  We study collective dynamics of interacting deformable self-propelled
particles whose migration velocity increases when the local density of
particles is increased. Numerical simulations in two dimensions reveal that
traveling bands similar to those found previously in the Vicsek-type model is
easily formed by this local density dependence of the migration velocity. We
show that a pair of stripe bands which are traveling to the opposite directions
is not destructed by a head-on collision but survives again after collision.
