Adult males of the long-nosed bat (Leptonycteris curasoae) produce odoriferous “sebaceous” secretions in the interscapular region (dorsal patch), exclusively during the mating season (November–December). These dorsal patches might play a role in mate selection by L. curasoae in northern Venezuela. We evaluated differences between body traits of males with and without dorsal patches to determine whether these structures could be used by females as indicators of male quality, examined whether the size of the dorsal patch shows a relationship with other body traits during the mating season, and investigated the physical and behavioral development of dorsal patches. Thirty-seven percent of all males sampled (n  =  99) showed conspicuous dorsal patches during the mating season in November and December. Males with conspicuous dorsal patches had larger testes, smaller body masses, lower body condition indices, and lower ectoparasite loads than males without dorsal patches. Larger testes and lower ectoparasite loads suggest that the dorsal patch could be signaling male quality and readiness for mating. A typical dorsal patch covered approximately 1.7 cm² of a male's interscapular region, but size of this structure did not vary with any of the body traits examined. We describe a novel, stereotypic behavior performed by male L. curasoae, which we call “smearing behavior,” and suggest that this is associated with development of the dorsal patch because males appear to smear different body fluids onto this patch. We further suggest that sebaceous secretions in the interscapular region would not be the determining factor in dorsal patch development.