Documentation of Black-throated Blue Warbler

Observer Information

Reporter:  Joe Mammoser  312 Dunne Drive,   Fort Collins, CO  80525
Other Observers: 

Species, Date, Time and Location Information

Species:  Black-throated Blue Warbler
First Date/Time:  11/2/1993 10:45:00 AM
Last Date/Time:  11/2/1993 11:10:00 AM
Duration (total time in view):  25 minutes
County:  Larimer
Specific Location:  CSU Environmental Learning Center
Number:  1
Age:  Adult
Sex:  Female
Plumage:  Breeding


Russian Olive thicket

Viewing Conditions

Optics:  Bausch and Lomb 8 X 36 Custom binoculars
Distance:  Approximately 20 feet
Light:  Bright with high clouds

Description of the Bird

The bird first was noticed when it made a deep chip call similar to the call of a Dark-eyed Junco. I looked for the supposed Junco and found a small warbler. Brownish-olive on the back and crown. Darker brownish-black on the wings and tail. There was a distinct small white patch at the base of the primaries. The underparts were a buffy tan color transitioning to a lighter whitish tan in the vent area. There was a noticeable whitish buff supercilium over the eye. The throat was a lighter buff than the rest of the underparts. The bill was thin, pointed and black like typical warbler bills. It foraged throughout the Russian Olive thicket from 2 feet to 8 feet off the ground. 

Similar Species Discussion

The thin pointed bill rules out all sparrows, buntings and tanagers. The small size rules out all thrushes and thrashers. The coloration rules out all nuthatches and chickadees. The somewhat longer pointed bill and coloration would rule out gnatcatchers. The frantic foraging style, the somewhat shorter pointed bill and the white patch in the wings would rule out all wrens.

Resources Used

I have seen female Black-throated Blue Warblers before. I used my memory to recall the coloration and body structue of this bird.. The deeper chip note was something that I had not heard before, so I endeavored to get a look at the bird making the sound.

Previous Experience

I have seen female Black-throated Blue Warblers before.


Notes made DURING observation

Materials Available

No files uploaded.

Date Documentation Submitted

7/8/2019 5:09:00 PM

Location Map

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