The majority of the hyacinth macaw diet is nuts, from native palms, such as acuri and bocaiuva palms. They have very strong beaks for eating the kernels of hard nuts and seeds. Their strong beaks are even able to crack coconuts, the large brazil nut pods, and macadamia nuts. The birds also boast dry, smooth tongues with a bone inside them that makes them an effective tool for tapping into fruits. The acuri nut is so hard, the parrots cannot feed on it until it has passed through the digestive system of cattle.[5] In addition, they eat fruits and other vegetable matter. The hyacinth macaw generally eats fruits, nuts, nectar, and various kinds of seeds. Also, they travel for the ripest of foods over a vast area. In the Pantanal, hyacinth macaws feed almost exclusively on the nuts of Acrocomia aculeata and Attalea phalerata palm trees. This behaviour was recorded by the English naturalist Henry Walter Bates in his 1863 book The Naturalist on the River Amazons, where he wrote that