Leptonycteris yerbabuenae is a bat with a distribution range from southern USA to El Salvador. A distinctive feature of the species is the seasonal accumulation of subcutaneous fat. Since this specie does not hibernate, it has been speculated that this energy reserve is used for migration and reproduction or when food availability decreases. As the role of fat in populations of southern Mexico is unknown, we carried out this study to determine the fat accumulation pattern and the role it plays during an annual cycle in a resident colony of this taxon. Results show that males follow a seasonal pattern, which begins with fat accumulation in February and peaks in May, right when the mating period begins. After this period, the amount of fat steadily decreases and disappears during November-January. We also found that the body and testicular mass are positively related with the amount of accumulated fat and with the development of an interscapular dorsal patch. Data suggest that stored fat is used for reproductive purposes and as an energy reserve to stay longer in the breeding colony, and that the interscapular dorsal patch may be taken as the evidence of reproductive success.
Keywords: Body mass, Dorsal patch, Fat pattern, Mating behavior, Subcutaneous fat, Testicular mass.