Migratory routes are inherited primarily from mother in a terrestrial herbivore

For many migratory ungulates, cultural inheritance maintains migration through the social transmission of information between individuals, whereas learning and memory inform movement within individuals.^1,2,3 It is often assumed, but rarely tested, that offspring inherit migratory routes by learning from their mothers.^4,5 Here, we evaluate whether daughters inherit migratory routes from their mothers by following 16 mother-daughter pairs of mule deer (Odocoileus hemionus) from each daughter's first migration, through their yearling migration, and into adulthood. Adult routes for two-thirds of daughters overlapped with their mother's route, suggesting that they inherited migratory routes from their mothers. The adult routes for the remaining daughters, however, bore little or no similarity to their mother's routes, suggesting that these routes were instead shaped by individual experiences or non-maternal social interactions. Regardless of whether routes were inherited or not, the strategy that daughters used was influenced by their yearling migratory route, which underscores the importance of this period for establishing lifelong behaviors. For mule deer and other species where migration is informed by cultural inheritance, learning, and memory, the specific mechanisms that establish memory can have lifelong and cross-generational ramifications. Our work emphasizes the role of social information and early-life experiences in establishing and maintaining migratory behavior, raises new lines of inquiry about what underpins variation in migratory behavior, and points to potential strategies for the resilience of an often-imperiled behavior in a changing world. VIDEO ABSTRACT.