Date: 4/3/17 9:34 pm From: Joel Geier <joel.geier...> Subject: [obol] Nashville Warbler breeding status in Coast Range
Following on Dave Irons' and Tom Mickel's comments, I'll just add my own impressions on the breeding status of Nashville Warblers based on 20-some years of paying attention to things in Benton and Polk Counties.
First off, sightings of Nashville Warblers are generally sparse on the west side of the Willamette River at this latitude, even during the season when migrants are moving through. About 15 years back Barb Bellin (who grew up in Philomath and still has one of the longer lists for Benton Co.) told me that she was still looking for her first Nashville Warbler in Benton County. I've seen a few but I always count them as a highlight for the year, since they're far from guaranteed.
They're even harder to find in Polk County. All of my Polk County sightings except one (which I'll get to in a bit) have been within 5 miles of the SE corner of Polk County.
Migrants are seen (sparsely) through the middle of May. We've had a few singing birds that showed territorial behavior in early May. However, reports of them staying at a single location for multiple days are very scarce. The only such report that I'm aware of from Benton County is a male Nashville Warbler that sang at Bald Hill Park just west of Corvallis, from 26 May through 5 June in 2012 (as reported by Don Boucher and Bill Proebsting).
There have been a few other isolated reports from late June or July which might represent post-breeding dispersal. I encountered a male Nashville Warbler near Laurel Peak (Polk County Coast Range) during the late part of the breeding season in 1999. There have been a handful of similar late-season/post-breeding records from Marys Peak in Benton County.
So I would say, there is still no solid evidence of Nashville Warblers breeding in the Coast Range in either Polk or Benton County, though there are a few hints that they might nest very sparsely.