One note to add to Jon Isacoff's excellent post:
The Idaho Rare Bird Committee has one to three accepted Glossy Ibis reports each year since 2005.
These have been in the April -June period except for a 3 September bird in 2008.
All reports have been from SE Idaho.

There have been several reports of hybrid birds from this same area, one as recently as 20 July 2012 http://www.flickr.com/photos/50655108 at N05/7613164184/

Keith E. Carlson
Lewiston
----- Original Message -----
From: Jonathan B. Isacoff
To: inland-nw-birders at uidaho.edu
Cc: tweeters at u.washington.edu
Sent: Saturday, August 11, 2012 9:44 AM
Subject: [inland-NW-birders] Mann Lake Ibis


I am not a "dark ibis expert" but I do see both species, including juveniles, nearly annually at various locations around the US. From the discussions threads on INWB, most of the key facts are already there:


* 1st year ibis's look very similar, hence are tough to ID
* as many have already noted, dark iris on a juvenile WF Ibis is typical until around February
* juveniles of both species can show a mottled bicolored bill. At this stage, the two species are virtually indistinguishable


With 99% confidence the Mann Lake bird is a typical juvenile White-faced:


* First and foremost: when analyzing 2 extremely similar species, good birders assume the ID to be the "expected species" unless there is something strikingly atypical to suggest otherwise
* There is nothing atypical on this ibis to suggest anything other than White-faced. More specifically:
(1) The dark iris is typical of White-faced at this stage;
(2) Once the bi-coloration of the bill has matured into a solid color, White-faced, nearly always show a gray or blueish-gray as the Mann Lake bird does. Glossy show a pinkish, brownish, or pinkish-brown bill. Guides don't mention this because a "true juvenile" has a mottled bi-colored bill, but once the more mature solid color is established, bill color is a diagnostic key of dark ibises. Glossy Ibis's never have a gray of blueish-gray bill.
(3) There was some mention of white loral lines on young Glossies, which can be helpful if all other factors are unclear. Perhaps some other observer can detect these but I see no hint of white loral lines on the Mann Lake bird.


A note on why White-faced is clearly the "expected species;"


* White-faced Ibis is a regular established breeder at Malheur in Eastern OR, Freezeout Lake in Western MT, and a host of locations in Southwestern ID. I'd have to double check but I believe there is a recent historical breeding record from Columbia NWR in WA. It is expected that juvenile birds will drift from these relatively nearby breeding sights to places like Mann Lake. Indeed, it is surprising that juvenile birds have not been seen there before.
* The closest breeding site for Glossy Ibis is Southeastern TX.


I'd be happy to learn a new fact about ibis's that help with ID, but the Mann Lake bird looks to be a perfectly typical juvenile White-faced.


Good birding,
Jon Isacoff, Spokane


Jonathan B. Isacoff
Chair, Environmental Studies
Associate Professor, Political Science
Gonzaga University, Box 52
Spokane, WA 99258-0052
isacoff at gonzaga.edu








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