The Inventur und Schätzung der Joseph Haydnischen Kunstsachen of 1809 is preserved in the Musiksammlung of the Österreichische Nationalbibliothek.
One of the items listed therein is a living parrot, which used to call Haydn by his name and could sing the beginning of the national anthem. The parrot was sold for 1415 florins.
This according to “Haydn als Sammler” by Otto Erich Deutsch, an article included in Zum Haydn-Jahr 1959 (Österreichische Musikzeitschrift XIV/5–6 [May–June 1959] pp. 188–194).
Below, perhaps a descendant.
Launched in 2011 by the Haydn Society of North America and based at the Rochester Institute of Technology, Haydn (ISSN 2163-2723) is dedicated to the dissemination of all areas and methodologies of research and performance considerations regarding the music, culture, life, and times of Joseph Haydn and his circle.
Each semiannual issue will include large and small articles, reviews, reactions to previous articles, and other new and pertinent information. The journal’s Web-based format is intended to take full advantage of current and emerging electronic media.
After Haydn’s funeral in Vienna his former employer, Prince Esterházy, obtained permission to have the body exhumed and moved to Eisenstadt. The matter apparently then slipped his mind until, 11 years later, a distinguished visitor remarked to him that it was fitting that he possessed the composer’s remains.
Not wishing to contradict his guest’s assumption, Esterházy quickly arranged for the coffin to be brought to Eisenstadt; but when it was opened for identification, the horrified officials discovered a headless body—only Haydn’s wig remained. Inquiries led to the revelation that two students of phrenology had bribed the gravedigger and stolen the composer’s head a few days after the funeral.
Esterházy was furious, and demanded that the skull be returned, but efforts to claim it were thwarted when the wife of its keeper secreted it in her straw mattress and lay down on top of it, feigning illness. When Esterházy offered a bribe, he was given the skull of an old man, and this was placed in Haydn’s coffin. The composer’s skull was not reunited with his other remains until 1954.
This according to “An incongruous postlude” in Haydn: A creative life in music by Karl and Irene Geiringer (Berkeley: University of California Press, 1968). For more on Haydn’s physiognomy, see this Bibliolore post.
Above, a drawing of the marble tablet—now lost—erected by Haydn’s devoted pupil Sigismund von Neukomm at the composer’s Viennese resting place in 1814 (click to enlarge). The inscription includes Haydn’s favorite quotation from Horace, non omnis moriar, set by Neukomm as a puzzle canon.