Food resource partitioning in syntopic nectarivorous bats on Puerto Rico

Understanding the dietary needs of syntopic species is essential for examining species coexistence and resource partitioning. We analysed stable isotopes of carbon (δ 13 C) and nitrogen (δ 15 N) to estimate the diet of two putative nectarivorous bats on Puerto Rico, the brown flower bat (Erophylla bombifrons) and the Greater Antillean long-tonguedbat(Monophyllusredmani).Isotopicratiosof δ 13 Candδ 15 Nwereobtainedfromwholebloodofbothspecies of bat and tissues of available plant foods and insect prey over 15 wk at the same locality. We used a concentration- dependent Bayesian mixing model to determine probability distributions of feasible dietary contributions for major potential foods used by each species of bat. Additionally, separate dietary estimates were conducted for males and non-reproductive,pregnantandlactatingfemalestodeterminedifferencesduetoreproductivecondition.Insectswere an important source of protein for M. redmani ,w hereasE. bombifrons obtained most of its protein from plants. In both species of bat, lactating females had lower assimilated nitrogen than males, suggesting more reliance on plants for protein. We observed no intraspecific differences in assimilated carbon among reproductive conditions. Flight and lactationareenergeticallyexpensiveandmayexplaintheincreasedconsumptionofhigh-energyfoods,suchasfruitor nectar,inlactatingfemalebats.ComparisonofisotopesbetweenE.bombifronsandM.redmaniillustratethedifferential use of food resources by these insular syntopic species of bat.