Hendra virus (HeV) spillover from Australian flying fox (FF) bats to horses is still a rare event. To understand some of the mechanisms driving the risk of spillover we developed a mechanistic model that we used to design an observational study in the interface where spillover occurs, the paddock. We selected a few of the model parameters to directly observe in the field and provide an estimate of how often Horses might interact with HeV. To do so we attached GPS trackers on horses vaccinated against HeV to track their movements. To record bat activity we deployed infra red cameras under trees that had bat activity and matched the information recorded by the cameras with live counts. Bat activity was used to simulate HeV excretion and decay with a published model (Martin et al 2015). With these data we estimated how often horses can interact with bats or HeV and identified areas of intervention to reduce the risk of contact with areas potentially contaminated with HeV.