This article verifies that the ideal free distribution (IFD)
is evolutionarily stable, provided the payoff in each patch decreases
with an increasing number of individuals. General frequency-dependent
models of migratory dynamics that differ in the degree of animal
omniscience are then developed. These models do not exclude migration
at the IFD where balanced dispersal emerges. It is shown
that the population distribution converges to the IFD even when
animals are nonideal (i.e., they do not know the quality of all
patches). In particular, the IFD emerges when animals never migrate
from patches with a higher payoff to patches with a lower payoff
and when some animals always migrate to the best patch. It is shown
that some random migration does not necessarily lead to undermatching,
provided migration occurs at the IFD. The effect of population
dynamics on the IFD (and vice versa) is analyzed. Without
any migration, it is shown that population dynamics alone drive the
population distribution to the IFD. If animal migration tends (for
each fixed population size) to the IFD, then the combined migration population
dynamics evolve to the population IFD independent of
the two timescales (i.e., behavioral vs. population).