The distribution and abundance of pumas Puma concolor within mountain ranges of similar size in the Mexican Chihuahuan desert is known to vary. In 2001–2002, we tested 11 variables pertaining to habitat composition, prey abundance and anthropogenic factors to identify which ones might explain the difference in puma abundance between two mountain ranges (El Cuervo and Sierra Rica) of similar size. We found that shrub density (32.2±1.9 (SE) vs 30.0±1.7 shrubs/km²) and diversity (2.1±0.1 vs 1.9 ± 0.1) did not differ between the two ranges. However, El Cuervo had significantly lower density of mule deer Odocoileus hemionus (158.3 ± 62.6/km² vs 703.3± 296.1/km²) and collared peccary Tayassu tajacu (5.0 ± 2.8/km² vs 146.7± 70.1/km²) faecal groups than Sierra Rica. Conversely, anthropogenic factors such as road density (52.4 km/100 km² vs 43.9 km/100km²), town density (25 towns/100 km² vs 6 towns/100 km²) and human density (6 individuals/100 km² vs 0.08 individuals/100 km²), were higher for El Cuervo than for Sierra Rica. We hypothesized that anthropogenic factors were the most important in explaining the difference in abundance of pumas between the two ranges. We propose that the higher number of people and accessibility to El Cuervo results in a high incidence of illegal hunting which suppresses prey and puma populations. We discuss the consequences of our results to the conservation of pumas in the Mexican Chihuahuan desert.