Geophagy at mineral licks is common among wildlife in western Amazonia and is widely interpreted as a behavioural response to chronic sodium deficiency. We conducted the first controlled field experiment on sodium attraction, comparing wildlife visitation at paired salt-enriched and untreated control pits. Five pit pairs were monitored with camera traps over six months at Los Amigos Biological Station, southeastern Peru, alongside two natural mineral licks used as ecological references. Mixed-effects modelling revealed a strong system-wide effect of salt supplementation, corresponding to an approximate twofold increase in visitation relative to control pits. Although estimated effect sizes varied among taxa, support for strong species-specific heterogeneity was limited. Responses were nevertheless broadly consistent across terrestrial herbivores, including rodent and ungulate taxa, with the strongest effects observed in paca (Cuniculus paca), brocket deer (Mazama americana and Passalites nemorivagus), and tapir (Tapirus terrestris). Variation in response strength likely reflects both physiological demand and encounter rates, with larger-bodied species having greater sodium requirements and locally common species more likely to detect these artificial salt licks. Patterns of use at artificial salt licks closely mirrored those observed at natural mineral licks for terrestrial species. Most arboreal mammals, however, were absent from artificial salt licks, suggesting that longer time periods may be required for arboreal taxa to detect and incorporate these sites into their foraging behaviour.