Ecological Niche Modeling uses the geographic coordinates of species presence records as the primary input to estimate potential geographic distributions.It is little known whether carrying out rigorous data pre-processing is necessary before building niche models to be transferred to different time period.Here we compared the current,past,and future potential distributions projected by niche models built from two different databases,an open-access database and a database compiled ad hoc,for Handleyomys chapmani,a rodent closely associated with montane cloud forests in Mexico.The models predicted different spatial patterns of climatic suitability for the three periods examined.Based on our current knowledge of cloud forest species in Mexico,the distributions predicted by the model built from the ad hoc database are more ecologically realistic than those obtained from the open-access database.The models built using the open-access database were particularly inaccurate at the limits of the geographic range,predicting larger,more diffuse distributions for the three periods.We conclude that pre-processing occurrence data is crucial for mountain species,as the number of localities and even minor inaccuracies in the geographic coordinates can translate into very different climatic conditions due to abrupt altitudinal changes.Finally,the predicted shifts in the potential distribution of H.chapmani over time indicate that this species is highly susceptible to climate change.