**5. Relevance to mammalogy**

Owl pellets can be an effective alternative for measuring small mammal community composition over large geographic areas due to the relative ease and low cost of field collections [6]. Since it is a noninvasive indirect tool, it allows the collection of valuable osteological information. In Ecuador, analysis of pellets has allowed the recording of rare and difficult-to-collect mammal species like *Ichthyomys hydrobates* found in western Ecuador 26 years after the last documented record [15]. Pellet contents have also provided an approximation of the species richness of small mammals in areas with no previous information. For example, we have the first data on presence and abundance of native rodents in previously unstudied Ecuadorian localities in the Andes [49] and western lowlands [15].

Monitoring invasive species (*M. musculus*, *Rattus rattus*, *R. novergicus*) by means of pellets could be a mid- and long-term strategy. They are now known to be agricultural pests because they devastate crops, damage the soil, or eat stored agricultural products [55]. They are also a public health problem because contaminate human food with their excrement [56]. Further, they have a severe impact on several endemic and native species preying on or competing for sources [57]. *Rattus* has caused the extinction of birds on islands, as well as reptiles, small mammals, amphibians, invertebrates, and plants [58]. They are a latent threat to the human species, due to the number of viruses and bacteria they can transmit in their feces, urine, or by direct contact through bites [58].
