Colorado · Summer breeder

Tree Swallows in Colorado

When tree swallows are present in Colorado, when they nest, which native Colorado plants feed them, and how to host them in a USDA 3a–7b yard.

Swallows (Hirundinidae)Tree SwallowTachycineta bicolor

Status in Colorado: Summer breeder
Nesting window: May–June
Broods: 1 per season
Hardiness zones: USDA 3a–7b
Nest box: 1 1/2 in hole, 5 × 5 in floor, 5–10 ft

When to expect tree swallows in Colorado

Tree Swallows are summer residents in Colorado, arriving shortly before nesting begins in May and leaving after the young are independent. Through the season they feed on flies, mayflies and dragonflies.

Semi-arid high plains in the east and the Rocky Mountains through the center, with most backyards between 5,000 and 7,000 ft.

Nesting in Colorado

Across Colorado, tree swallows typically nest from May–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.

Warm, dry days and cool nights; afternoon storms are common in July and August.

Have boxes cleaned and mounted before April — 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.

Native Colorado plants that attract tree swallows

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

New England aster

Symphyotrichum novae-angliae · Perennial

Late nectar for insects and fall seed for sparrows.

Tall goldenrod

Solidago altissima · Perennial

Insect-rich in fall and seed in winter.

Chokecherry

Prunus virginiana · Shrub

Dark summer fruit and heavy caterpillar load.

Ponderosa pine

Pinus ponderosa · Tree

Seeds and bark insects; pygmy nuthatch and woodpecker habitat.

Gambel oak

Quercus gambelii · Tree

Acorns for jays and woodpeckers across the southern Rockies.

Rabbitbrush

Ericameria nauseosa · Shrub

Late-season bloom supports insects; seed for sparrows.

Douglas fir

Pseudotsuga menziesii · Tree

Seed for crossbills, siskins and chickadees.

Willow (Bebb)

Salix bebbiana · Shrub

Early catkins draw insects for arriving warblers and hummingbirds.

Feeding tree swallows through the Colorado year

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 Colorado's summer: offer water and insect foods; natural food is abundant.

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

Frequently asked

Are tree swallows in Colorado year-round?

No. Tree Swallows are summer breeders in Colorado and leave for the winter.

When do tree swallows nest in Colorado?

Nesting in Colorado typically runs May–June, with 1 per season. Clutches are 4–7 eggs, incubated for 11–20 days.

What native plants attract tree swallows in Colorado?

New England aster, Tall goldenrod, Chokecherry, Ponderosa pine, Gambel oak, Rabbitbrush, Douglas fir, Willow (Bebb) are native plants in Colorado that provide food or cover for tree swallows.

What size birdhouse hole do tree swallows need?

1 1/2 in, with a floor of 5 × 5 in mounted 5–10 ft.

Other backyard birds in Colorado

Black-capped Chickadee Downy Woodpecker Hairy Woodpecker American Goldfinch White-breasted Nuthatch House Wren House Finch Mourning Dove American Robin Dark-eyed Junco Song Sparrow Chipping Sparrow Northern Flicker Red-breasted Nuthatch Brown Creeper Common Grackle Red-winged Blackbird Evening Grosbeak Pine Siskin Indigo Bunting Gray Catbird Northern Mockingbird Brown Thrasher Cedar Waxwing Barn Swallow Yellow-rumped Warbler Eastern Screech-Owl Eastern Kingbird American Tree Sparrow House Sparrow European Starling Steller's Jay Woodhouse's Scrub-Jay Black-billed Magpie Canada Jay Mountain Chickadee Bushtit Juniper Titmouse Pygmy Nuthatch Black-chinned Hummingbird Broad-tailed Hummingbird Lesser Goldfinch Cassin's Finch Spotted Towhee Canyon Towhee Gambel's Quail Western Bluebird Mountain Bluebird Say's Phoebe Ladder-backed Woodpecker Curve-billed Thrasher Bewick's Wren White-crowned Sparrow Fox Sparrow Violet-green Swallow Black-headed Grosbeak Lazuli Bunting Bullock's Oriole Eurasian Collared-Dove

Sources

Timing reflects typical patterns for the region as a whole; local dates vary with elevation and year. Check the linked eBird bar charts for your county.