We describe observational evidence of niche shifts of smaller species in response to the presence of larger species in flocks of tits in Korea. Overall, in this guild of tits there was more aggression directed from larger toward smaller species than vice versa. At the guild level, there was a significant effect of the presence of larger species on vertical rather than horizontal distribution of smaller species. For example, in the presence of the dominant P. varius, the subordinate P. major foraged at lower heights than in the absence of P. varius. This is the first observation of foraging niche shifts in P. major, a typical dominant in European flocks, in response to the presence of larger P. varius, absent in European flocks of tits.