We analyzed the habitat preferences of white-tailed deer in a 1,000 ha area in an and region of northeastern Mexico where drinking water is abundant throughout the year (via 33 water troughs). Seven habitat types in the study area were identified and characterized. Within each habitat, feeding, searching, and bedding activities were evaluated during the reproduction, postreproduction and fawning seasons of the annual deer cycle. The Acacia-Celtis habitat provided the greatest amount of hiding and thermal cover and edible food. The Prosopis habitat also provided significant hiding and thermal cover. Hilaria and Opuntia were the most open habitats. Habitat preferences, evaluated by radiotracking 14 deer over a period of 2 years, varied between sexes and years (P much less than 0.00001), but not among seasons (P > 0.05). Mate deer preferred open habitats, while females preferred more densely covered ones. Males and females avoided Prosopis during 1996. Both sexes distributed the 3 activities more evenly during 1996 than during 1995. In 1995, females preferred Flourensia and Acacia-Celtis habitats for all activities, and during 1996 males preferred Hilaria and Leucophyllum. Between year changes in precipitation could explain the observed variability: during 1995 rainfall was 136 mm, as compared to 276 mm In 1996. Requirements for cover increased markedly in 1995 due to high predation and extremely dry conditions. Overall, our study shows that under good weather conditions, habitat preferences are best explained by variables associated with food availability, while thermal cover is more important under harsh weather conditions, even when drinking water is abundant.