Subject: Re: [LABIRD-L] Identification and Status of White-faced and Glossy ibises in southeastern LA
Date: Sun, 22 Oct 2017 11:39:04 -0500
From: Steven W. Cardiff <scardif@GMAIL.COM>
Reply-To: Steven W. Cardiff <scardif@GMAIL.COM>
To: LABIRD-L@LISTSERV.LSU.EDU

Labirders-
     Van and David nail the problem pretty well.  As for hybrids, an
enlightening photo gallery can be found at:

http://www.pbase.com/joe_grzybowski/ibis_heads

Note that most of the birds in the photos are breeding adults at a breeding
colony in Oklahoma.  In an area such as SW LA where White-faced vastly
outnumbers Glossy, "Glossy-like" hybrids stand out from the White-faced
"matrix" and could easily be mis-identified as pure Glossy.  More
White-faced like hybrids are much more difficult to pick out among the many
pure White-faced.

Research into the genetics of *Plegadis* is in progress at the University
of OK and right here at LSUMNS.  Here's a quote from Joe Grzybowski:

"We have been working out the genetics of Glossy and White-faced ibises and
hybrids.  By phenotype, < 6% of dark ibises in Oklahoma are Glossy or
hybrid phenotypes.
However,  Glossy Ibis genes show up in 26% of the birds, and some (almost)
Glossy phenotypes show White-faced female parentage (mt-DNA).  They are
genetically free mixing.  Can't call genetics on phenotype.  My colleague
describes it as a situation where two species are merging.

We went down to coastal Louisiana to try to get some pure Glossies, and
they are hybridizing there as they are in Oklahoma.  About half the
non-White-faced phenotypes are Glossy or almost Glossy, and about half are
hybrid phenotypes.  Genetics is the same as in Oklahoma."

So, obviously, there can be at least limited hybridization between pure
individuals and then there is a lot of subsequent backcrossing going on to
the point where apparently "pure" individuals can have mixed DNA.

If things are this complex and confusing in the case of breeding adults,
just imagine the difficulty of diagnosing hybrids in immature or
non-breeding adult plumages....

Steve Cardiff

On Sat, Oct 21, 2017 at 5:56 PM, David Muth <MuthD@nwf.org> wrote:

> Labird:
>
> I do want to add some background to this discussion. In southeast
> Louisiana--essentially the deltaic plain east of the Atchafalya Basin, both
> Glossy and White-faced ibis are common. The delta is historically the
> westernmost place where this is true for Glossy, and easternnmost place
> where this true for White-faced. This has been the zone of overlap between
> these two species, and mixed breeding colonies have been known for decades.
> Given the difficulty of field seperation I don't know which is more common,
> but I know that if I get a chance to study a flock I will usually find
> both, and I don't have any expectation of finding that one rather than the
> other will predominate in a given flock (except that White-faced is much
> easier to pick out because white and reddish are easier to see on a dark
> bird than brown and blue).
>
> It used to be that east of the delta White-faced was very rare, and west
> of the delta Glossy was very rare. That is all changing along the coast
> east and west, and both species are making inroads into the continental
> interior. Not surprisingly as well, this pioneering expansion, along with
> digital photography, is leading to the detection of more and more apparent
> hybrids. I don't know if originally the overlapping populations in the
> delta were hybridizing, or had established a stable hybrid zone, but I'd
> guess that now all bets are off, and we should all get used to being asked
> to justify our field identifications.
>
> Bring your cameras, take pictures.
>
> David Muth
> New Orleans
>
> -----Original Message-----
> From: Bulletin Board for Dissemination of Information on Louisiana Birds
> [mailto:LABIRD-L@LISTSERV.LSU.EDU] On Behalf Of Steven W. Cardiff
> Sent: Saturday, October 21, 2017 2:03 PM
> To: LABIRD-L@LISTSERV.LSU.EDU
> Subject: Re: [LABIRD-L] Identification and Status of White-faced and
> Glossy ibises in southeastern LA
>
> Labirders-
>      The only thing I would add is that adults in non-breeding plumage
> retain the "reddish/chestnut" upper wing coverts (shoulder).  This is how
> they can be distinguished from immatures.  So, if you are panning through a
> flock during fall-winter, individuals with the chestnut upper wing patch
> will be adults and should have their definitive iris and facial skin colors.
>
> Steve Cardiff
>
> On Sat, Oct 21, 2017 at 11:52 AM, James V Remsen <najames@lsu.edu> wrote:
>
> > LABIRD:  Part 2:
> >
> > Here are the ID problems, as I understand them so far. Steve, Donna,
> > and others please chime in to repair any damage below:
> >
> > ==========
> >
> > JUVS: these are the brownish necked individuals with few if any
> > streaks, often with pale blotches on the bill.  These are NOT
> > identifiable to species as far as anyone knows and should always be
> > reported as Plegadis sp. in SE LA (including Florida and River
> > parishes). All of them have gray facial skins and dark eyes.
> >
> > ==========
> >
> >  IMMS: In first basic plumage, the neck becomes streaked.  The facial
> > skin is gray in both species.  The iris in White-faced at some point
> > becomes red.  So, if you do see a streak-necked bird with a red eye,
> > then it is WFIB, but a dark-eyed bird cannot be safely identified.  A
> > real problem is that as White-faced matures, it can pass through a
> > stage that looks very Glossy-like in still having dark eye and facial
> > skin but having traces of white around face that can make it look like
> > a Glossy.  For example, the following photos were found by Tony
> > Leukering from CA and NV, where GLIB would be extremely unusual, so
> these are presumably WFIB:
> >
> >  California:  https://macaulaylibrary.org/asset/70670231#_ga=2.29961980.
> > 25890241.1507509707-334541348.1399337695
> >  California:  https://macaulaylibrary.org/asset/68874791#_ga=2.
> > 265350860.25890241.1507509707-334541348.1399337695
> >  California:  https://macaulaylibrary.org/asset/34774341#_ga=2.59837166.
> > 25890241.1507509707-334541348.1399337695
> >  Nevada:  https://macaulaylibrary.org/asset/69398871#_ga=2.
> > 265350860.25890241.1507509707-334541348.1399337695
> >
> >
> > An open question is how early WFIB begin to acquire a red iris.  We
> > can all contribute to this by uploading photos to eBird.
> >
> > ==========
> >
> >
> > ADULTS in basic (non-breeding) plumage, i.e. streaked neck, lack of
> > breeding colors around face (but wing coverts still glossy green etc:
> > the most reliable way to tell them apart is by iris color: red in
> > WFIB, brown in GLIB.  The facial skin should also be pinkish in WFIB,
> gray in GLIB.
> >
> >  =============
> >
> > Summary:  FIRST, put your bird into an age category and then ….
> >
> >
> > 1.    JUVS: cannot be identified to species and should always be listed
> as
> > Plegadis sp. In SE LA.
> > 2.    IMMS: IF the iris is red, then it´s WFIB; otherwise, should always
> > be listed as Plegadis sp. In SE LA.
> > 3.    ADS (non-breeding): If you can see iris color or facial skin, then
> > you can ID them; otherwise, should always be listed as Plegadis sp. In
> > SE LA.
> >
> >  I am skipping the topics of first alternate plumage and hybrids
> > (which are not infrequent), but beware of birds with mixed or
> > intermediate characters.
> >
> > I am going to hit the “reset button’ for SELA Pleads, so all you
> > eBirders should brace yourselves for a barrage of messages.
> >
> > ===================
> >
> > Dr. J. V. Remsen
> > Prof. of Natural Science and Curator of Birds Museum of Natural
> > Science/Dept. Biological Sciences LSU, Baton Rouge, LA 70803
> > najames<at>LSU.edu
> >
> > > On Oct 15, 2017, at 2:17 PM, James V Remsen <najames@lsu.edu> wrote:
> > >
> > > LABIRD:  It is clear from eBird data that observers are
> > > over-reporting
> > Glossy Ibis in southeastern LA based on (1) assumption that most or
> > all Plegadis there are Glossy, and (2) treating any Plegadis as Glossy
> > unless it has obvious white facial markings or red iris.  I have made
> > these mistakes myself.  Both assumptions are wrong.
> > >
> > > To force us all to pay closer attention to their status and
> > distribution, I have zeroed the eBird filters for both species for all
> > of southeastern LA as far west as Terrebonne and around L.
> > Pontchartrain despite the facts that both species are expected there.
> > Briefly, the only way to ID non-breeding plumage Plegadis is by iris
> > color (red in WHFIB, dark in GLIB), and many WFIB to not attain their
> > red eyes until late in their first year, so dark iris is not sufficient
> to call a bird a Glossy.
> > More later in a subsequent message on what I understand concerning their
> ID.
> > >
> > > So, henceforth, you will have to defend your species IDs on these
> > > two in
> > the above regions.  Otherwise, just enter as Glossy/White-faced.
> > >
> > >
> > >
> > >
> > > ===================
> > >
> > > Dr. J. V. Remsen
> > > Prof. of Natural Science and Curator of Birds Museum of Natural
> > > Science/Dept. Biological Sciences LSU, Baton Rouge, LA 70803
> > > najames<at>LSU.edu
> > >
> >
> >
>
>