Why is using the specific epithet necessary when discussing co-occurring weasels in places like Pennsylvania?

The common name 'weasel' is an umbrella term for at least two different species in the *Mustela* genus

In many geographic areas, such as Pennsylvania, local field identification relying solely on the common name 'weasel' leads to significant ambiguity because multiple species from the same genus (*Mustela*) coexist. Specifically, both the Long-tailed Weasel (*M. frenata*) and the Least Weasel (*M. nivalis*) may inhabit the region. Since these are reproductively isolated species occupying distinct ecological niches—one being significantly larger than the other—using their unique scientific names is essential for biologists to accurately document observations, track population dynamics, and discuss specific behavioral or morphological characteristics pertinent to only one species, thereby avoiding confusion inherent in generalized common terminology.