Morphological Differentiation and Identification of Peromyscus leucopus and P. maniculatus in Northeastern North America

External features of the tail and pelage, and quantitative cranial characteristics were used to discriminate Peromyscus leucopus from P. maniculatus ( n = 204) from northeastern North America. Species assignments were based on the phenotype of salivary amylase. Characteristics of the pelage and tail yielded correct identification of 55% of adult specimens. A previously published discriminant-function equation based on 11 cranial measurements correctly classified 66% of adults and 56% of specimens of all age classes. Two new discriminant equations were generated based on 12 and 11 skull measurements, respectively. The first equation correctly classified 100% of skulls in two separate datasets ( n = 164; n = 50), and the second correctly classified 94% in a single dataset ( n = 195).