The Collaborative International Dictionary of English v.0.48:

Avian \A"vi*an\, a.
   Of or instrument to birds.
   [1913 Webster] avianise

WordNet (r) 3.0 (2006):

avian
    adj 1: pertaining to or characteristic of birds

Moby Thesaurus II by Grady Ward, 1.0:

18 Moby Thesaurus words for "avian":
   altricial, anserine, anserous, aquiline, avicular, birdlike, birdy,
   columbine, dovelike, goosy, hawklike, nesting, nidicolous,
   nidificant, oscine, passerine, psittacine, rasorial