I have little (perhaps no) doubt that this species has been 
over-reported in Vermont, especially in spring. I have birded in this 
state for nearly fifty years and have seen (to my satisfaction) 
Philadelphia Vireo perhaps five or six times during spring migration. 
Quite frankly, I would NEVER identify this species on the basis of song 
alone  - I know of at least three experienced birders besides myself who 
have admitted to being positive a singing bird was a Philadelphia Vireo 
only to find a Red-eye when the bird showed itself. Ken is absolutely 
correct when he emphasizes using multiple criteria when identifying this 
species. In fact, that is an important guideline for identifying any 
difficult and/or rare species.

As to the bird Ken describes in his posting, I would say bravo for a 
very careful observation and description - but I would also say this: I 
would not conclude that the bird you saw was a Philadelphia Vireo. It 
may well have been a Phialdelphia but, as you say yourself, it "looked 
very much like a Warbling Vireo." Further, you state explicitly that you 
"could not discern any yellow" on the breast - but that is the one field 
mark I would insist on for safely identifying this species. To me this 
is a case where I would have to leave the bird unidentified; that is, it 
was either a Warbling Vireo singing a strange song or an unusually drab  
Philadelphia Vireo without showing its trademark yellow on throat or 
breast. If I had to guess, I would probably agree this bird was a 
Philadelphia (some of the drawings in Sibley look like your bird even 
though his text emphasizes a yellow throat) but to me this is a case 
where I think the observer should admit to uncertainty.

Fred Pratt

On 5/30/2019 10:45 PM, Ken Copenhaver wrote:
> Hi Bridget,
>
> I'm no expert on this species, but here is my report on a PHVI that I
> observed on 5/16/18 at Fairfield Swamp WMA -- French Hill Access.  I think
> it shows my thought process in narrowing it down to a PHVI vs. REVI:
>
> "Compared with Red-eyed Vireo: song slower, weaker, less insistent,
> choppier, more pauses; dark eye line and light eyebrow stripe were barely
> noticeable; less active than typical REVI; body more compact, less sleek.
> Clear, pale breast--could not discern any yellow. Looked very much like a
> Warbling Vireo; If it hadn't been singing, I would have assumed it was a
> WAVI. I listened to this bird for about 10 minutes and watched it high in a
> tree for several minutes, during which I had some clear views of its head
> and breast."
>
> I would add that it's easy to jump to conclusions on this species, so I
> think it's important to distinguish it from REVI by more than one criteria,
> including song, appearance, and behavior.  In this case, it was the
> non-typical REVI song that caused me to look at this bird more closely.  I
> was fortunate that it stayed in view long enough to get a good look at it.
> There might be others who are more experienced with PHVI and can ID it more
> readily, but for myself, I want to see several factors before declaring it
> a PHVI.
>
> --Ken Copenhaver
>
> On Thu, May 30, 2019 at 10:19 AM Bridget Butler <[log in to unmask]> wrote:
>
>> Greetings All!
>>
>> I feel like I'm seeing a number of reports on Philadelphia Vireos in a
>> number of different places recently.
>>
>> I've not much experience with this bird and have been reading up on tips
>> for identifying the bird (including studying images) in relation to other
>> vireos and warblers like the Tenessee Warbler. I'm wondering if I'm seeing
>> them but just not really locking in on an id.
>>
>> Wondering if those of you with experience with this bird might share your
>> own thinking on how to tease this bird out from others? What do you look
>> for or notice in terms of both plumage AND behaviors?
>>
>> Thanks in advance!
>> Bridget
>>
>>
>> *Bridget Butler*
>>
>> *Bird Diva Consulting*
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