Conservation status assessment of bird species is essential to prioritize conservation and monitoring efforts; however, this is not always possible to achieve due to lack of field data or scientific knowledge. In this context citizen science platforms can act as a data source to prioritize the conservation and research resources within a region or a given taxonomic group. Merging the available information on bird distribution areas from BirdLife International and field observations from eBird, the main citizen science birding app, we create a concern index, using the poorly known buttonquails (Turnicidae) as a case study. This concern index is based on two parameters: scarcity and uncertainty, which ultimately are based on two components, respectively. For every species, we defined scarcity as a combination of its frequency of occurrence (proportion of positive eBird checklists) and its relative range size, while uncertainty is a combination of the eBird effort (density of eBird checklists) and the range accuracy (proportion of positive eBird checklists within the BirdLife distribution area). We found a high correlation (Spearman r = 0.74) between our concern index and the IUCN threat categories for all buttonquail species. Then we apply this concern index to all buttonquail subspecies obtaining a ranked list for these non-assessed taxa, with some island endemic subspecies ranking very high together with the most endangered buttonquail species. Our approach is a very simple method to rank species within a given bird group and prioritize monitoring and conservation efforts. Moreover, it is also suitable for other taxonomic levels as subspecies or even for ecological units as populations, which normally lack a formal conservation status assessment.