Kathy, there’s a one-stop shopping venue for all your edification needs related to Birding By Ear for wood-warblers: earbirding.com
Here, Nathan Pieplow, an erudite sound recordist and expert birder, highlights many “ear birding” elements, including ways for you to easily read sonograms/spectrograms.

Please see his web site: earbirding.org and his recent book’s are excellent on this subject: a) Petersen Field Guide to Bird Sounds of Western N. America and b) Petersen Field Guide to Bird Sounds of Eastern N. America.

The above web site is so good that it gets a top rating from Warbler Guy’s advisory panel: me, myself, and I.

Seriously, reading and interpreting sonograms/spectrograms takes practice, but after a while you can
see the elements upon the page that originally looked like gibberish make sense.

Ergo, you’ll quickly have no problems identifying a song sparrow classic song via its sonogram in comparison to a common yellowthroat’s, and so on.

Other resources for identifying birds by sound and “ear birding” abound…..Some of my favorite are books by Dr. Donald Kroodsma, who authored the classic:
The Singing Life Of Birds.

Is warbler song easy to read on sonograms? Some people find them easier to comprehend than others. I think the above resources will help. My opinion is that some sonogram songs are easy to understand and others are more incomprehensible.

The Olive Warbler, Peucedramus taeniatus,  is a small passerine bird. It is the only member of the genus Peucedramus and the family Peucedramidae.

Breeding from southern Arizona through New Mexico and south into Mexico and Nicaragua, the Olive Warbler is the only member of the genus Peucedramus and the family Peucedramidae. All our other New World warblers in the continental USA are in the Parulidae family (except for rare to occasional vagrant sightings of Old World Warbler sightings — among them being Arctic and Dusky Warbler).

The Olive Warbler status in its one-member family is distinctive in that it’s the only bird family endemic to North America (including Central America). Before it was classified into its current family, this warbler was considered a Parulidae, but DNA studies suggest that it split early in its evolutionary history from the other related passerines prior to the differentiation of the entire New World warbler/American sparrow/Icterid group.
Where should you look for this species?

Like many other New World warblers, it is an insectivorous species of coniferous forests.
According to the iBird Pro app I used to interpret its distribution range, Olive Warbler is restricted to breeding in central/east-central Arizona and a small portion of southwestern New Mexico. It’s non-breeding season range includes southern Arizona most of western Mexico and a restricted area of northeastern Mexico immediately south of Texas.

Though it is often said to be non-migratory, most New Mexican birds typically leave the state from November to late February.

(The Black-Throated Gray Warbler in the above photo is one of five species within the Black-Throated Green superspecies group.)

Thanks for the query, Ms. Jones (in Santa Barbara, CA).

Think of a superspecies as a group of related species that evolved from a common ancestor, but live in distinct ranges apart from each other. A good example of a superspecies is the Black-Throated Green Warbler group that includes this species as well as Townsend’s, Hermit, Golden-Cheeked, and Black-Throated Gray Warblers.

Each of the latter four species in the above group is thought to have evolved from its Black-Throated Green ancestor. As this species expanded from its southeastern USA deciduous forest territory into coniferous forest created by the most recent glacial advances, isolation occurred among populations. As generations of separated populations slowly spread west and north throughout lower North America, each population became a divergent “island.” Gene flow ceased as reproductive isolation caused speciation to occur over eons. The resulting five species share various field marks, but also express their own unique characteristics.

Nonetheless, despite their status as species, hybridization sometimes occurs among species within a superspecies, including the Black-Throated Green superspecies wherein populations of Townsend’s and Hermit hybridize in Oregon and Washington. To simplify, where both species occur, over time Townsend’s appear to usually dominate and increase in number.

More technical, the five species within the Black-Throated Green superspecies have parapatric distributions. That is to say, each of the five species has ranges that do not significantly overlap but are immediately adjacent to each other (and/or occur together in a narrow contact zone, with the aforementioned reference to Townsend’s and Hermit Warbler hybridization a scenario where overlapping occurs).

To learn more about this subject, read a classic article by R.M. Mengel titled “The probable history of species formation in some northern wood warblers.” One source where this article appears is in a 1964 edition of “Living Bird” (page 943).