my %hash;

{
    my %attribseen;
    while (<DATA>) {
        chomp;
        my ($k, $v) = split /\s/;
        push @{$hash{$k}}, $v unless $attribseen{"$k|$v"}++;
    }
}

print Dumper \%hash;

__DATA__
bird beak
bird beak
bird claw
bird wings
bird feathers
snake fangs
snake scales
snake fangs
snake tail