Little birds don't eat large fruit. Birds really enjoy weed and wildflower seeds. Have fruit that ripens throughout the year. Not every plant produces the same amount of food every year. However, the Florida privet doesn't produce nearly as many berries so a grouping of three or more may be needed in order to provide adequate berries for the birds.
Oaks have a heavy crop of acorns, but only about every fourth year.
Another consideration is the age at which your plants will produce fruit. Conversely, an oak will take 8 to 10 years to produce acorns. Birds usually devour the sweet fruits first, and save the bitter or plain tasting fruit for when there is little else to eat. Beauty berry, Sparkleberry, and gallberry don't have much flavor, but are very important late winter foods. You need to plant at least five individual plants to raise your odds of getting at least two females for fruit production.