Most research on L1 acquisition of tone focuses on East Asian languages, which are typologically distinct from tone systems in other parts of the world, such as Africa. One important difference is the greater prevalence of grammatical tone in African tone systems. This paper reports on a collaborative longitudinal study of the acquisition of Seenku (Mande, Burkina Faso), with a focus on the methodology for building a naturalistic, longitudinal and cross-sectional corpus, at a distance through community collaboration. While analysis of the tonal patterns is ongoing, preliminary findings corroborate the conclusion that tone is acquired early, with the novel finding that this may extend to grammatical tone.