25 October 2021 Banding data show hummingbirds have high rates of hybridization
Christopher J. Clark, David T. Rankin, Carl E. Rudeen
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We estimate hybridization rates among hummingbirds using nearly a million banding records from the United States and Canada. Annually from 2006 to 2019, an average of 44,600 individual hummingbirds and 14 hybrids were banded. Nearly all reports of hybrids come from localities west of the Mississippi, where multiple species breed in sympatry, whereas only Ruby-throated Hummingbird (Archilochus colubris) breeds east of the Mississippi. Adult male hybrids comprise 62% of all hybrids banded, a significantly greater fraction than “regular” adult males, which are 29% of all birds banded (excluding Ruby-throated Hummingbird). We infer that this excess of adult male hybrids is caused by ascertainment bias: banders more often misidentify female hybrids as parental species because females mostly lack species-specific showy sexual ornaments of male hummingbirds, making them harder to identify, rather than Haldane's rule of reduced survivorship of the heterogametic sex. Also influencing the apparent hybridization rate are banders, a few of whom seek out or avoid hybrids. After considering these biases, the data suggest that, in areas of the United States and Canada with >1 species, approximately 1 hummingbird in a thousand (0.1%) is an F1 hybrid.


  • Nearly a million hummingbirds have been banded in the United States and Canada since 1960.

  • West of the Mississippi, roughly, 0.1% of wild hummingbirds are F1 hybrids.

  • This estimate excludes birds from hybrid zones.

  • More adult male hybrids are reported than adult female hybrids.

  • This is due to ascertainment bias: banders misidentify hybrid females more often than hybrid males.

Copyright © American Ornithological Society 2021. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.
Christopher J. Clark, David T. Rankin, and Carl E. Rudeen "Banding data show hummingbirds have high rates of hybridization," Ornithology 139(1), 1-9, (25 October 2021). https://doi.org/10.1093/ornithology/ukab067
Received: 27 March 2021; Accepted: 28 September 2021; Published: 25 October 2021
anillado de aves
bird banding
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