Abstract North American bluebird enthusiasts intent on minimizing the use of nestboxes by non‐native house sparrows ( Passer domesticus ) use a variety of management techniques, selected with little or no evidence on their efficacy. We investigated two volunteer management interventions that prevent house sparrow reproduction: swapping eggs with replicas (Swaps) and removing eggs and nest material (Removals). In a U.S.‐based citizen science project, Sparrow Swap , volunteer nestbox monitors with house sparrow nests carried out Swaps ( n = 209) more often than Removals ( n = 79). House sparrows nested twice as quickly after Removals (9.8 ± 4.40 days) than Swaps (16.0 ± 6.33 days). Outcomes differed following Removals and Swaps ( χ 2 (3, N = 288) = 46.146, p < .001) with more abandoned nestboxes after Swaps (37%) than Removals (23%) and fewer house sparrow nests after Swaps (24%) than Removals (52%), yet more native species nests after Removals (14%) than Swaps (2%). Swaps and Removals supported different management priorities and practices.
Hartley et al. (2026) studied this question.