Аннотация:Killer whale families have dialects – unique repertoires of stereotyped calls. Dialects are socially learned and slowly change in time as families diverge and their social bonds fade. To some extent, dialect similarity can be used a proxy of relatedness. In this study we compared the dialects of five resident (fish-eating) communities from the North Pacific: three from the eastern (Southern Residents, Northern Residents and Alaskan Residents) and two from the western (Kamchatka Residents and Commander Residents) North Pacific. To determine the similarity between the repertoires, we used two methods: categorization by the independent observer and dynamic time warping. We used two calls from each type/subtype from each community. The independent observer categorized the pooled samples into the structural categories without the prior knowledge about their community affiliation. Using the dynamic time warping, we compared the similarity of calls from all communities and classified the calls with the similarity >70% as a same call type. After that, we calculated the similarity between the communities based on the number of shared calls using Dice's similarity coefficient. We found that the calls of Kamchatkan and Commander killer whales were more similar to each other, than calls of any of the three eastern North Pacific communities. This finding is consistent with the fact that there is a small exchange between the communities in the western North Pacific: the killer whales from the Kamchatkan community sometimes visit the Commander Islands and socialize with the local whales, and vice versa. In the eastern North Pacific, despite some area overlap between the three communities, no social contact has been registered between them, which can explain the higher level of divergence between their repertoires.