Habitat loss and fragmentation are usually construed as having negative consequences for wildlife, and habitat heterogeneity as having a positive effect. We conducted a mammal survey in eucalypt woodlands near Darwin, and found very few mammals in an intact region of the study area. This is consistent with an emerging pattern suggesting that many mammal species are declining across northern Australia, even though habitats remain relatively intact. However, we also found apparently healthy populations of the same species in a fragmented region of the study area. Using a combination of remote sensing, GIS and generalised linear modeling, we found some evidence of relationships between fire regime, fire heterogeneity or vegetation heterogeneity and the distributions of mammal species in this area. However, there was a strong regional component of the distribution that is not explained by these variables. The cause of the lack of mammals in the intact region of the study area has not been revealed by this analysis. One possible reason for this failure is that the landscape variables used in the analysis were too fine to detect variation in mammal abundance occuring at a much courser regional scale.