The relative abundance of Scarlet-thighed Dacnis is uncommon compared to other Neotropical birds (Parker et al. 1996). The population size is unknown, but the trend is thought to be stable (BirdLife International 2017). It perhaps is expanding its range northward into Nicaragua (although it may just have been overlooked there previously). Concurrently it perhaps is declining most strongly at itssouthern limits in Ecuador, with these individuals threatened by deforestation and habitat fragmentation (Granizo et al. 2002). In Costa Rica, analysis of population trends over twenty-three years of Christmas Bird Counts at La Selva Biological Research Station shows stability (Boyle and Sigel 2015). Scarlet-thighed Dacnis is the type host of the chewing louse Myrsidea venustae (Price and Dalgleish 2006).