Migratory routes are inherited primarily from mother in a terrestrial herbivore

For many migratory ungulates, cultural inheritance maintains migration
through social transmission of information between individuals, while
learning and memory inform movement within individuals. It often is
assumed, but rarely tested, that offspring inherit migratory routes by
learning from their mothers. 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 experience 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 life-long 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 life-long 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 resilience of an often-imperiled behavior in a
changing world.