To examine the value of tongue spots as a tool for determining the age-class of Lanceolated (LGW), Middendorff's (MGW), and Sakhalin Grasshopper warblers (SGW), interspecific and individual differences in tongue spots were inspected during the breeding seasons from 2020 to 2023 in Hokkaido. A subjective tongue spot scoring system (TSS) was used. A score of TSS 1 indicates black is very light and barely visible; TSS 2 indicates that the spots have an indistinct outline and are light black; while TSS 3 indicates that spots have clear outlines and are dark black. The tongue spots of a pair of LGW differed, the male was TSS 3 and the female TSS 1. The male TSS 3 was comparable to the most distinct juvenile MGW. Tongue spots in LGW are suitable for age-class determination. Out of 40 adult SGWs, 22.5% were classified as TSS 1, 70% as TSS 2 and 7.5% as TSS 3. Out of 149 adult MGWs, 72.5% were classified as TSS 1, and 27.5% as TSS 2; none were TSS 3. TSS did not change between successive years in SGW or MGW, making it impossible to determine their age classes. A possible significance of tongue spots as a signal of physiological condition was investigated in juvenile MGWs. Of the 41 juvenile MGWs, 12.2% were classified as TSS 1, 48.8% as TSS 2 and 39% as TSS 3. Juveniles with TSS 2 had shorter wings and longer tails than those with TSS 1. This inconsistency means that the process of fading of tongue spots is not simply the result of ageing. There were individual differences in TSS within the same brood in the same nest. We assumed that dark tongue spots of juvenile MGWs were a signal of their good physiological condition.