🪺 Bird Nest Box Dimensions Guide

Cornell Lab of Ornithology nest box builder. Exact hole diameters, interior floor dimensions, and predator exclusion clearance for native cavity nesters.

ENTRANCE HOLE
1-1/2" (38 mm)
Blocks Starlings
FLOOR DIMENSION
5" x 5"
Interior Space
MOUNT HEIGHT
5 to 8 ft
With Stovepipe Baffle
📐 Architectural Construction Specs:
Ornithological Rule #1: NEVER add a perch! Cavity-nesting songbirds have strong zygodactyl/anisodactyl feet and cling easily to natural rough wood. Exterior perches only give invasive House Sparrows and predatory snakes/jays a foothold to raid the nest.