Thanks for reaching out to Ask Lafeber. You can simplify your feeding routine by using a single Nutri-Berries size for all of your birds. For your flock—an African Grey, an Umbrella Cockatoo, and two Rose-Breasted Cockatoos—the cockatoo-size Nutri-Berries (larger size) are the best all-around option. This size is ideal for your cockatoos, as their strong beaks are designed to handle larger pieces and benefit from the added enrichment of cracking them apart. Your African Grey should also have no difficulty eating the larger Nutri-Berries and may even enjoy the extra foraging challenge. Additionally, using the larger size can help reduce waste, as bigger birds often crumble smaller berries. If needed, you can break a few pieces in half during the transition, but in general, cockatoo-size Nutri-Berries will work well for your entire flock.