To test the effects of seasonal heterogeneity on a reintroduced carnivore, American martens (Martes americana), we compared metrics of local and season-specific heterogeneity to traditional forest metrics on the survival of 242 individuals across 8 years and predicted a survival landscape for 13 reintroduction sites. We identified a set of variables that characterized potentially important drivers of marten survival, allowing for a comparison between heterogeneity metrics (i.e., complexity of vegetation, land cover, and abiotic conditions) and landscape variables representing composition and configuration. We summarized environmental conditions encountered by individuals by extracting landscape variables and measures of heterogeneity within 95% kernel density estimate. To test the influence of landscape variables and heterogeneity on survival, we modeled mortality risk from time-to-event data using a Bayesian framework.