Catching Gnatcatchers in Arizona

Four species of aptly-named Gnatcatchers occur in North America.

Blue-gray Gnatcatcher, with Gnats

One, the California Gnatcatcher, is limited to a small area of southern California and is considered a threatened species. Another, the Black-capped Gnatcatcher, is a rare visitor and nester in southern Arizona. The other two are ubiquitous in the core of their respective ranges and the range of one, the Blue-gray Gnatcatcher, overlaps those of the Black-tailed and Black-capped Gnatcatchers.

Although Black-tailed prefer lower elevation scrublands (Birds of North America, Cornell Lab of Ornithology), that species as well as Black-capped and Blue-gray can be found in higher elevation wooded areas and canyons. Thus, if you are in southern Arizona, you have three options to consider whenever a sprightly, blue-gray, insect gleaner appears in your view. Of course, with practice these species are most readily distinguished by their different vocalizations, but here we'll just look at field marks.

Blue-gray Gnatcatcher

Black-tailed Gnatcatcher

Black-capped Gnatcatcher

The first regular eBird reports of Black-capped Gnatcatcher in southern Arizona began in 1997, although there are eBird reports in the area since the early 1970's. None were reported in 1998 but in 1999 reports were filed from three locations between February and July. Beginning in 2006 and in most years since, the BCGN has been recorded in every month of the year, although still rare and found at specific locations such as Madera Canyon and Florida Canyon.

So birders still look for BCGNs for year lists and life lists. When Jay and I encountered a couple of birders at Madera Canyon, they were looking at what they thought were Black-tailed Gnatcatchers, but hoping for Black-capped. Knowing of recent reports, and after a few minutes chase, we confirmed the identification of a pair of Black-capped Gnatcatchers, apparently scouting out nest sites.

The key field marks for the BCGN are the size of the bill, the extensive white underside of the rectrices, and the black cap in breeding plumage. Individually, each of these can overlap with, or differ only slightly from, Black-tailed or Blue-gray Gnatcatchers. So some care is necessary to look at the combination of field marks, but with a little practice distinguishing these confident and energetic sprites becomes straightforward.

Tail: Note that Blue-gray and Black-capped both have white undersides to the rectrices.

Blue-gray Gnatcatcher Undertail

Black-capped Gnatcatcher Undertail

Black-tailed Gnatcatcher Undertail

Bill and Cap: Note that Black-capped bill can look smaller when head feathers are erect and that black caps are not full in basic plumages. While Black-capped show some white eye ring feathers, and they do not develop the bold eyeing found on both Black-tailed and Blue-gray.