Date: 3/13/18 9:37 am
From: Joel Geier <joel.geier...>
Subject: [obol] Re: Least Bittern and Upland Sandpiper
To address the questions and speculation about observer effort and
effect of wintering vs. breding habitat changes, let's take these one at
a time:

1. Least Bittern (LEBI):

Klamath Bird Observatory (KBO) surveyed systematically for LEBI and five
other secretive marsh species at numerous sites in south-central Oregon,
starting in 2008:
I'm not sure if they managed to cover all of the sites listed, or if
this study continued beyond 2008. In that year they had negative results
at Sycan Marsh, Klamath Marsh NWR, and Wood River Wetlands, but seem to
have detected LEBI at Malheur NWR ,near Frenchglen.

The Birds of Oregon: A General Reference (BOGR) species account for
LEBI, written by Kevin Spencer, cites Willett (1919) as finding a nest
at Malheur L., and reporting that LEBI was a common breeder there at
that time. The account also notes that conditions have changed since
then with the introduction of carp which "undoubtedly affected
invertebrate and amphibian populations." The species is also sensitive
to hydrologic conditions (water levels and contamination).

The BOGR species account mentions the lower Colorado River as a
wintering area. The formerly vast marshes where the Colorado River flows
(or used to flow) into the Gulf of California have been greatly
diminished due to water outtake for irrigation and urban use, so it
makes sense that populations in the western part of LEBI's nesting range
could be affected by loss of winter habitat.

2. Upland Sandpiper (UPSA)

As I mentioned previously, the Grant County Bird Club has had a
monitoring program for UPSA in the Bear & Logan Valleys and other known
nesting sites. So there has been pretty consistent, focused effort for
this species. The last time I asked Tom Winters about UPSA status in
Grant County, he was skeptical whether any were still using those sites.

Wayne Hoffman's sighting from the Riley Pond area, mentioned by Dave
Irons, sounds like a migrant situation. However the Grant Co. eBird
report that Trent Bray mentioned (as yet unconfirmed and thus hard to
find on eBird) gives a little more hope that a few might still be
nesting there.

The BOGR species account by Mark Stern cites reduction of forbs in
nesting meadows (cinquefoil is thought to be particularly important),
along with encroachment by pines and overgrazing of meadows as factors
that may have diminished nesting success. Habitat might also be lost
when water tables in meadows drop due to downcutting of streams, after
riparian vegetation is damaged by grazing. This is certainly evident in
the meadows around Big Summit Prairie, which produced a few reports in
the 1980s.

UPSAs winter in the pampas of central South America where no doubt they
face additional threats. However, according to the BOGR account the
North American population overall was stable or increasing (as of 2003).
If Oregon's population has diminished while the continental population
is stable or increasing, that seems to point the finger squarely at
issues on the breeding grounds.

Good birding,

Joel Geier
Camp Adair area north of Corvallis

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