The hawks possessed incredible speed, and with the caravan using the narrow road of the mountain in order to traverse it, they had an advantage as the adventurers and mercenaries could not move as freely as before and had to be incredibly careful during battle.
There were about 14 hawks coming at them. Out of the 14, 4 were Bronze Core hawks and their size and speed were much greater compared to the ones below the Bronze Core realm. Even the Bronze Knights that were masters at long-range combat couldn't easily deal with the four hawks and would need to fully focus on them, leaving the other long-range attackers to deal with the other hawks.
The melee combatants wouldn't be of much help here since the hawks attacked by swooping down, grabbing a person, and then flying up before letting go of their prey and allowing gravity to do its work.
The hawks would have to be dealt with before they were able to get too close.