Date: 7/25/25 7:51 pm From: Erik Thomas (via carolinabirds Mailing List) <carolinabirds...> Subject: Re: Huge Kettle of Common Ravens (Not in Carolinas) and strange appearing Downy WP
You could probably add the Purple Finch/Cassin's Finch complex to that
list. Same with the White-breasted Nuthatch. Dark-eyed Juncos probably
represent a similar scenario, but with more complexity in the Rockies.
The Pleistocene situation is interesting but complex because, as we
now know, there were dozens of glacial periods (not just four, as was the
standard explanation when I was growing up, which might date me...). All
of that produced a lot of boomeranging by species between glacial refugia
and interglacial northern ranges, the latter offering opportunities for
eastern, Rocky Mtn., and Pacific coast populations to intermingle. It
would be fascinating if we could follow how all the populations navigated
the climate teeter-totter throughout the Pleistocene and how genetic
differences developed and accumulated.
Some of you may be familiar with a paper that appeared in one of the
ornithology journals during the 1960s that tried to explain the
Black-throated Green Warbler complex in terms of Pleistocene movements. It
theorized that the original population lived in the east, and that
successive movements westward during interglacial periods produced the
Black-throated Gray, Hermit, and Townsend's Warblers (it also explained the
Golden-cheeked Warbler as a refugial remnant). We now know that this
explanation was incorrect--for one thing, Townsend's and Hermit Warblers
are sisters to each other, and for another, all of these species appear to
be older than previously thought, and in addition, the Prairie Warbler may
be closer to the Black-throated Green, Golden-cheeked, Townsend's, and
Hermit Warblers than the Black-throated Gray is. It also used the old
scheme of there being just four major glacial periods, positing that the
Black-throated Gray emerged in the interglacial between Nebraskan and
Kansan, the Hermit in the Kansan/Illinoian interglacial, and the Townsends
in the Illinoian/Wisconsinan interglacial. Geologists no longer recognize
the Nebraskan and Kansan as valid glacial periods. Nevertheless, it was a
nice try back in the day, given what was known during the 1960s. Of
course, it does point out the hazards of making projections about how
present-day species relate to glacial periods.
Even so, it stands to reason that Pleistocene glacial and interglacial
periods had important effects on speciation and subspeciation. It would
still be intriguing if we *could* know just what the impact of glacial
periods was on the divergence of various bird populations.
Erik Thomas
Raleigh, NC
On Fri, Jul 25, 2025 at 10:19 PM Wayne Hoffman <carolinabirds...>
wrote:
> Hi all -
>
> This Downy Woodpecker discussion brings up some interesting bird
> biogeography. Sibley pictures "Pacific," "Interior West," and "Eastern"
> groups of Downies. Pyle breaks up the 7 subspecies he recognizes into the
> same groups - 3 "Coastal Pacific," 2 "Interior Western," and 2 "Eastern"
> subspecies. Note that the "Eastern" group is really Eastern + Boreal, and
> extends into the interior of Alaska.
>
>
> There are a bunch of forest bird species and species groups that divide
> similarly into Pacific, Interior Western, and Eastern (+ Boreal). Some
> have been split into 3 species, for example sapsuckers, "Solitary" vireos,
> and bluebirds. Others including Downies have not differentiated enough to
> be recognized as species, but their geographic variation follows the same
> pattern. Examples include Hairy Woodpecker (also has Mexican subspecies), Warbling
> Vireo, Canada Jay, Common Raven, Horned Lark, Black-capped Chickadee,
> White-breasted Nuthatch, Marsh Wren, Golden-crowned Kinglet, Orange-crowned
> Warbler, Wilson's Warbler, and White-crowned Sparrow.
>
> The Warbling Vireos have been proposed for splitting into 2 species,
> eastern and western, the latter with 2 subspecies. Ditto for Marsh Wrens,
> but with more subspecies in each group. Nashville Warblers have also been
> proposed for splitting into 2 species, eastern (Nashville) and Western
> (Calaveras), and Virginia's Warbler is a very close relative with an
> interior southwestern distribution.
>
> Why do all these species/groups have similar patterns of geographic
> variation? They probably all were divided into three separated populations
> during the Pleistocene glaciations, with the Eastern ones inhabiting the
> southeastern US, the Pacific ones along the Pacific coast south of
> Washington, and the interior western ones in the southern Rockies, probably
> extending further into Mexico than the do now. During the glacial maxima,
> the Pacific and interior ranges were more separated than now, because the
> Cascades and Sierra Nevada, and likely other southwestern ranges were much
> more heavily glaciated.
>
> Wayne Hoffman
> Wilmington
>
>
>
> ------------------------------
> *From: *"Susan Campbell" <susan...>
> *Cc: *"carolinabirds" <carolinabirds...>
> *Sent: *Friday, July 25, 2025 8:13:40 PM
> *Subject: *Re: Huge Kettle of Common Ravens (Not in Carolinas) and
> strange appearing Downy WP
>
> Ok-- that woodpecker does look odd. Guess it is a Downy variant.....
>
> Susan
>
> Get Outlook for iOS <https://aka.ms/o0ukef> > ------------------------------
> *From:* <carolinabirds-request...> <carolinabirds-request...>
> on behalf of David Campbell <carolinabirds...>
> *Sent:* Friday, July 25, 2025 8:04:28 PM
> *To:* Chris Snook <snookcf62...>
> *Cc:* <carolinabirds...> <carolinabirds...>
> *Subject:* Re: Huge Kettle of Common Ravens (Not in Carolinas) and
> strange appearing Downy WP
>
> Both Downy and Hairy woodpeckers show appreciable geographic variation in
> the amount of black. Sibley and National Geographic guides illustrate some
> of the range, without full details of subspecies. The Ladder-backed
> consistently lives up to its name, with a ladder pattern on the back, so
> the photographed bird would be a Rocky Mountain morph Downy.
>
> On Friday, July 25, 2025, Chris Snook <carolinabirds...> wrote:
>
> I think that a group of Ravens is called an unkindness of ravens.
>
> Chris Snook,
> Charleston, SC.
>
> On 7/25/2025 18:21, KEN LIPSHY (via carolinabirds Mailing List) wrote:
>
> I apologize for this out of state Raven Behavior Question but this
> afternoon At the Audubon center in Santa Fe i counted well over 100 Common
> ravens in a kettle overhead.. … is that typical? I looked online to see but
> there is no mention of Raven Kettles that large.
> Also there is a Downy WP photo on that page that looks quite different to
> me as well- welcome any input (I used to contact Ned Brinkley for out of
> state questions but sadly he is not with us)
>
> https://ebird.org/checklist/S262668320 >
>
>
>
> --
> Dr. David Campbell
> Professor, Geology
> Department of Natural Sciences
> 110 S Main St, #7270
> Gardner-Webb University
> Boiling Springs NC 28017
>
>
>
