Many birds are very picky, my parakeets were crazy about a certain grass I picked from outside for them called Chickweed. The pellets have different amounts of different things, for example the ratio is different for protien and fruit and such in the pellet. It shouldn't be so dramatically different that it would harm the bird, but I would stick to just crushing up the bigger pellets. It's good that you have it on pellets though! Some never like the switch from seeds to pellets even though its better for them!