In-Depth Questions on the Parsha and Rashi's commentary. Which procedure of the minchah offering requires a Kohen. The Torah forbids bringing honey with the minchah.
Birds eat food that they scavenge.
Animals, however, eat food provided by their owners. The above implies that dependence on humans is desirable. Violating a negative command which is rectified by a positive command. Therefore, the Torah wants his offering to look nice, and it looks better with feathers. A flour offering fried in a shallow pan.