Eastern Bluebirds in Illinois

Eastern Bluebirds are summer residents in Illinois, arriving shortly before nesting begins in April and leaving after the young are independent. Through the season they feed on grasshoppers, crickets and beetles; caterpillars and spiders.

Humid continental, grading from the Lake Michigan shore and prairie north to the forested Shawnee Hills in the south.

Across Illinois, bluebirds typically nest from April–August. Nest site: secondary cavity nester — old woodpecker holes and nest boxes in open habitat. Females lay 2–7 eggs, incubate for 11–19 days, and young leave the nest after 15–20 days.

Hot, humid summers; much of the state is farmland, so backyard native plantings matter.

• Have boxes cleaned and mounted before March — bluebirds begin prospecting ahead of egg-laying.
• Use a 1 1/2 in round (1 9/16 in for Mountain/Western overlap) entrance on a 5 × 5 in floor, mounted 4–6 ft on a baffled pole.
• Fit a pole baffle or hole guard; ventilation gaps and drainage holes are essential.
• Clean out old nests after each brood and again after August.

Of the regional native plants we track for Illinois, these 8 provide food or cover bluebirds use:

Bluebirds hunt from perches over short grass. Put mealworm feeders in the open, near a low perch, and offer small amounts at the same time each day.

• Best foods: Live or dried mealworms, Suet nuggets / insect-suet dough, Chopped native fruit.
• Avoid: Loose seed mixes — bluebirds rarely eat seed.
• In Illinois's summer: offer water and insect foods; natural food is abundant.

Full diet breakdown for bluebirds · Best feeder for bluebirds