Scarlet Macaw

Many rainforest seeds and unripe fruits contain chemicals that can harm a bird’s gut, so one popular idea held that parrots eat clay to neutralize toxins. A 13-year study of more than 20,000 hours at a clay lick in Peru’s Tambopata region found no evidence for that. Instead, the clay appears to supply sodium, a mineral scarce in moist tropical forests: it contained about 40 times more sodium than the parrots’ plant foods, and birds ate it mainly for that mineral. Birds even ate clay more often when food was plentiful. Clay eating peaked during the breeding season in all nine species studied, especially while parents were feeding hatchlings, when females face extra nutritional stress. The study is correlational, so researchers plan controlled experiments with captive birds.

Scarlet macaws nest in large tree cavities in the upper rainforest canopy, keeping eggs and chicks high above the ground. Adults measure about 84 to 89 cm (33 to 35 in), more than half of it tail. A female typically lays two to four white eggs and does most of the incubating, which takes about 24 to 26 days, although one source says about five weeks. Chicks fledge roughly 90 to 105 days after hatching, and parents do not start another clutch until the previous young are independent. Nest predators include snakes, monkeys, toucans, and small carnivores, while adults and fledglings can fall prey to jaguars, eagles, and hawks. Adults are less vulnerable because of their size and flight. Poaching and habitat loss are major threats to the species.

Scarlet macaws are strong fliers, reaching speeds of up to about 56 km/h (35 mph) according to several zoo sources, with a wingspan of roughly 112 to 120 cm (44 to 47 in) listed by one. They travel between roosts, feeding trees, and clay licks, and they stay in contact with loud, harsh screeches, guttural squawks, and growls. At clay licks, flocks often burst into the air all at once. One study at a Peruvian lick recorded more than 1,000 such disturbances, and about 90 percent had no apparent cause. Known causes included rockslides, raptors, other large birds, and passing people or boats. The birds usually returned almost immediately, and flocks can abandon a landing if they detect predators or landslides. More than 99 percent of lick use was in groups.

Scarlet macaws are monogamous, and pair bonds last for life. A typical sighting is of a single bird or a pair flying above the forest canopy, and birds are mostly seen in pairs. The female does most of the incubating, and parents do not start another clutch until their previous young are independent, so a pair does not necessarily breed every year. Sexual maturity arrives at about three to five years, depending on the source. Scarlet macaws are commonly cited as living 40 to 50 years, with up to 75 recorded in human care, so a single pair can in principle spend decades together, raising one family after another. Threats such as poaching, trapping, and habitat loss make a long life in the wild far from guaranteed.

By day, scarlet macaws are mostly seen alone or in pairs, though flocks are reported in some areas, and one source says they can reach up to 30 birds. Another describes gatherings of several hundred in places. Young macaws leave their parents about a year after fledging, although another source says they may stay for one to two years, keeping the family together long after the chicks can fly. As evening falls, macaws gather in flocks to sleep, roosting communally in tall trees. They stay in contact with a variety of calls, including loud screeches, squawks, and growls, and in Costa Rica they spend nearly all their time high in the canopy, usually more than 10 m (33 ft) above the ground.

At a clay lick in Peru’s Tambopata region, researchers counted roughly 951 birds arriving each morning, from 13 parrot species. Large macaws began arriving about nine minutes before sunrise, though macaw-only groups formed about 50 minutes after sunrise, and a lick might hold only about 17 large macaws at a time. Large parrot groups, which averaged about 192 birds at their daily maximum, flew slow circles in front of the lick for about three minutes, recruiting birds from nearby trees. Parakeets, by contrast, moved deliberately through nearby trees before flying straight to the lick. Large macaw groups stayed on the clay about 19 minutes, compared with about an hour for large parrots. Macaws sometimes waited near the lick for up to three hours before a group began using it.