The blue-crowned parakeet, blue-crowned conure, or sharp-tailed conure (Thectocercus acuticaudatus) is a small green Neotropical parrot with a blue head and pale beak native to large parts of South America, from eastern Colombia in the north to northern Argentina in the south. They inhabit savanna-like habitats, woodland and forest margins, but avoid dense humid forest such as the Amazon. This species is officially called a parakeet by the AOU and by birders, though usually called conures in aviculture.
The blue-crowned parakeet is a medium-sized bird measuring approximately 37 cm (14.5 in) in length and weighing between 140 and 190 g (4.9 and 6.7 oz). Blue-crowns are born with red coloring around the head, but blue-crowns are predominantly green, with dull blue coloring on the forehead, crown, cheeks, and ears in the nominate, but less blue in other subspecies. It has a ring of white featherless skin around each eye, though this is bright orange-yellow in wild T. acuticaudata neumanni. The breast feathers may also be tinged with blue, though they are more commonly green to yellow-green. Closed wing coloring matches that of the body while extended wings show blue-brown, becoming chestnut on the outer flight feathers. The tail feathers are green on top, maroon to red-brown on the underside, iridescing to bright orange and scarlet under full-spectrum light. Legs are pink-brown with grey-brown claws. The upper mandible is horn-colored, tapering to a needle-sharp, grey-black tip. In the southern and western nominate and subspecies neumanni, the lower mandible is horn-colored in juveniles, fading to grey-black by the bird's second year. The remaining eastern, central and northern subspecies retain the horn-colored lower mandible throughout adulthood.
The blue-crowned parakeet's nest is a hole in a tree. The eggs are white and there are usually three to four in a clutch. The female incubates the eggs for 26 days, and the chicks fledge from the nest about 52 days after hatching.