Delimitation of regional management units for desert bighorn sheep in Baja California. An application of the potential species distribution model

Abstract

Models of potential geographic distribution of species are tools for making decisions about the management of wildlife populations, especially species that occupy large areas, such as bighorn sheep.  In the present study, a potential geographic distribution model was generated that can be used for the management of bighorn sheep in the state of Baja California, Mexico.  The model was generated with the maximum entropy algorithm to estimate the geographic distribution area of ​​the species.  The variables used as predictors were climate, relief and vegetation. Meanwhile, the known sites where the bighorn sheep were recorded were obtained from aerial counts carried out in Sierra Juarez in 2012, and at the regional level in 2021, by Romero et al. (2024).  Likewise, records of terrestrial observations reported by Ruiz et al. (2023) were included in Sierra Juarez in 2016; in the Sierra la Asamblea and in Calamajué in 2021; and in Sierra Santa Isabel and Sierra Juarez in 2022.  As well as, the Global Biodiversity Information System. The geographic distribution model revealed that the species in the state of Baja California is distributed along the mountain range of the Gulf of California, in an approximate area of 317,160 ha.  The variables that contributed most to the construction of the model were roughness, type of vegetation and precipitation in the coldest quarter.  The geographic distribution model was used to define 11 regional management units for the species.  Each is shared between two or more agrarian communities.  In Baja California, the management of bighorn sheep must be carried out through community monitoring, habitat protection and sustainable use programs in which the participation of all rural communities that own land within the distribution area of this species is considered.