We consider the problem of aggregating data at a mobile fusion center (fusor) (eg. a PDA or a cellular phone) moving within a spatial region over which a wireless sensor network (eg., fixed motes) has been deployed. Each sensor node generates packets destined to the fusor, and our objective is to develop strategies that can route the packets to the mobile fusor. For an arbitrary (possibly random) fusor mobility pattern over any connected subset of the sensor deployment area, we first derive upper bounds on the aggregation data rate (i.e., the uniform rate region from each sensor node to the mobile fusor), where we allow all sensor nodes to have complete knowledge of the mobility pattern of the fusor. We then consider aggregation data rates that can be achieved when the mobility pattern of the fusor is unknown to the sensor nodes. Surprisingly, we show that for a class of mobility patterns (random mobility over connected-compositions of convex sets of the deployment region, e.g. random walks over piece-wise linear sets), we can construct “universal” mobility-oblivious routing strategies that achieve aggregation data rates that are of the same order as the (mobility-aware) upper bound.