It's an interesting dilemma, isn't it? Because you are telling people
identification should not be based on field marks alone but also on
probability, which is a slippery slope situation. Personally, if someone does
not detect enough information about physical or vocal features to reach an
identification to species level, I think the best approach is to use a slash
option even if one part of the slash (e.g., Alder Flycatcher in Oregon) is
highly unlikely, but I understand the idea that there is some point at which
the probability is so low it almost becomes excessively conservative to use the
slash.
One option we have used in Benton is to proceed with identification to species
level of the expected species then add comments indicating a less likely
alternative could not be eliminated based on the views. In our cases, those
were flyby ibises that couldn't be seen well enough to eliminate Glossy and
female/imm Black-chinned Hummingbirds where details couldn't eliminate
Ruby-throated. WFIB and BCHU are both very rare here, too, so the difference in
probability is not as extreme as a Willow vs Alder situation.
A more similar situation would be observers in Corvallis reporting
California/Woodhouse's Jay. Technically speaking, if observers saw a scrub-jay
poorly, they couldn't eliminate Woodhouse's based on fieldmarks alone. I
thanked them for being careful, then told them it was ok to assume all
scrub-jays are Cals because we've never had a record of Woodhouse's (nor
Florida or..... ;) ). The point is, encouraging observers to focus on field
marks first and not probability is critical in my opinion. They can always add
notes to explain their decisions. When they rely too much on guessing
probability instead of looking or listening critically then they can create
much worse problems, or miss amazingly interesting things. The apparent
frequent mimicry in songs of Hermit and Black-throated Gray Warblers comes to
mind. Assuming Hermits are in one habitat and BTYW are in another is incorrect
and masks some fascinating stuff going on there. Best to work hard at getting
dialed in on the right fieldmarks or sounds, or use the slash.
All the best,
Doug
PS Please forgive typos or excessively long sentences. Still recovering from an
intense field season.
On Jul 5, 2017, at 2:45 PM, Russ Namitz <namitzr@xxxxxxxxxxx> wrote:
I recently had this issue with two out of state birders that work for the
Portland Audubon Society at Malheur. They were introducing things like
White-faced/Glossy Ibis and Willow/Alder Flycatcher into their checklists. I
invalidated most of these designations and emailed the observers to ask them
not to do this. This is only useful if both species are known to occur in an
area with regular frequency.… In my opinion.
Russ
Sent from my iPhone
On Jul 5, 2017, at 12:39 PM, Vjera Thompson <dmarc-noreply@xxxxxxxxxxxxx>
wrote:
Hello all,
I was curious about the eBird HQ policy on invalidating "slash" category
birds if one is likely and the other is unlikely, so I asked Brian this
morning. He recommends steering people toward the more conservative slash
(Hermit/BTG) as Dave did below but said that we technically don't need to
invalidate as long as one of the "slash" birds is likely. Here's a related
eBird help article, although it doesn't talk about what to do if one of the
options is unlikely:
http://help.ebird.org/customer/en/portal/articles/1010550-do-i-have-to-be-an-expert-to-contribute-to-ebird-?b_id=1928
I'm at work so can't look right now, but have people been adding the
Townsend/Hermit slash to their checklists, or is it already in the filter?
If the unlikely slash is in the filter, perhaps we should remove it so
people aren't likely to choose it?
I've included the original message in case anyone here didn't see it on OBOL.
Vjera
From: David Irons <LLSDIRONS@xxxxxxx>
Date: July 4, 2017 at 7:22:50 PM PDT
To: OBOL Oregon Birders Online <obol@xxxxxxxxxxxxx>
Subject: [obol] Reporting of "slash" category Townsend's Warblers in the
Oregon Coast Range
Reply-To: LLSDIRONS@xxxxxxx
Greetings all,
This is a bit of an esoteric topic. I am in the process of doing some eBird
reviewing for Washington County and I have come across several recent
(June–July) reports of warblers reported list birds as either
Townsend's/Hermit or Townsend's/Black-throated Gray. These reports involve
heard only (singing) birds. The songs of this threesome of species are
highly variable geographically in terms of tone and pattern. Local dialects
are many, particularly for Hermit and Black-throated Gray. In many cases it
is hard to put a name to unseen birds. This is where is it is important to
understand range and probability.
Hermit and Black-throated Gray Warblers are abundant breeders in the Oregon
Coast Range. Hermit Warblers predominate at higher elevations and upslope
habitats that are conifer dominant. As a general rule, Black-throated Grays
tend to be found at lower elevations in habitats with a strong mix of red
alder and big leaf maple interspersed with conifers. This includes
streamside sites, where red alder is often the dominant tree species.
We are near the southern end of the breeding range for Townsend's Warbler,
which does not regularly summer or breed in Oregon's Coast Range. Some
migrants move north through the Coast Range, but after about the third week
of May I would be surprised to find a Townsend's anywhere in Washington
County. A June–July bird would be most surprising in the Coast Range, or in
the upslope areas closer to Portland (Forest Park and the West Hills).
In my opinion, using either the Townsend's/Hermit or
Townsend's/Black-throated Gray slash categories for the reporting of
unidentified singing Setophaga warblers in these habitats is potentially
misleading, as it suggests the possibility or likelihood that Townsend's is
present in the Coast Range and surrounding ridge lines at this season. In
my experience, they are not. For heard only Coast Range warblers whose
songs can't be identified, I would recommend leaving them either unreported
or assigning them to the Hermit/Black-throated Gray slash category. Use of
any slash category that includes Townsend's is the least accurate way to
report such birds. I can't in good faith validate such sightings, unless
the observer supplies an audio recording that clearly suggests Townsend's
Warbler.
Some sources suggest that Townsend's and Hermit songs are hard to
distinguish and this may well be true in the contact (hybrid) zones where
both species breed. There is a significant zone of breeding contact, which
stretches along the crest of the Cascades (mostly higher elevation eastern
slopes) from Deshutes County, Oregon north to Yakima County, Washington.
Hybrids are fairly easy to find in this contact zone and I would expect
that sorting out the vocalizations of unseen birds in this overlap zone is
more of a challenge than it is elsewhere. Away from this hybrid zone and
with seen birds that are apparent non-hybrids, I have never had much
trouble telling Townsend's and Hermit songs apart. To my ear, Townsend's
songs sound a bit slower, more slurry and generally less strident. Their
songs generally lack the two hard notes at the end that I hear in most
iterations of the Hermit Warbler song. Hermits tend to sing faster in
crisper, slightly higher-pitched notes. They rarely sound "drunk," which is
how I often characterize the pattern of Townsend's Warblers, particularly
those heard singing away from breeding grounds and during migration.
I post this in hopes of nipping this reporting trend in the bud and saving
us (Shawneen and me) some work. Shawneen and I like to query observers and
get their feedback before invalidating sightings out of hand.
Dave Irons
Beaverton, OR
Washington County eBird Reviewer
