Evie had slept peacefully the entire night while the vampires took turns to go out and hunt for food. To their relief, there were many non-magical animals roaming around the forest near the dragon's gate. Thus, there was no problem for them in hunting down game to stock up on their food supply.
In the past, the vampires had to bring blood along with them during their journey to the forbidden land because they had found out that there were almost no normal animals around. They had seen orcs and other beasts eating the normal animals, so they knew they had to compete with the beasts to get food.
But by the gate, the animals were quite aplenty. It seems that the dragons were not touching them and that was why they took refuge within this area.