Classified internationally as Endangered through IUCN,[1] the thick-billed parrot's decline has been central to multiple controversies over wildlife management.

However, recent molecular DNA studies indicate that pachyrhyncha and its sister species terrisi in genus Rhynchopsitta are conspecific subspecies.

[3] Rhynchopsitta is one of numerous genera of New World long-tailed parrots in tribe Arini, which also includes the Central and South American macaws.

The bird was first described by English naturalist and illustrator William Swainson who designated it Macrocercus pachyrhynchus in Philosophical Magazine, new ser., 1, no.

Swainson evidently thought that because of its size and heavy beak, that it was a macaw (at that time, any parrot of the genus Sittace, or Macrocercus).

The voice of the thick-billed parrot resembles a high-pitched macaw and includes a variety of harsh, rolling calls described as similar to human laughter.

Highly social, they may feed each other food stored in their crop (a pouch in the throat), and spend their free time preening each other.

[citation needed] The thick-billed parrot lives in temperate conifer, pine, mature pine-oak and fir forests at elevation of 1200–3600 meters.

Early accounts also place them in far west Texas (with famed ornithologist John James Audubon sighting them in El Paso in 1827), and possibly as far north as Utah.

They deal with deep snow by hanging upside-down and climbing on the bare underside of a snow-covered branch in order to access cones.

[15] A 2004 BirdLife International survey suggested that there may be 2,000–2,800 mature individuals and only 100 active nests in the entire population, but notes that this may be an overestimate; the distribution of this species is only 600 square kilometres (230 sq mi).

Due to extensive human development, residency, agriculture, etc., high numbers of predator species exist, especially the American goshawk.

In October 2020, it was announced that, working with Mexican officials, researchers in Arizona planned to reintroduce the thick-billed parrot to the state.

A representative with the Arizona Game and Fish department stated that the birds' preferred habitat is "high elevation forests like the Chiricahuas.

[10] The lack of a bare facial patch, as is seen in macaw images at the site, is widely considered diagnostic for the identity of the painted bird.

[20] In 2023 the thick-billed parrot was featured on a United States Postal Service Forever stamp as part of the Endangered Species set, based on a photograph from Joel Sartore's Photo Ark.