Community-based monitoring (CBM)– programs that integrate community members and their values into biodiversity and/or natural resource monitoring– is an effective tool for conservation. Wide inequities exist in CBM collaboration, and monitoring abilities may vary between collaborators of different backgrounds. Therefore exploring the demographic composition of CBM collaborators, and how demographics shape individual monitoring efficacy, can help improve both diversity in CBM representation and program outcomes. Yet, few studies have focused on CBM collaborator demographics, especially in low-income countries. We implemented a CBM project co-designed by protected area managers and local community members in the geographically, biologically, and culturally diverse Southern Madagascar. The project involved 27 scientists and 83 community members who collectively generated 69,429 observations of birds, mammals, amphibians and reptiles across two years (2917 surveys). Using linear regressions and mixed-effects models, we examined how collaborators' demographics (gender, age, and level of formal education) and their prior amount of biological monitoring experience impacted their efficacy, measured as the number of observed species. For both scientists and community members, monitoring teams with women, despite being underrepresented, on average observed more species than male-only teams. Among community members, age and level of formal education had smaller positive effects on efficacy. Our results suggest that CBM projects should actively engage a broad array of community members, including those with marginalized identities, to provide diverse perspectives. Inclusive initiatives offer both tangible (lower project costs) and intangible (community engagement, education, and enhanced collaboration) benefits for local communities and conservation managers alike.