The Collaborative International Dictionary of English v.0.48:

Migratory \Mi"gra*to*ry\, a. [Cf. F. migratoire.]
   [1913 Webster]
   1. Removing regularly or occasionally from one region or
      climate to another; as, migratory birds.
      [1913 Webster]

   2. Hence, roving; wandering; nomad; as, migratory habits; a
      migratory life.
      [1913 Webster]

   Migratory locust (Zool.) See Locust.

   Migratory thrush (Zool.), the American robin. See Robin.
      [1913 Webster]

WordNet (r) 3.0 (2006):

migratory locust
    n 1: Old World locust that travels in vast swarms stripping
         large areas of vegetation [syn: migratory locust,
         Locusta migratoria]