Tuesday, September 19, 2017

Just How Common Is A Black-throated Gray Warbler . . .?

. . in the Bay Area?

. . . at this time of season?

I put the question to the EBB_Sightings Yahoo Group: "I was fortunate to see a Black-throated Gray Warbler at Mortar Rock Park in Berkeley the other day. Audubon page says the bird is widespread and common. I've only seen this bird one other time, at Sibley Volcanic Regional Preserve a couple of years ago. Does anyone see a Black-throated Gray Warbler commonly?"
I fielded three responses:

Judi S. said, "I think they are more often seen around here during fall and spring migration. I saw 2 together in Wildcat about 10 days ago."

Makes total sense. I wonder if those two are her only sightings? The adult female I saw was accompanied by a male consort, who largely stayed hidden, barely affording a flitting glance. But it ups my total to three, actually!

j ellis reported seeing the birds "only occasionally during migration. SF Botanical Gardens, Coyote Hills RP and Ardenwood Farms RP in Union City is where I see them this time of year."

So j seems to spot them fairly frequently, depending on migration patterns, and specific locations in the Bay Area.
Kay L., always knowledgeable, wrote that "Black-throated Grays may be common and widespread somewhere; but certainly not in the Berkeley area. Don't know which Audubon page you're referring to; but I'd tend to distrust the distribution comments for any species unless the site is specific to a fairly narrow area. (For example, if the site were focused on birds of the East Bay, and had comments on frequency or distribution, I'd be inclined to trust it more than a similar site that talked about all of California, or the whole United States.) FYI, neither the Alameda or Contra Costa County Breeding Bird Atlas show any indication of 'widespread' or 'common'. Like you, and me, I think most Bay Area birders consider it a treat to see one of these birds."

So, based on my small sample size, the jury is out: Black-throated Gray Warblers tend to show up semi-(ir)regularly in the Bay Area, but rarely in Berkeley. If lucky and diligent, and of course with specific timing, the birds might be seen a handful of times during the spring and fall migration periods.
My tally over the years = a grand total of two sightings, three birds. So, which is greater? The odds of me being in the right place at the right time, on two occasions? Or, the odds of me either being or not being in the right place to not spot them? The latter, for most certainly, I've been in many places at the right time, but, possessed of poor timing, I simply have not spotted more of the B-t Grays, or any number of other so-called rare birds passing through the Berkeley area during spring or fall migration - such as the Northern Waterthrush or Western Kingbird.
eBird's Occurrence Map for Black-throated Gray Warblers is an animated gif map that distributes their presence in accordance to preferred breeding locales, like a kaleidoscope of movement over time, through the seasons during different times of the year when they move to and fro to take up residence in Douglas Fir, Juniper and Pinon Pine in the desert Southwest, as well as the Sierra Nevada and the Pacific Northwest.

Evidently, they're common avidenizens of North America, but to see them in the Bay Area, and especially in Berkeley, I have to side with Kay L., for birder enthusiasts, it is special to spot one of pretty, fairly rare birds.