Tree Swallows in California

Tree Swallows live in California all year. Wet, mild winters are the green season — the busiest time at coastal feeders as sparrows and hummingbirds settle in. That makes the cold months the time your yard matters most to them: their winter diet shifts toward bayberry and wax myrtle fruit.

Mediterranean along the coast and Central Valley, alpine in the Sierra Nevada, and desert in the southeast.

Across California, tree swallows typically nest from April–June. Nest site: nest box or tree cavity lined with feathers. Females lay 4–7 eggs, incubate for 11–20 days, and young leave the nest after 15–25 days.

Dry summers with little rain from May to October; water and summer-blooming natives matter more than extra seed.

• Have boxes cleaned and mounted before March — tree swallows begin prospecting ahead of egg-laying.
• Use a 1 1/2 in entrance on a 5 × 5 in floor, mounted 5–10 ft.
• Fit a pole baffle or hole guard; ventilation gaps and drainage holes are essential.
• Clean out old nests after each brood and again after June.

Of the regional native plants we track for California, these 8 provide food or cover tree swallows use:

Tree swallows readily take bluebird-style nest boxes; mount boxes in pairs 15–25 ft apart to share with bluebirds.

• Best foods: Crushed eggshells in spring.
• In California's winter: Wet, mild winters are the green season — the busiest time at coastal feeders as sparrows and hummingbirds settle in.

Full diet breakdown for tree swallows · Best feeder for tree swallows