Assessing sexual dimorphism in the common vampire bat, Desmodus rotundus

Sexual dimorphism in bats is understudied, with conflicting evidence across species and geographic regions. For Desmodus rotundus, the common vampire bat, previous reports on morphological sex differences have been inconsistent. This study aimed to assess sexual dimorphism in D. rotundus using a combination of contemporary field measurements and historical museum specimens. We analyzed six morphometric traits, including body mass, head length, body length, tibia length, ear length, and forearm length. Data were collected from 46 wild-captured individuals from five locations across Colombia in South America. Additionally, forearm length was examined in an expanded dataset of 490 specimens, including additional 444 individuals from museum vouchers collected over the past century. Principal components analysis and hierarchical clustering of the six-trait dataset showed patterns of differentiation between sexes, with partial overlap. Forearm length, analyzed independently in the full 490-specimen dataset, showed strong evidence of sexual dimorphism. Females had significantly longer forearms (mean = 61.8 mm) than males (mean = 58.5 mm), with non-overlapping 95% confidence intervals and a highly significant t-test result (t = −12.68, p