Probably not but…
Western and eastern is a misleading term when it comes to many species. Personally I like distinctive names for birds, leaving the scientific name to fill in the other details. In the west our regular Nashville Warbler is slightly different in plumage and habits, it was even called Calavera’s Warbler at one time. The field and specialist guides are rather vague on the specific differences in plumage for ‘western’ Nashville although all agree that it is a regular little tail pumper. Ours doesn’t, so a late season tail-pumping Nashville in Nova Scotia is one to look at twice.
At the end of October 2016 I came across not one but two Nashville Warblers on different parts of Cape Sable Island. The first looked standard and behaved accordingly. The second was a pumper and looked to have more extensive grey on the back and a whiter lower belly, I didn’t get to see the rump. I blogged it at the time but recently read a few things, such as the tail pumping habit of ‘Calaveras” and suspect the bird may have been of, or at least showing the behavioral characteristics of the western form. Ian McLaren in ‘All the birds of Nova Scotia – Status and Critical Identification’ notes four examples of putative western birds here.
Here are two images of the Fish Plant Road, CSI tail-pumper from September 26th 2016. Due to my own stupidity I managed to delete the originals and the doc shots of the other Nashville from the day so all I have is edited versions of the interesting one.
Below is a map of the respective ranges of eastern and western summer and winter ranges, courtesy of Wikipedia.
By Cephas – Birds of North America OnlineAmerica-blank-map-01.svg, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=12860116
There are some pitfalls in identifying late Nashville Warblers, here is a link to an interesting warbler by Blake Maybank.
Below a few shots of an eastern Nashville from September 6th 2016 near Halifax.
And another eastern Nashville from Cape Sable Island, September 30th 2016.
A shot of a bright autumn QC bird from September 9th 2007
A shot of a known western, taken in Arizona on September 9th 2011. Interesting that the eye-arcs on this bird are broken.
Lastly an August 26th 2006 Nashville in QC, well sort of, it does look a bit odd, sorry it is not quite up to the regular standard..