Many parrots, especially the macaws, are monogamous, and pairs may mate for life. The long relationship is often cemented by regular allogrooming and the sharing of food. Hyacinth macaws are large birds (90 to 100 centimeters in length) weighing more than 1.5 kilograms. Their coloring is a spectacular violet-blue with a bright yellow bare eye-ring and a yellow crescent-shaped lappet next to their lower mandible.