Yellow Warbler
Setophaga aestiva
Riparian willows and streamside thickets. The plain yellow face and yellow tail-spots separate it from the drab Orange-crowned and the black-capped Wilson's (see pairs).
In spring, the males hand themselves to you — face pattern, wingbars, and how much yellow name most of them in seconds. In fall, the drab immatures are the famous trap. This keys the bright birds cleanly and tells you, honestly, where the drab ones stop keying.
One objective cut splits our warblers nearly in half.
No wingbars — mostly yellow or olive. The big group, and the hard one. Yellow, Wilson's, Orange-crowned, MacGillivray's, Nashville, Virginia's, Common Yellowthroat, the Chat.
Two pale wingbars — grey, black & white. Only three locals: Yellow-rumped, Townsend's, Black-throated Gray. Wingbars isolate them instantly.
Among the plain-winged crew, the split is the face (§03) plus how far the yellow spreads — head-to-tail (Yellow), just the throat and undertail (Virginia's), or a masked/hooded face (Yellowthroat, MacGillivray's). Two odd ones sit outside the system: the huge Chat and the flash-patched Redstart.
Tap through to a name. Cleanest on a bright spring bird.
The full key — follow the arrows.
Among the plain-winged yellow crew, the face is the whole game.
Ordered common → rare. Amber box = the clinching (bright-plumage) mark.
Setophaga aestiva
Riparian willows and streamside thickets. The plain yellow face and yellow tail-spots separate it from the drab Orange-crowned and the black-capped Wilson's (see pairs).
Setophaga coronata
Our default migrant and wintering warbler, often in loose flocks. The yellow rump ("butter-butt") shows in every plumage; Audubon's vs Myrtle is a tidy sub-ID.
Geothlypis tolmiei
Skulks low in brushy tangles and regrowth. Broken arcs and a grey throat separate it from the complete-ringed, yellow-throated Nashville (see pairs).
Cardellina pusilla
Active and tail-flicking in willows and thickets. The cap is unmistakable on males; plain females are told from Yellow by the lack of chestnut streaks and a beadier look.
Leiothlypis celata
"The absence of field marks is the field mark." Note the yellow undertail and faint streaking — the hardest of the plain-winged crew, especially in fall (see pairs).
Leiothlypis ruficapilla
Migrant in scrub and woodland edges. Complete eye-ring + yellow throat separate it from MacGillivray's (broken arcs, grey throat) and the greyer Virginia's (see pairs).
Leiothlypis virginiae
A dry-slope breeder in scrub oak and pinyon-juniper. Grey with only limited yellow separates it from the extensively-yellow Nashville (see pairs).
Setophaga townsendi
A conifer migrant. The yellow face with a dark ear-patch separates it from the black-and-white Black-throated Gray (see pairs).
Setophaga nigrescens
Breeds in scrub oak and pinyon-juniper. Almost no yellow — just the lore dot — which separates it from the yellow-faced Townsend's (see pairs).
Geothlypis trichas
Cattails and wet edges. The mask is diagnostic on males; plain females show a yellow throat and warm face — habitat and skulking behaviour help.
Icteria virens
Not a true warbler (its own family, Icteriidae). Big size, thick bill and white spectacles are unmistakable — more often heard than seen in riparian tangles.
Setophaga ruticilla
A scarce, local riparian breeder and migrant. The flashing wing-and-tail patches and constant tail-fanning are unlike anything else here.
Bright-bird pairs; the fall drabs are their own problem (§06).
Orange-crowned vs Yellow
Both plain-winged and yellowish. Yellow is bright and clean with a big dark eye and yellow tail-spots; Orange-crowned is dingy and olive with faint blurry streaks and a faint split eye-arc. If it looks washed-out and marks-free, it's Orange-crowned.
Nashville vs MacGillivray's
Both grey-headed and yellow-bellied. Nashville has a complete bold eye-ring and a yellow throat; MacGillivray's has broken white arcs and a grey hood that includes the throat. Throat colour alone often settles it.
Nashville vs Virginia's
Both grey-headed with a white eye-ring. Nashville is extensively yellow below; Virginia's is mostly grey with just a yellow breast-patch and yellow undertail, and it wags its tail. Extent of yellow is the cut.
Townsend's vs Black-throated Gray
Both wing-barred with a black throat (male). Townsend's has a yellow face and breast with a dark cheek; Black-throated Gray is black, grey and white with no yellow but a single tiny lore dot.
Wilson's vs Yellow
Both bright yellow and plain-winged. Male Wilson's wears a neat black cap; Yellow shows chestnut breast streaks (male) and yellow tail-spots. Capless females: Wilson's is beadier-eyed and greener above.
MacGillivray's vs Common Yellowthroat
Both dark-faced skulkers. MacGillivray's shows a grey hood with broken white arcs in brushy uplands; male Yellowthroat has a solid black mask and lives in marsh. Females: go by structure and habitat.
The fall ceiling, the chase-birds, and the vagrants.
Everything above keys cleanest on a bright spring bird. September immatures — washed-out Orange-crowned, dull first-fall Yellow-rumped, greenish young Wilson's and Nashville — lose their marks and genuinely overlap. Get the wingbar state, the face remnants, and the undertail, then reach for a dedicated reference (Dunn & Garrett, Warblers). Don't force a drab bird to a species because the key wanted one.
A few eastern vagrants show all-years peak frequencies near 1% — Hooded ~1.5%, Canada ~1.1%, Black-throated Blue ~1.0%, Chestnut-sided ~0.9%. Those aren't regular occurrence; they're single staked-out birds that many people chased in one week. Treat every one as a rarity, not a tier.
eBird shows these in the county; the 2020 UBRC checklist lists them as not recorded and review species.
These have occurred but the UBRC requests documentation. The likely-to-appear ones:
Reported and not review, so they belong on your list — they're simply too scarce or too distinct to card here: