The Humboldt marten (Martes caurina humboldtensis) is a species of conservation concern in northern California and Oregon. Historically, these populations were threatened by unregulated fur trapping and timber harvest leading to a 90% decline in their distribution. Contemporary populations are small and isolated and continue to be threatened by a loss of habitat from timber harvest and increased wildfire risk. Due to their small body size, martens are also at risk of interspecific competition and intraguild predation. Despite efforts to better understand their contemporary distribution and habitat associations, little is known about the abundance and interspecific relationships of Humboldt martens across their current range. To fill these information gaps, we deployed non-invasive hair snares and remote cameras across three sampling grids in the North Coastal California EPA. We developed a spatial capture recapture model to estimate marten abundance and density, and two single-species occupancy models to estimate the space use of fishers and bobcats. We then tested the effects of habitat and carnivore space use on marten density. Given that this is the first effort to evaluate how biotic and abiotic variables influence the distribution and variation of marten density, we offer insights for management and future survey efforts.