Where to Put a Tree Swallow Nest Box: Height, Spacing & Pairing

Quick answer: Put a Tree Swallow nest box in open habitat, preferably near water, with plenty of flying insects and an unobstructed flight path. Cornell NestWatch currently recommends mounting the box about 5–6 feet high, spacing independent Tree Swallow boxes about 35 feet apart, and facing the entrance south or east. If Tree Swallows and bluebirds compete for boxes, a paired-box setup roughly 15–25 feet apart can help both species coexist.

Tree Swallows readily use nest boxes, but placement is not just about height. Their best breeding habitat combines open flying space, nearby insect-rich habitat and cavity availability. Cornell describes fields, marshes, shorelines, wooded swamps and beaver ponds—often close to water—as typical breeding habitat.

Start With Open Habitat Near Water

Tree Swallows are aerial insect hunters. Cornell’s All About Birds account says they breed in fields, marshes, shorelines, wooded swamps and beaver ponds, with a strong preference for areas near water that produce abundant flying insects.

NestWatch adds a practical backyard cue: Tree Swallows do well in areas with high unmowed grass, preferably near water.

How High Should a Tree Swallow Box Be?

NestWatch currently recommends a narrow placement range of about 5–6 feet above the ground.

That modest height is useful for practical reasons too: a box can remain easy to inspect, clean and maintain while still fitting current species guidance.

OwlRatings’ broader birdhouse height guide explains why mounting height should be chosen by species rather than using one generic backyard rule.

Face the Entrance South or East

NestWatch lists south or east as the preferred entrance directions for Tree Swallow boxes.

Direction should still be combined with common-sense site selection. Keep the approach to the entrance open, avoid branches immediately in front of the hole and prioritize a location that faces usable open habitat rather than forcing a compass direction into a poor site.

For the broader multi-species comparison, see what direction a birdhouse should face.

Use the Correct 1⅜-Inch Entrance

NestWatch currently lists a 1⅜-inch round entrance for Tree Swallows, with about 9 inches of internal depth and an internal floor around 5½ by 5½ inches.

Do not enlarge the entrance just because a larger hole appears easier to enter. The opening is part of the box’s species filter and can affect which competitors gain access.

See OwlRatings’ birdhouse hole-size guide for broader species comparisons.

How Far Apart Should Tree Swallow Boxes Be?

NestWatch recommends about 35 feet between Tree Swallow boxes. That is the species-specific spacing figure to use when you are placing multiple boxes intended for separate Tree Swallow pairs.

Do not confuse that number with the closer spacing used in a paired-box strategy for Tree Swallows and bluebirds. The two setups solve different problems.

For broader spacing recommendations, see OwlRatings’ nest-box spacing guide.

Tree Swallow + Bluebird Paired Boxes: Use About 15–25 Feet

Tree Swallows and bluebirds can compete for the same nest-box sites, but they may tolerate each other at distances where they would not tolerate another pair of their own species.

Cornell’s current NestWatch pages give slightly different paired-box numbers:

• The Tree Swallow species page suggests adding a bluebird box about 20–25 feet away.
• The Eastern Bluebird species page suggests pairing boxes about 15–20 feet apart.
• NestWatch’s general placement guidance describes paired boxes as about 15–25 feet apart.

The simplest way to reconcile those recommendations is to treat 15–25 feet as the working range, with roughly 20 feet as an easy practical target when your site allows it.

Keep the paired set separated from the next pair according to the territorial spacing of the species you are managing. For Eastern Bluebirds, NestWatch recommends about 300 feet between pairs.

OwlRatings’ Eastern Bluebird placement guide covers the bluebird side of the pairing strategy.

Add a Fledgling Ladder Inside the Box

NestWatch recommends a fledgling ladder below the inside of the entrance hole. The goal is to give nestlings secure footing as they climb toward the opening.

Two common approaches are:

• shallow horizontal kerf cuts in the inside front wall, or
• a securely attached piece of hardware cloth below the entrance.

Whatever method you use, make sure it has no loose sharp edges or protruding fasteners.

Predator Protection Matters

NestWatch recommends installing a predator guard on the pole. A freestanding pole with a suitable baffle is generally easier to protect than a box attached to a climbable trunk or fence.

The aim is not to promise a completely predator-proof box. It is to remove the easiest access routes before eggs or nestlings make the cavity a predictable food source.

See OwlRatings’ birdhouse predator-guard guide and tree-vs-pole comparison for the broader setup trade-offs.

Do Tree Swallows Need Nesting Material Added?

Tree Swallows build their own nest, commonly using grass and lining the cup with feathers. You do not need to build a nest for them.

NestWatch notes that Tree Swallows benefit from feathers and suggests that clean chicken feathers can be offered in the area for the adults to collect themselves.

That is different from stuffing the box with miscellaneous nesting material. Avoid string, dryer lint, cloth and other material that can tangle around birds.

For broader guidance, see OwlRatings’ birdhouse nesting-material guide.

Install the Box Before Tree Swallows Return

Cornell recommends putting nest boxes up well before breeding season. Tree Swallows return north early in spring compared with many other swallow species, so an established box should be available before pairs begin settling on territories.

Early installation also gives you time to check the pole, predator guard, entrance, drainage and fledgling ladder before the box becomes active.

Clean the Box After the Brood Is Finished

NestWatch notes that Tree Swallows typically attempt only one brood. Once the young have left and the box is clearly inactive, clean out the old nest.

That makes the cavity available to other species—such as bluebirds—that may still attempt another nest later in the season.

Do not clean an active nest. If you are monitoring the box, use a low-disturbance routine and confirm the nesting stage before maintenance.

See how to monitor a nest box for the general checking routine.

Tree Swallow vs. Violet-green Swallow: Similar Box, Different Placement

Tree Swallows and Violet-green Swallows can use very similar nest-box dimensions, including a 1⅜-inch entrance and 5½-by-5½-inch floor. Placement differs.

So identify the local swallow before assuming that one swallow-box placement recipe applies everywhere.

A Five-Minute Tree Swallow Box Audit

Bottom Line

A good Tree Swallow nest-box site combines open insect-rich habitat with correct spacing and a box the birds can safely enter and leave.

Use about 5–6 feet of mounting height, 35 feet between independent Tree Swallow boxes, a south- or east-facing 1⅜-inch entrance and a fledgling ladder inside. If bluebirds compete for the same site, use the broader NestWatch paired-box range of roughly 15–25 feet instead of treating one species page’s number as universal.

Sources & Further Reading

• Cornell NestWatch — Tree Swallow
• Cornell NestWatch — Nest Box Placement
• Cornell NestWatch — Eastern Bluebird
• Cornell NestWatch — Violet-green Swallow
• Cornell Lab — Tree Swallow Life History

Jonathan Gron

Jonathan Gron is the founder and editor of OwlRatings, where he researches birding, backyard wildlife and practical bird-safety guidance using current primary, government and professional sources.