Use of artificial nest boxes by two species of small, arboreal mammals in Ecuadorian tropical dry forest

We record, for the first time, the nest structure of two species of small, non-volant mammals, <i>Marmosa simonsi</i> and <i>Rhipidomys latinamus</i>, inside artificial nest boxes in a dry forest ecosystem of Western Ecuador. We describe the nests and categorized them as rearing nest, permanent resting nest and transient refuge, depending on their intended use. Artificial nest boxes provide an optimal place for pup rearing and resting for small mammals, and they can be useful for ecological studies of elusive, poorly-known mammalian species.