Their large, strong beaks are capable of cracking tropical nuts, even the super-hard Brazil nut. Large flocks of these birds have been observed eating mud from cliffs that contains a high salt and mineral content. Macaws nest in hollows in trees, sometimes high up from the ground. Males and females pair for several years, many for life. After breeding, the female lays 2 white eggs.
Incubation varies by species but is generally about one month.
During incubation adults are very aggressive whenever their nest is approached. Chicks are born completely naked and blind. At about 4 weeks, the eyes open, the beak darkens, and wing quills begin to appear. By ten weeks the chick is fully fledged, but remains in the nest for another 3-4 weeks. At six months the chicks look just like their parents and are fully grown.