New World wood-warblers (that are not closely related to the various Old World warblers in the Eastern Hemisphere (e.g., Europe, Asia) are often identified to number as 112-115 species, occurring among 24-26 genera. The centers (or “epicenters”) of their breeding areas occur in eastern North America, the West Indies, Mexico and Central America, and Andean South America. The majority of northern-latitude breeding species migrate, but many island and tropical species are sedentary. Many of these latter species remain close to their birthing areas or perform short-distance, post-breeding altitudinal/elevation migrations.

As for myself, I often see 20-30 wood-warbler species during early May when I return to homecoming birding forays in the Midwest (and, concurrently, attend the annual Wisconsin Society For Ornithology conference). This year I did not return in spring (due to the virus), but in 2019 I was lucky to visit Wisconsin for a week-long June jaunt that yielded merely a single digit wood-warbler species total.

Likewise, my birding efforts in southern Wisconsin in 2019 provided challenging warbler conditions, with Milwaukee County nearly devoid of warbler detections, except for probable nesting species such as American Redstart, Mourning Warbler, Bay-breasted Warbler, and Yellow Warbler. In contrast, my n. CA residency, yields more warbler species during the breeding season — a result that surprises many people because the West is thought to host far fewer warbler species. Last month during a two-day to the Sierra, I was pleased to detect eight warbler species.

Then there's Marin County (Bay Area) where I live. Here, I am also able to typically detect at least eight warbler species annually.