Date: 7/31/19 6:52 am From: <clearwater...> Subject: [obol] Re: Titmouse Oak or Juniper?
Apologies, I was not paying attention yesterday as I was working on a deadline, but I see my name was mentioned in the OBOL digest. And then I said, "Good grief!!"
This whole discussion and the angst ensuing from it seems to revolve around a dubious proposition:
That if hybrids have been found in the Lava Beds region of northeastern (almost north-central) California, in the Cascade-Siskiyou region (a region known for its biological complexity), that birds a hundred miles east of there, across a second major mountain range and out in the Great Basin proper, must also be hybrids.
The titmouse population in the Adel area is contiguous to a larger population in juniper woodlands in the eastern part of Sheldon National Wildlife Refuge. These and all others in Nevada, so far as I'm aware, are regarded as Juniper Titmouse, going back to the paper by Cicero (1996) which established the basis for the Juniper/Oak Titmouse split based on genetics as well as vocalizations and habitat preference.
A 2005 report by the Great Basin Bird Observatory summarizes the status of Juniper Titmouse in Nevada thus: "Throughout most of Nevada, except northeastern portion of Great Basin and southern portion of Mojave region." The Nevada Breeding Bird Atlas (completed in 2000) found Juniper Titmouse in widespread locations. I don't know of any documented occurrence of Oak Titmouse.
A further consideration is that Nevada has a north-south "grain." The mountain ranges run roughly north-south, perpendicular to the direction of Basin & Range extension. So patches of contiguous habitat also run north-south. There is fairly good connectivity of the Adel region (barely into Oregon at the base of the Coleman/Warner Rims). You can find titmice in the little pass at the south end of the Coleman Valley, just over the line into Nevada, and their habitat links pretty directly to the Little Sheldon area on the west end of Sheldon NWR, just to the south.
I wouldn't rely on eBird to settle this type of question. Better to look up this original paper:
Cicero, C. (1996). Sibling species of titmice in the Parus inornatus complex (Aves: Paridae). University of California Publications in Zoology 128:1-217
and start from there. My personal opinion is that there is no reason for list-oriented Oregon birders to panic over this one.