captive hyacinth macaws. Reported sightings of tool use in wild parrots go as far back as 1863. Examples of tool use that have been observed usually involve a chewed leaf or pieces of wood. Macaws often incorporate these items when feeding on harder nuts. Their use allows the nuts the macaws eat to remain in position (prevent slipping) while they gnaw into it. It is not known whether this is learned social behavior or an innate trait, but observation on captive macaws shows that hand-raised macaws exhibit this behavior, as well. Comparisons show that older macaws were able to open seeds more efficiently. Reproduction Nesting takes place between July and December, with nests constructed in tree cavities or cliff faces depending on the habitat. In the Pantanal region, 90% of nests are constructed in the manduvi tree (Sterculia apetala). The hyacinth macaw depends on the toucan for its livelihood. The toucan contributes largely to seed dispersal of the manduvi tree that the macaw needs for reproduction. However, the toucan is responsible for dispersing 83 % of the seeds of Sterculia apetala, but also consumes 53% of eggs preyed. Hollows of sufficient size are only found in trees around 60 years of age or older, and competition is fierce. Existing holes are enlarged and then partially filled with wood chips. The clutch size is one or two eggs, although usually only one fledgling survives as the second egg hatches several days after the first, and the smaller fledgling cannot compete with the firstborn for food. A possible explanation for this behaviour is what is called the insurance hypothesis. The macaw lays more eggs than can be normally fledged to compensate for earlier eggs that failed to hatch or firstborn chicks that did not survive. The incubation period lasts about a month, and the male tends to his mate whilst she incubates the eggs. The chicks leave the nest, or fledge, around 110 days of age, and remain dependent on their parents until six months of age. They are mature and begin breeding at seven years of age. General traits Hyacinth macaws are the longest psittacine. They are also very even-tempered and can be calmer than other macaws, being known as "gentle giants". An attending veterinarian must be aware of specific nutritional needs and pharmacologic sensitivities when dealing with them. Possibly due to genetic factors or captive rearing limitations, this species can