Documentation of Lesser Black-backed Gull

Observer Information

Reporter:  Kristi Streiffert  223 Sierra Vista Street,   Durango, CO  81301
Other Observers:  Robert Winslow, Katy Shirley, Lisa Wilk, Kurk HIllman

Species, Date, Time and Location Information

Species:  Lesser Black-backed Gull
First Date/Time:  4/1/2022 10:00:00 AM
Last Date/Time:  4/1/2022 11:30:00 AM
Duration (total time in view):  1 hour
County:  La Plata
Specific Location:  Pastorius State Wildlife Area
Number:  1
Age:  Adult
Sex:  Unknown
Plumage:  Breeding


Pastorius Lake

Viewing Conditions

Optics:  Scope
Distance:  50 to 100 yards (photo at 50 yards)
Light:  Excellent

Description of the Bird

I was looking for a California Gull in with the regular Ring-billed Gulls. I found a gull the same size as the ring-billed, with yellow legs and red on the bill. But the back was not the gray it should be for a California. It was a lot darker. So I took a picture and found some other birders to discuss it with. They said they noticed the darker, blacker back, but that they still thought it was a California. I did not agree and asked them to send their pictures around for confirmation. We all sent pics to various people and they agreed this was a lesser black-backed gull. The photo I will attach is mine, and not very good.

But Robert Winslow will load his photos on ebird and they are make it clear. Please let me know if you need to have him send the photos directly to you or if the ebird list photos work. 

Similar Species Discussion

California - wrong color back.

Western - not enough white on ends of feathers. 

Resources Used

We asked Jason

St Pierre to look at Robert Winlow's photos. 

My (only so-so) photo was sent to Mark Holmgren and he called it Lesser Black-backed from that photo. 


I also used a Seabirds of the World book and Sibley.  


Previous Experience

Not a lot, that is why I asked several others to look at the photos. 


Review of photos

Materials Available

Photographer: Kristi Streiffert


Date Documentation Submitted

4/3/2022 9:26:00 AM
Click left or right edges of photos to move through all; click outside image to close

Location Map

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2) No specific coordinates are available but the location is mappable.
3) A generic location with no specific coordinates is mapped to the center of the reported county.

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