I’m sure this is among the work you’re talking about, but just in case/for
others who missed it:
https://academic.oup.com/auk/article/136/4/ukz049/5565029
is a brilliant and intriguing read.
-Stephen
On Fri, Sep 3, 2021 at 6:30 PM larspernorgren <larspernorgren@xxxxxxxxx>
wrote:
I'm pretty sure the extent of green on the back is a bit of a red herring.
Over the decades multiple birders have told me about RUHU with extensive
green backs they saw 100s of miles from the traditional Allen's range.
Broad-tsiled Hummingbird is also a Selaspjorus, with no rufous anywhere. I
think the green is sometimes an ancestral trait rather than Allen's DNA
residual from recent crossing. Tail feathers are important in many of these
hummingbird quandaries, and there's display flight. The cumulative wisdom is
that hybrid AllenxRUHU is the rule throughout its Oregon "range". The
whole thing is a hybrid zone . I'm pretty sure Tim Ridenkirk has observed
birds in downtown Coos Bay that displayed significant Allen's traits.
Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------
From: Tanner Martin <simonthetanner@xxxxxxxxx>
Date: 9/3/21 5:14 PM (GMT-08:00)
To: OBOL Oregon Birders Online <obol@xxxxxxxxxxxxx>
Subject: [obol] Rufous vs. Allen's Hummingbird Question
Hey all,
So I’ve been reading up on the Allen's x Rufous hybridization zone, and it
has left me with some questions about Allen's / Rufous type hummingbirds
that I’d love some help with. I’m located in Josephine County, so I’m far
more interested in this discussion as it pertains to identifying inland
hummingbirds rather than coastal hummingbirds.
The article I’ve seen, by Myers, Rankin, Burns and Clark, is primarily
focused on the coast. Only 9 total specimens were taken inland, from
Josephine and Siskiyou counties. Neither inland county produced a pure
Allen’s Hummingbird, and both showed a majority of hybrids with a minority
of pure Rufous. (“Pure” being a relative term, of course)
I don’t know how much should be concluded from the small number of inland
samples, given the size and diversity of the region; but the data suggests
that (1) most Rufous-type hummingbirds found here are hybrids, (2) most of
the rest are Rufous, and (3) a pure Allen’s is unlikely despite the strong
genetic influence. I wish the study had mentioned specifically where these
specimens were taken, as geography certainly impacts how we should
interpret the data. My own experience in Josephine County is that in the
southern and western parts of the county you encounter a fairly high
percentage of fully green-backed, more Allen’s-like hummingbirds, while to
the north and east you encounter almost exclusively typical orange-backed
Rufous. There’s obviously a lot of Allen’s Hummingbird DNA floating around,
but it seems to be more prevalent on one side of the county than the other.
So here are my questions: What do I need, as a birder in the inland part
of the hybridization zone, in order to confidently identify a pure Rufous
or Allen's hummingbird? Even though Rufous is the default species on this
side of the state line, what does it take to conclusively and definitively
rule out a hybrid? And if one did eventually find a good candidate for
Allen’s this far inland, what is needed to adequately document it?
Thanks in advance for any insight,
Tanner Martin
