The Tamaulipas Pygmy-Owl is a newly-recognized species. Previously this population were classified as subspecies of the Least Pygmy-Owl (Glaucidium minutissimum), although now the name Least Pygmy-Owl is applied only to the birds in eastern South America. The Tamaulipas Pygmy-Owl has a very restricted geographical distribution: the range is centered on southern Tamaulipas and eastern San Luis Potosí, in northeastern Mexico, although possibly this species will be found farther south. This species overlaps geographically with the slightly larger Ferruginous Pygmy-Owl (Glaucidium brasilianum), but the Tamaulipas Pygmy-Owl occurs at higher elevations, and is more closely associated with humid forest and adjacent tall second-growth, rather than the more open areas preferred by Ferruginous. Tamaulipas Pygmy-Owl also is very similar to the Central American Pygmy-Owl (Glaucidium griseiceps), which occurs north to southeastern Mexico; these two species are believed to be allopatric, however. Despite its small geographic range, this species is not considered to be a threatened species. As is typical of Glaucidium, the Tamaulipas Pygmy-Owl is partially diurnal and hunts for invertebrates and small vertebrates, but there is very little information available about its biology.