Resumo

GALLO-REYNOSO, Juan Pablo et al. Identity and distribution of the Nearctic otter (Lontra canadensis) at the Río Conchos Basin, Chihuahua, Mexico. Therya [online]. 2019, vol.10, n.3, pp.243-253.  Epub 09-Set-2020. ISSN 2007-3364.  https://doi.org/10.12933/therya-19-894.

We have identified a scarcely known river otter population from the Upper Río Conchos basin, northern Mexico, finding a well-established population of the Nearctic otter Lontra canadensis. A pioneer study of these otters at Río San Pedro, a tributary of the Río Conchos, described them as Neotropical otters, Lontra longicaudis; at that time, no specimens or photographs of these otters were available from the locality. Therefore, its taxonomic status remained unclear for various decades. Río Conchos is one of the major tributaries of Río Grande (Río Bravo in Mexico) and its headwaters are located high in the Sierra Madre Occidental. A juvenile otter fur obtained from Río San Pedro was compared to two furs of Neotropical otters from Oaxaca and Sonora, with the aim to compare the structure of primary hairs (PH) and secondary hairs (SH) in order to know their specific status. Camera traps were set-up at Río San Pedro in Chihuahua and in Arroyo Bamochi (occupied by L. longicaudis) in Sonora in 2015 to compare individuals, population structure and occupation in both places. Two other places were surveyed to confirm the presence of river otters: Río Conchos and Río Santa Isabel. Based on hair characteristics (primary and secondary hairs from the juvenile) and photographic evidence from camera-traps, we confirm that otters from Río San Pedro, belong to the Nearctic otter, Lontra canadensis. And presumably in other localities visited in the Concho’s river basin that also has presence of otters, such as Río Santa Isabel and Río Conchos. The population structure from Arroyo Bamochi and Río San Pedro were similar in both areas, but the density of otters is higher at Arroyo Bamochi than at Río San Pedro, even though there is no significant difference between the two sites. Specimens of river otters from Río Grande basin have been identified as L. canadensis lataxina, Cuvier, 1823. The former distribution area of this species ranges from inland US across the Río Grande basin in the Rocky Mountains, the Río Pecos, further East, flowing south and southeast into the Gulf of Mexico. The finding reported here represents a major area occupied by this species, and a significant conservation issue for their protection in Mexico, as well as an indicator of the healthy conservation status of the upper Río Conchos.

Palavras-chave : Chihuahua; Lontra canadensis; Mexico; Otter identity; Status.

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