.22, 2023

North America has lost more than 1 in 4 birds in the last 50 years, new study says, Audubon, Sept. 19, 2009

"The Allergy-Fighting Garden," Thomas Leo Ogren, 2015, Ten Speed Press, ISBN: 978-1-60774-491-7