I had similar information in the 1970s that you had - also from PRBO: generally, LBDOs along the coast and SMDOs inland. Similar guidance for Yellowlegs: Greater along the coast and Lesser inland.

Not sure if things have changed since then.

Ed

On Sun, Oct 24, 2021 at 12:13 PM Peter Pyle <ppyle@...> wrote:

Hi Rusty and all -

The findings on substrate are correct but this and salinity are
confounded so it is difficult to then say that there is not a
salinity effect as well. However it goes, in winter, Short-billed
Dowitchers are quite confined to estuarine habitats here in the Bay
Area, whereas Long-billeds are more broadly distributed, including in
fresher water habitats. The two can occur together where creeks empty
into estuaries, though I still see the two species segregate in these
situations to some extent.

Personally I'd not feel that comfortable identifying this dowitcher
based on the one image. Nothing ever wrong with silent "SB/LBDO"s in
winter. I also have a hard time with the loral angle character - if
it is there, it seems quite dependent on the bird's disposition and
posture. For me the best thing in winter is bill length, with >60%
non-overlap, so among a flock of birds there will be some that are
out of range from the other species, and with experience you can get
these and then make assumptions about the rest of the flock.

Enjoy the rain, we've got a good one going,

Peter

At 10:46 AM 10/24/2021, rfs_berkeley wrote:

>What I had understood, from conversations years ago with PRBO (now
>Pt Blue) biologists is that substrate and not salinity is the
>issue.  That Short-billed strongly prefer an admixture of sand and a
>firm substrate; that Long-billed did well in muddy softer
>substrate.  He thought that Long-billed was the more abundant bird
>in many of the tidal marshes and actually the more abundant species,
>at least in the North Bay, in Winter.
>
>Now this information is perhaps 15 years old.
>
>Has substrate been discussed among shorebird biologists?
>
>    -Rusty Scalf
>
>     Berkeley
>
>>    * That sounds like a tidal spot? One migration is done,
>> Long-billed is typically not found in tidal/salt water areas.
>> Similarly, in the West Short-billed winters in tidal areas and is
>> absent from entirely fresh water spots. This is actually a very
>> solid rule but it blurs in migration, and is reliable in winter.
>>
>>
>>
>>
>
>

--

Edward Vine

Lawrence Berkeley National Laboratory
Building 90R2002
Berkeley, CA 94720-8136

Phone:     1-510-486-6047
Email:    elvine@...