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Dryad

Data and Supplementary Material from: Detailed nesting phenology of the first reported case of same-season nest reuse in Anna’s Hummingbirds (Calypte anna)

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Jun 10, 2026 version files 266.11 MB

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Abstract

Natural history observations of rare events can provide invaluable data about the range of variation in a trait or behavior. In birds, these fortuitous observations can help supplement scientific understanding of the timing and location of nesting behavior, events which are often difficult to observe. Reuse of cup nests is thought to rarely occur across species, but incidental reports document nest reuse both within and across breeding seasons. Here, a chance occurrence of a female Anna’s Hummingbird (Calypte anna) initiating a nest on our balcony in California was an opportunity to make detailed observations of nesting phenology with photos and videos. After successful fledging of this first nest, the same female immediately initiated a second nesting attempt in the same nest. To our knowledge, this is the first documented case of same-season nest reuse by the same female in Anna’s Hummingbird, and only the second case confirmed through direct observations in any hummingbird species. The nearness of the nest allowed us to characterize the timing of key events in egg laying, incubation, hatching, and nestling development during both nesting attempts. Our observations add to the rich history of documenting breeding behavior in Anna’s Hummingbirds through incidental natural history observations.