Just to follow up on my posting about hybrid Rufous/Allen's Hummers and the
research done by Rankin et al. I found that Rankin also coauthored another
more recent article on hummingbird hybridization, here it is:
Banding data show hummingbirds have high rates of hybridization.
Christopher J. Clark, David T. Rankin, and Carl E. Rudeen. Auk: Volume
139, 2022, pp. 1–9 https://doi.org/10.1093/ornithology/ukab067.
ABSTRACT
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.
Tim R
Coos Bay
