  We consider the von Neumann and R\'enyi entropies of the one dimensional
quarter-filled Hubbard model. We observe that for periodic boundary conditions
the entropies exhibit an unexpected dependence on system size: for L=4 mod 8
the results are in agreement with expectations based on conformal field theory,
while for L=0 mod 8 additional contributions arise. We explain this observation
in terms of a shell-filling effect, and develop a conformal field theory
approach to calculate the extra term in the entropies. Similar shell filling
effects in entanglement entropies are expected to be present in higher
dimensions and for other multicomponent systems.
