Infectious disease is an increasingly potent conservation threat to wildlife worldwide, causing local extirpation, modulating community dynamics, and decreasing host ranges. Infection with trypanosomes may be one of the most significant risks facing the critically endangered Javan rhinoceros (Rhinoceros sondaicus) in Ujung Kulon National Park (UKNP) of Java, Indonesia. The Javan rhino population is highly susceptible to the stochastic effects of disease: the population size is small (27-44 individuals); it is sympatric with putative Trypanosome reservoir hosts such as water buffalo (Bubalus bubalis) and banteng (Bos javanicus); and Trypanosomes are multi-host vector-borne pathogens that are known to cause high mortality in naïve species, including Asian rhinos. Trypanosome parasites have been identified in water buffalo from villages in the park and implicated in die-offs of Sumatran rhinos, yet information regarding basic vector biology (including species within the family Tabanidae and source of host blood meals) has never been studied in the region. The threat posed to the Javan rhino population by Trypanosomes is thus poorly characterized. We will define, for the first time, the vector biology that regulates transmission patterns for Trypanosoma evansi infection among 3 sympatric ungulates (buffalo, rhino and banteng) in UKNP. This project is relevant to MAF because it addresses an urgent health threat to the rarest large mammal on earth that can be solved through new techniques in medical entomology combined with training of a future wildlife health professional.