On the rare instances when a Vecker egg attaches to a Treelar the egg ends up turning into a Festivecker egg.
Due to the influence of Treelar DNA the Vecker's parasitic nature becomes more symbiotic in the Festivecker. A Festivecker gains its nutrients from other plantlife but instead of draining and killing the other plants it gives back a special nutrient of its own, causing plants and trees that a Festivecker feeds from to flourish and grow even in off-seasons. This growth means that a Festivecker can safely feed off plants without killing them. This also has the side benefit of helping other animals in the area who depend on those same trees and plants. To show their gratitude for the bounty these creatures will gift Festiveckers small baubles or other items. During the winter months small patches of Ark's forests will continue to bloom and grow despite the cold temperatures. These groves are where Festiveckers can be found.