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The distribution and abundance of pumas Puma concolorwithin 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/km2vs 703.3± 296.1/km2) and collared peccary Tayassu tajacu(5.0 ± 2.8/km2vs 146.7± 70.1/km2) faecal groups than Sierra Rica. Conversely, anthropogenic factors such as road density (52.4 km/100 km2vs 43.9 km/100km2), town density (25 towns/100 km2vs 6 towns/100 km2) and human density (6 individuals/100 km2vs 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.

Pumas Puma concolorare stalking predators of large ungulates that usually cache their prey. We hypothesize that they require specific habitats to successfully stalk their prey and that they select cache sites based on some set of criteria. We tested these predictions during a study of predation by pumas on mule deer Odocoileus hemionusin south-central Idaho and northwestern Utah, USA. We found cache points of puma-killed deer in winter by locating radio-collared pumas. We then located where pumas had killed deer (kill points) by tracks in the snow. We classified these kill points relative to the dominant forest type and association with open, edge or forested areas. At a subset of the kill points and associated cache points, we also estimated tree and shrub density, tree diameter at breast height (dbh), shrub height and slope. Pumas killed deer more often than expected (P < 0.001) in juniper-pinyon habitat and in edge areas. Tree densities and dbh at cache points were significantly greater (P < 0.001) than at kill points or surrounding areas. We concluded that pumas relied on specific habitat characteristics to kill mule deer, and selected cache sites with older, larger trees.