Possible Glossy Ibis (Plegadis falcinellus)
Lake Merced, San Francisco, SF, California
24 September 2005
Joseph Morlan

Today, Robbie Fischer and I birded the southern part of Lake Merced as part of the San Francisco Rare Bird Roundup organized by Hugh Cotter and Alan Hopkins. Mid-morning Robbie called me on the radio to alert me that an ibis was flying over the southern impoundment. I was birding the nearby Vista Grande Canal and so I headed for Lake Merced Drive where I saw the ibis flying low over Lake Merced north of the concrete bridge. I watched as it turned and headed back south. I joined Robbie at the bridge and we watched the ibis circle around for several minutes. It looked like it was going to land, but kept circling. Robbie alerted David Armstrong by cell phone. Soon the bird landed on the small area of open mud just southwest of the bridge. I got my scope while Robbie called the birdbox and alerted others. I took several photographs, two of which are reproduced here. David Armstrong and Adam Winer came down and saw the bird through my scope. I had assumed that the bird was a White-faced Ibis. This is a very rare bird for San Francisco with only a handful of previous sightings. However, I did consider the remote possibility of Glossy Ibis. My recollection was that immatures of these two species were virutally impossible to separate, but I thought I noted a reddish cast to the eye which I felt was indicative of White-faced.

Description

I did not take notes at the time, but concentrated on photography instead. Photos were digiscoped, hand-held, with an Olympus D-550z / Nikon FieldScope 3 / 30XWA.

However from memory and reference to photos I can say this was an obvious dark ibis in the genus Plegadis with a long decurved bill and long dark legs. They body was dark sooty gray. The head and neck was dark sooty gray with obvious whitish steaks on the crown and nape. The wing coverts had a dull greenish cast, but looked black under most lighting conditions. I looked for any color in the facial skin and saw none. There was also no red coloration on the legs or other soft parts. When the sun hit the face, the eyes seemed to have a reddish cast.

Discussion

I posted a message on the SFBirds email list with a link to one of the photos I took. Soon I received a private email from Alvaro Jaramillo who noted that the pale stripe extending from the top of the eye to the bill was suggestive of Glossy Ibis. He further noted that the honey-colored eye may be an artifact of reflected light. I have since gone over some correspondence from Bruce Peterjohn who has studied these birds for many years. He also suggested that the eye stripe is the best indicator for Glossy Ibis vs. White-faced Ibis in non-breeding adults. At this stage I am cautious, but will continue to research the issue.

Three full sized images (cropped, but otherwise unedited) are available here.

Comments and/or opinions on the identification of this bird are welcome.