IBRC 32-B-11

Idaho Bird Records Committee
Rarities Report Form

Species: Mourning Warbler

Reporter: (include address, phone, e-mail) Steve Butterworth 960 Country Road, Idaho Falls Idaho, 83402, (208) 522-6493, tntbutters@cableone.net

Other Observers: CLiff and Lisa Weisse, Darren Clark, Bill Schiess

Date Report Prepared: May 30

Date Sighting Occurred: May 28th at ~ 9:30 -11:00 AM

Locality of Observation: Camas National Wildlife Management Area

Habitat: Flooded Grass and brushy debris under Cottonwood trees bording Camas Creek

Conditions: Light Overcast

Did you take notes…  Later that day

Did you consult a field guide or other reference work?

during the observation?____________

later the same day? ____X___________

another day? _____________________

not at all? ________________________

What guide(s) or reference(s) did you consult?

Description: Stokes, Field Guide to the Birds of North America, Petersons Field Guide to North America, SIbley's, National Geographic Complete Birds of North America

Behavior: Remained low and prefered to stay over flooded Grass and brush under Cottonwood trees along Camas Creek. Did not go much high than a couple of feet and would dive into gras at times remaining hidden unless flushed. Preferred cover and when in a more open area was extremely mobile to get back into cover.

How and when did you positively identify the bird, and what clinched the identification for you?

Was not the original observer so I was looking for it when I noted the dark face right away with the gray on head also darker than MacGillivray's seen on the same day in the same lighting conditions. Black Breast band was distinct and much larger and wider than those observed in the past and since on a male Macgillvay's. Chip noted was detected and compared to recorded chip notes of a Mourning Warbler. MacGillivay's was also observed and chip notes detected that were flat and not as sharp as the Mourning Warbler. Chip notes noted on MacGillivay's from recordings matches those on MacGillivay's observed.

How did you eliminate similar species, and what were they?

Small 1-2 feathers of eye-arch was minimal and not thick like on MacGillivay's and only visible when light was just right. ALL other MacGillivray's noted that day had a lighter gray head (even Males) with heavy very distinct eye arcs that were very visible under the light conditions. Conneticut and Nashville Warblers were eliminated as there was no eye ring. Conneticut was also eliminated as the observed warbler hopped on logs rather than walked and Nashville was also eliminated due to the Dark Gray throat and Black breast band rather than a yellow.

Experience with this species (and similar species): This was the first Mourning Warbler observed but I have observed many MacGillivay's for many years and was surprised that the Mourning Warbler observed was similar but distinct from a MacGillivay's. This may not be the case for lighter females but for males there appears to be more of a distinction than noted in some of the field guides. Some Guides also pointed this observation out that males of the species are more readily distinguished.

General birding experience: Over ten years of birding in Idaho, numerous trips to Southeast Arizona and Florida.

Were photo(s), video, and/or audio obtained by you? (If yes, please include or attach) No, others (Bill Schiess and Darren Clark) were able to get photographs but no recordings were obtained by any of the observers.