When providing nest boxes for Tree Swallows, it is important to ensure the box is the proper size to meet the needs of this species. Tree Swallows are small, cavity-nesting birds that readily accept man-made nest boxes as substitutes for natural cavities. Providing properly sized nest boxes can help attract these insects eaters to your property.
Entrance Hole Size
The entrance hole is one of the most important dimensions to get right when putting up a nest box for Tree Swallows. The hole should be 1.5 inches in diameter. This size allows adult swallows to easily enter and leave the box, while preventing access from larger species that may compete for the nest site or prey on eggs and nestlings.
If the entrance hole is too large, other birds like starlings may take over the nest box. An entrance hole smaller than 1.5 inches may discourage the swallows from using the site.
Interior Dimensions
In addition to the entrance hole, the interior dimensions of the next box need to accommodate the nesting behaviors of Tree Swallows:
- Depth – At least 6 inches deep from the bottom of the entrance hole
- Floor dimensions – At least 4 x 4 inches
- Height – Optimally 8-12 inches tall
This interior space provides room for the swallow’s nest cup made up of grasses and feathers, allows proper air circulation around the nest, and gives just enough room for the incubating and nesting adults. Too small of a space may deter use, while too large leaves room for other competing species.
Placement Tips
Proper placement of the nest box is also key for attracting Tree Swallows:
- Mount boxes on posts, trees or under eaves 5-15 feet above ground.
- Face the entrance hole away from prevailing winds and rain.
- Place boxes within sight of water as swallows forage for aerial insects over fields, lakes and streams.
- Space boxes 15-100 feet apart near optimal habitat.
Construction Materials
Nest boxes for Tree Swallows should be constructed of weather-resistant untreated wood at least 3/4 inches thick. Avoid boxes made with plastic or metal which may overheat in the sun. The entrance hole can be rough-cut if wood is thick enough. Otherwise, a hole saw or drill bit will cut a clean entrance hole.
The top or side roof of the box should be removable or on a hinge to allow easy annual cleaning and monitoring. Applying a water sealant stain or paint helps protect the exterior of the box.
With the proper dimensions and placement in optimal habitat, a well-constructed nest box will provide Tree Swallows with secure nesting site. In turn, these voracious insect eaters will help control pest around your property while their aerial displays bring beauty and interest to observe.
Nest Box Plans
Here are some sample plans for building a nest box suitable for Tree Swallows:
| Measurement | Dimension |
|---|---|
| External Width | 5.5 – 6 inches |
| External Height | 8 – 12 inches |
| External Depth | 4 – 6 inches |
| Entrance Hole Diameter | 1.5 inches |
| Height of Hole Above Floor | 4 – 6 inches |
| Floor Dimensions | At least 4 x 4 inches |
The plans allow for some flexibility but keeping the entrance hole at the specified 1.5 inches and providing adequate internal floor space are key.
Monitoring and Maintenance
Here are some tips for monitoring and maintaining nest boxes for Tree Swallows:
- Install boxes before breeding season starts.
- Regularly check for occupation and activity during spring and summer.
- Do not disturb nests once eggs are laid.
- Monitor from a distance using binoculars once nesting begins.
- Banding nestlings requires permits and training.
- Clean out old nesting material after young have fledged.
- Clean and disinfect interior annually to prevent parasites.
- Make any repairs and apply fresh protective stain/paint before next season.
Properly monitoring and maintaining nest boxes will allow for their safe reuse for many seasons. Keeping records on activity can provide useful data on breeding success and populations over time.
Conclusion
By providing nest boxes of the proper dimensions and constructed of appropriate natural materials, you can successfully attract Tree Swallows to your property. Optimal box size includes an entrance hole 1.5 inches across and interior dimensions at least 6 inches deep, 4 inches square floor space, and 8-12 inches high. Proper placement in open habitat near water sources and proper annual maintenance will lead to great enjoyment of observing these aerial insectivores as they nest.
