Itachi was wary about using his crows, which were mainly used for his ANBU work, in the village, but a clone would serve as well. He could always put a henge on the bird so it would look like a pigeon or sparrow...or use a genjutsu as an initial test, perhaps?

"Ah, but that treads on thin political grounds when all the villages have come together to test their new recruits in a show of solidarity. It's unlikely the children would talk enough about the enemies that attacked them in the maze to make anyone notice, but perhaps it would be safer to stick to unidentifiable attackers with techniques from their common enemies, or Konoha-nin. They'll be expecting Konoha, as they're taking the test here." He should watch them for a while before springing his trap. Surely he could get an idea on what would be the best choice and genjutsu after a while. They were just genin. How much would they be able to hide when they were nervous?