Macaws generally don't hybridise in the wild but will do so in captivity.
Catalina Macaw: hybrid between a Blue and Gold/(Yellow) Macaw and a Scarlet Macaw.
Harlequin Macaw: hybrid between a Blue and Gold Macaw and a Greenwing Macaw.
Ruby Macaw: hybrid between a Scarlet Macaw and a Greenwing Macaw.