What are the characteristics of the species?

• Species of the genus Thomasomys cover a considerable range of size (body length 80-238 mm, tail length 85-329 mm) and weight (mass 14-335 g). The feet are usually narrow, short or relatively long (foot length 13-59 mm). The ears are small or medium and without hair (ear length 12-33 mm). The tail is thin and generally longer than the body. The dorsal and ventral coat is generally dense, soft and long. The dorsal coloration is varied from an olive gray, orange, yellowish brown, reddish brown and grayish brown to almost black forms. The ventral parts are generally paler than the back. The tail is naked or finely hirsute, in some cases with a small brush on the tip. The color of the tail is uniform and often with a white tip.

• Thomasomys species inhabit mainly montane forest habitats. Thomasomys kalinowskii in particular is preferably between 2,000-3,500 meters above sea level. It is found in primary forests of montane and Andean forests and less frequently in disturbed or transitional forests and in cultivated areas.

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Where do we study the species?

• We studied T. kalinowskii and the community of small mammals in the tropical montane forest of the Apurímac river basin (ELU 1), near the community of Chiquintirca, Peru.

• What questions do we seek to answer with the study?

• What is the diversity of species of small terrestrial and arboreal mammals in the montane forest of the Apurímac river valley in the PERU LNG gas pipeline area?

• What is the abundance and richness of rodent species in control (far from the pipeline) and impacted plots (near the gas pipeline)?

• What is the natural history of the rodent community, with emphasis on Thomasomys kalinowskii, including its times of reproduction, population status and diet?

• What are the contributions to regeneration processes of the montane forest that these rodents can have when dispersing seeds and mycorrhizas?

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What general results have we obtained to date?

• Seven species of rodents were found in the montane forest, including three endemic species, Thomasomys kalinowskii (mountain mouse of Kalinowski), Akodon torques (mountain forest mouse), and Calomys sorellus (reddish afternoon mouse). Also reported are Microryzomys minutus (forest rice bug), Oligoryzomys andinus (Andean rice mouse), Thomasomys aureus (golden mountain mouse), Thomasomys oreas (small golden mountain mouse). The species observed include those that are specialists in montane forest habitat and others that are found in open or disturbed habitats.

• In addition, we found four species of marsupials: Didelphis pernigra (white-eared opossum opossum), Gracilinanua aceramarcae, Marmosa and Marmosops impavidus (pale marsupial weasel of Tshudi).

• The diversity of rodents was higher in impact zones than in control areas. This indicates a greater presence of generalist species, or species that can adapt to different conditions in the intervened zones. It was observed that the rodents specialists of the genus Thomasomys, do not use or cross the right of way (RoW) of the gas pipeline. This is being remedied through the revegetation of the RoW.

• In the non-intervened areas we find the normal complement of species, including specialists of the genus Thomasomys, indicating that in general and from the perspective of small mammals, the montane forest of Chiquintirca is still in good condition.

• The diet of the rodent community is quite diverse. We found that many species of rodents can be seed dispersers. There is a high frequency of viable seeds in the feces of Thomasomy kalinowskii, T. oreas, Calomys sorellus, and even in the generally insectivorous Akodon torques. We also found that rodents are consuming mycorrhiza spores, which are small fungi that live in association with the roots of montane forest trees such as the Polylepis pauta, to those that help them obtain nutrients such as phosphorus. These associations serve as the basis to establish guidelines for the conservation of the montane forest.

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Why is the conservation of this species important?

• According to Supreme Decree No. 034-2004-AG of Peruvian legislation and the Red List of the International Union for the Conservation of Nature, T. kalinowskii is in the category of vulnerable, as it is in an area of ​​less than 20,000 km2 and in less than 10 localities, with a continuous decrease in the extension and quality of its habitat.

• T. kalinowskii, in addition to other species studied in the present project, consume seeds and mycorrhizae and disperse them in the forest. Therefore, these rodents are key species for the regeneration of many species of montane forest plants.