ResumenEn la costa y vertiente occidental ocurren los principales endemismos de mamíferos peruanos. Así mismo, a lo largo de la costa central, sobresale el único mamífero endémico del departamento de Lima, el ratón arrozalero de Zúñiga, Melanomys zunigae (Sanborn, 1949), registrado en las lomas de Atocongo y el cerro San Jerónimo por Enrique Zúñiga en 1942. Desde entonces se han realizado esporádicas evaluaciones, no necesariamente dirigidas a su búsqueda, aunque sin ningún registro. Nuestro estudio tuvo como objetivo la búsqueda de evidencias de la presencia de M. zunigae en las lomas de Lima, basados en un trampeo no exhaustivo y posteriormente en un análisis de regurgitos de la lechuza de los arenales (Athene cunicularia). Desafortunadamente no registramos ningún individuo de M. zunigae; sin embargo, encontramos evidencias que el impacto de la expansión urbana estaría afectando los ensamblajes de mamíferos pequeños en las lomas de Lima. Varios factores pudieron haber determinado la desaparición de M. zunigae. Entre estas se incluyen la destrucción del hábitat, invasión de especies exóticas y el aislamiento de las lomas. Palabras clave: Melanomys zunigae, Mamíferos pequeños, Lomas, estado de conservación, Lima, Perú AbstractThe coastline and the western slopes of the Andes are main sites of Peruvian endemic mammals. Along the central coast occurs the only endemic rat from Lima, Zuniga's dark rice rat, Melanomys zunigae (Sanborn, 1949). It was collected by Enrique Zuñiga in 1942 at Lomas de Atocongo and Cerro San Jerónimo. Since then, sporadic searches have been conducted, not necessarily targeted at finding it, but without records. Our study was aimed at finding evidence of its presence in the Loma formations around the city of Lima. Our methods were non-exhaustive trappings and the collection of burrowing owl (Athene cunicularia) pellets. Unfortunately no evidence of the presence of M. zunigae was found. However, we found evidence that the impact of Lima´s urban sprawl would be affecting small mammal assemblages at the Lomas. Several factors could have determined M. zunigae´s disappearance: habitat destruction, exotic species invasions and Lomas isolation.

Tarucas (Hippocamelus antisensis) live in rocky areas in the Andes, from northern Peru to northern Argentina. Microhistological analyses on their feeding ecology during the rainy and dry seasons were done at a National Park and a Landscape Reserve. The diet was diverse and more than 50 species were identified from the feces. Grass species were most often detected as eaten by taruca during the rainy season comprising near 70% of the consumed fragments with 35 plant species identified as eaten then. In the dry season, around 50 species were identified as eaten by tarucas, mostly dicotyledonous. The main species consumed in both seasons wereWerneria nubigena,Poa gymnantha,Senecio comosus, andEphedra americana. The ecological density was an intermediate value compared to other observed values in Peru. This is the first study to find the importance of grasses for tarucas, selected when soft, during the rainy season. A possible overlap with domestic ungulates’ diets should be explored, helping the conservation of taruca and generating an adequate management of the species and the ecosystem. There is a change in the palatable offer of food items during the rainy season, when most of the Gramineae species are tender.