Rare Bird Report #39-B-09
Idaho Bird Records Committee
Rarities Report Form
Species: Glossy Ibis
Reporter:
Cliff Weisse
4125 Beaver Springs Rd.
Island Park, ID 83429
cliffandlisa@octobersetters.com
Other Observers: Jay Carlisle, jaycarlisle@boisestate.edu / Heidi Ware, heidithebirdnerd@yahoo.com
Date of Observation: 2 June 2009
Date Report Prepared: 6 June 2009
Locality of Observation: Market Lake WMA, Jefferson County
Habitat: Flooded fields close (within 2 miles) to breeding colony located in the marshes at Market Lake.
Conditions: During first observation at about 7:00 AM it was raining with no wind. The bird was in a flock of WFIB foraging in a private farm field adjacent to the frontage road west of I-15 and about 2 miles from the nesting colony at the north end of Market Lake WMA. Distance to bird was approximately 75 yards. I viewed the bird through a Swarovski 80MM HD scope at up to 60x for about five minutes. Lighting conditions were poor and my ability to determine iris and bill color was compromised as a result. During the second observation at about 10:00 AM it was raining lightly but much brighter. This time the bird was in a field between I-15 and the main Market Lake WMA road along the west side of the marshes. Distance was again about 75 yards and the bird was viewed through the same scope for 5-10 minutes.
Did you take notes… No
Did you consult a field guide or other reference work? No
Description:
First observation: Obvious adult Plegadis ibis with chestnut and green plumage. Legs were gray with reddish knees. Bill color did not appear to be different from surrounding White-faced Ibis but I was not sure I could see well enough to say for sure that the bill was the same color as on the WFIB. The eye appeared dark but I was not able to see red in the eyes of the surrounding WFIB so I don't think eye color could be determined. Facial skin was dark slate gray with pale blue lines adjacent to the feathering surrounding the bill. These pale lines were confinded to the facial skin and did not bleed into the feathers at all. The pales lines exteded up to the eye but did not encircle the eye. There was no hint of any red, purple, or lavendar coloration to the facial skin or the pale lines on the edges of the facial skin.
Second observation During the second observation I was able to confirm the same facial pattern described above, again with no hint of red/purple/lavendar that would suggest hybridization with WFIB. The legs were not visible. I spent most of the observation time looking at the eye of this bird and the surrounding WFIB. I was still not able to say with certainty that I saw red in the eyes of the WFIB but I was able to see, very clearly, that the pupil was dark/black and the surrounding iris was significantly paler. The GLIB had completely dark eyes at all times. It was preening so it was turning its head constantly and giving me different angles, the same angles that revealed the bicolor eye of the WFIB perched close by.
Behavior: During the first observation the bird was foraging in a large flock of WFIB (maybe 1500) in a stubble/dirt field that was being flooded. It foraged by walking along and probing in the dirt. During the second observation there was a flock of several hundred WFIB foraging in a flooded weedy field. There was a group of about 100 individuals perched on a dike near the foraging flock. This smaller flock was preening and birds would regularly fly from the foraging flock to the preening flock and vice versa. I sat and watched this preening flock for about 20 minutes before the GLIB arrived. It stood pretty much in the same location and preened during the entire observation.
How and when did you positively identify the bird, and what clinched the identification for you? Upon seeing the pattern on the face I was sure of the identification. Other supporting field marks were obtained to further support the ID but the facial pattern is diagnostic.
How did you eliminate similar species, and what were they? WFIB and WFIB x GLIB are the only possible species of confusion. White-faced has at least some white or pinkish in the feathers surrounding the eye and does not have pale blue lines on the facial skin surrounding the face. Hybrids between White-faced and Glossy can show the same face pattern but they always have red or purplish color on the facial skin and the pale lines on the face are typically lavendar in color. The eye is variable but is not completely dark, always showing at least a hint of red. Given the extended views I had of the eye I feel I would have been able to see the difference between pupil and iris color if this was a hybrid.
Experience with this species: I've studied WFIB fairly extensively for at least the past five years. I've seen Glossy Ibis and Glossy x White-faced hybrids annually since 2006. I feel I am very familiar with separation of WFIB, GLIB, and hybrids thereof.
General experience birding: 16 years
Were photo(s), video, and/or audio obtained by you? No