Pidgeanhas

Carnivorous pidgeons.
Their beaks devolved into dinosaur-like maws filled with little piranha-like teeth.
Their feets have sharp claws that allow them to cling to the skin, fur or garments of their victims.
They attack in flocks, tageting large animals lacking chitinous or scaly armor.
Flocks are usually composed of 5+3D10 individuals.
They will not attack immediately, the flock will first stand in high places around their target, or fly in circles around it. They do this to assess how dangerous the creature is. They are not afraid of animals or humans in groups. Against them, most of the study goes into determining which member of the group is the weakest, and they will target that one.
This process usually lasts about 3-6 seconds. If during that time the target or its allies manage to kill 1 or 2 pidgeanhas, they will leave. If no pidgeanhas are killed, they whole flock will attack a single weakest target, swarming it beyond any hope, and leaving only the bare bones behind.
When they are studying the prey, they can be targeted using ranged attacks, but once they start the attack, thattacked in dividual may kill a couple, but fightning all of them is usually impossible. If they are attacking an ally of yours, you may kill one, two, and many of your attacks against the swarming flock will also result in damage to your ally.
In many cases, people just throw a molotov at the attacking flock, thus ending the suffering of the poor bastard and getting rid of the whole flock.