Entry on Glaucous Macaw in Dr. Ockens Allgemeine Naturgeschichte für alle Stände. 5th Volume, Page 370 by Dr. Lorenz Ockenfuß. Published in 1835.

This description is taken from Azara and is undoubtedly that of the Glaucous Macaw (Anodorhynchus glaucus) although Dr. Ocken refers to it as Ps. hyacinthinus. This work is interesting for the wealth of anecdotal information it provides on the habitat and habits of macaws in general as well as the comment that blue macaws were not infrequently seen on stands in small menageries in Germany in the 1830s.

The short German text is followed by the website translation into English:

17. Auch den hyacinthblauen (Ps. hyacinthinus)

sieht man jetzt nicht selten (Red: auf Gestellen) vor den Thierbuden. Er wird auch 2 Schuh lang und ist himmelblau, mit grünem Schiller, unten, Flügel und Schwanz stahlblau, Schnabel und Füße schwarz, Augenkreis gelb.

Sie sind nicht häufig in Südamerica, sollen aber von 27. bis 33 Grad Südbreite gehen, namentlich in Paraguay, in Baumlöcher, und noch häufiger in Üferlöcher nisten, welche sie selbst mit dem Schnabel machen. Azara IV, 53.

English translation:

The hyacinth blue macaw is also not infrequently seen nowadays (Ed: on stands) in small menageries. It is also 2 feet long and is sky blue with a green shimmer, the lower parts, wings and tail are steel blue, the bill and feet black, eye ring yellow.

They are not common in South America, but are supposed to occur between the 27th and 33rd parallel, that is in Paraguay. They nest in tree hollows and more frequently in holes in river banks, which they make with their bill. Azara IV, 53.