We present the Limited-range Online Routing Problem (LORP), which involves a team of Unmanned Aerial Vehicles (UAVs) with limited communication range that must autonomously coordinate to service task requests. We first show a general approach to cast this dynamic problem as a sequence of decentralized task allocation problems. Then we present two solutions both based on modeling the allocation task as a Markov Random Field to subsequently assess decisions by means of the decentralized Max-Sum algorithm. Our first solution assumes independence between requests, whereas our second solution also considers the UAVs' workloads. A thorough empirical evaluation shows that our workloadbased solution consistently outperforms current state-of-the-art methods in a wide range of scenarios, lowering the average service time up to 16%. In the bestcase scenario there is no gap between our decentralized solution and centralized techniques. In the worst-case scenario we manage to reduce by 25% the gap between current decentralized and centralized techniques. Thus, our solution becomes the method of choice for our problem. Keywords: task allocation, unmanned aerial vehicles, max-sum, decentralized 1. Introduction Unmanned Aerial Vehicles (UAVs) are an attractive technology for largearea surveillance . Today, there are readily available UAVs that are reasonably cheap, have many sensing abilities, exhibit a long endurance and can communicate using radios. UAVs have traditionally been controlled either remotely or by following externally-designed flight plans. Requiring human operators for each UAV implies a large, specialized and expensive human workforce. Likewise, letting UAVs follow externally prepared plans introduces a single point of failure (the planner) and requires UAVs with expensive (satellite) radios to maintain continuous communication with a central station. These constraints are acceptable in some application domains, other applications require more flexible techniques. For instance, consider a force of park rangers tasked with the surveillance of a large natural park. Upon reception of an emergency notification, the rangers must assess the situation as quickly as possible.