The selection of nest sites and nesting material may have important implications for avian reproductive behaviour and performance. Nest construction may involve costs arising from transporting material that may be reduced considerably if nest materials are located close to the nest site. Eurasian Nuthatch Sitta europaea nests in our nest box study area are mainly composed of pine bark flakes or alternatively of strips of bark of the widespread shrub Cistus laurifolius, with variable amounts of mud being used for plastering the entrance. Several small streams run through the area — an oak Quercus pyrenaica forest with a few scattered pines Pinus sylvestris. Here we show that Nuthatches collected pine bark only when nest sites were situated close to pines, used more mud when breeding close to streams and selected nest sites closer to streams than a sympatric species not using mud, the Pied Flycatcher Ficedula hypoleuca. Nuthatches used pine bark only when there was a pine tree less than 100 m away from the nest box and selected Cistus bark when transport distance was greater. We suggest that the selection of nest sites and nest materials in this species may be constrained by the costs of transporting nest material.