ABSTRACT
We compared reproductive success of Tree Swallow (Tachycineta bicolor) and House Wren (Troglodytes aedon) nests in wooden nestboxes to insulated metal nestboxes to determine if a new insulated metal nestbox design is a safe alternative to wooden nestboxes. We also examined the preference of four species of cavity-nesting birds to nest in wooden versus metal nestboxes. No significant differences were found among clutch size, hatching success, and the number of fledglings produced in Tree Swallow and House Wren nests between the two types of nestboxes. Therefore, insulated metal nestboxes appear to be a safe alternative to wooden nestboxes. Metal nestboxes were preferred by Tree Swallows to wooden nestboxes (χ2 = 6.5, n = 25, p = 0.01). However, wooden nestboxes were preferred to metal nestboxes as a first choice for nesting 77.1% of the time for all four species. House Wrens, Eastern Bluebirds (Sialia sialis), and House Sparrows (Passer domesticus) all preferred wooden to metal nestboxes (Fisher's Exact Tests, all p < 0.001). Thus, insulated metal boxes are safe, but may not attract desirable species, such as Eastern Bluebirds, when compared to traditional wooden Peterson-style boxes.
