Origin of "the bird"

I'm a huge fan of the hallowed American tradition of raising the middle finger to those individuals (and there are so many of them) who have wronged us in some way.

This valuable and eminently necessary gesture has at some point gained the nickname "the bird," which is both indescribably charming and extremely inscrutable, as nothing about it would seem to suggest birds in any way.

How did this indispensable gesture come to be associated with our avian friends, who would seem to have nothing to do with the concept? OED and Merriam-Webster are no help. This question from six years ago, which purports to answer the question, is singularly unsatisfying. Please help.

Solution 1:

I still don't understand "why" the middle finger is called the bird in English... Oh, wait. Maybe it's a direct translation of an Italian expression? After all, “Between 1900 and 1915, 3 million Italians immigrated to America”

In Italian, the colloquial, and rude word for penis is "uccello" which means bird.

From Late Latin aucellus, contracted form of Vulgar Latin *avicellus, diminutive of Latin avis, from Proto-Italic *awis, from Proto-Indo-European *h₂éwis. Compare French oiseau, Catalan ocell, Occitan aucèl, Neapolitan auciello, Sicilian aceddu, Friulian uciel, Venetian oxeło, Ligurian öxéllo, Romansch utschè.

In some Spanish dialects, a penis is commonly called a pájaro (bird), and in Catalan, the term polla (young chicken) is used.

The slang meaning of bird is also used in several Asian languages

bird
A calque from various Asian languages that use "bird" as a slang term for "penis", including Malay burung, Chinese 鳥, and Tagalog ibon.

• (Asian slang) A penis.
  _Wiktionary

Of significant relevance is the English and vulgar term for penis, cock, the "male of the domestic fowl" and not originally the shortened form of cockerel. Since the 1610s, the term cock has referred to the penis in the English language.

The male of the domestic fowl (along with the bull) has been associated in many lands since ancient times with male vigor and especially the membrum virile, but the exact connection is not clear (the cock actually has no penis) unless it be his role as fertilizer of the domestic hens, and there may be some influence from cock (n.2) in the "tap" sense.

Many thanks to @user10518 who posted the following excerpt in the comments below.

• Linguist Jesse Sheidlower traces the gesture's development in the United States to the 1890s. According to anthropologist Desmond Morris, the gesture probably came to the United States via Italian immigrants.
• The first documented appearance of the finger in the United States was in 1886, when Old Hoss Radbourn, a baseball pitcher for the Boston Beaneaters, was photographed giving it to a member of their rival the New York Giants.
  _Wikipedia