The “bird circuit” of gay bars existed in Manhattan, along Third Avenue around the lower East 50s, after World War II. The bars had such names as the Blue Parrot (on East 53rd Street), the Golden Pheasant (on East 48th Street) and the Swan. Police raids eliminated the bars by the late 1960s.
 
“Bird circuit” has been cited in print since at least 1953, when it was mentioned in the Tennessee Williams play Camino Real. The “bird circuit” term is infrequently used to describe a district of gay bars in any city.
 
A person frequenting the gay circuit is called a “circuit queen.”
 
     
Google Books
Camino Real
By Tennessee Williams
New York, NY: New Directions Books
1970 (Originally published 1953)
Pg. 39:
THE BARON:
Oh, the hot spots, ho ho! There’s the Pink Flamingo, the Yellow Pelican, the Blue Heron, and the Prothonotary Warbler! They call it the Bird Circuit. But I don’t care for such places. They stand three-deep at the bar and look at themselves in the mirror and what they see is depressing. One sailor comes in—they faint!
 
14 April 1953, Muncie (IN) Star, “Walter Winchell In New York,” pg. 9, col. 6:
IN THE Tennessee Williams play, “Camino Real,” there is a line referring to “The Bird Circuit.” ... The liquor authorities have discovered “The Bird Circuit” is the nickname for bars and joynts which invite the patronage of the town’s whoopsys….The A.B.C. Board is carefully scrutinizing all hooch licenses issued to places featuring the name of some bird….This does not refer to spots using the word “bird” itself but to places which have peacocks, parrots, swans, pheasants, canaries, etc., in their names….The Stork Club is the top exception. Billingsley bars limp-wristers.
 
17 June 1953, Daily News (New York, NY), “Dream Street” by Robert Sylvester, pg. 64, col. 4:
But the most fantastic change has been the growth of “The Bird Circuit.” This is a series of East Side saloons which cater only to the gay set. On the Bird Circuit it’s Old Homo Week all year long. There is never a gal in a Bird Circuit saloon. Only the birds. They stand at the bar three deep. They never wear hats, possibly because they have just come from the hairdresser. Their shiny blonde tresses are slicked down. The crewcut—“Very Butch,” the birds say—is highly popular. They twitter and they cruise. And they whisper nasty things about each other.
 
Furthermore, only birds are wanted along the Bird Circuit. Not long ago a reasonably normal guy fell into a bird trap for a glass of beer. A little toughie, obviously the owner, came up and told him bluntly that he wouldn’t like the place. He wouldn’t be served. Go somewhere else.
 
14 February 1954, Sunday News (New York, NY), “Bulldozers in Bohemia” by Worth Gatewood, pg. 21C, col. 4:
The tolerant Village long ago acquired a reputation as a haven for homosexuals. Guides on the rubberneck buses acknowledged it by bawling as they passed Sheridan Square: “And now we’re in Greenwich Village. home of short-haired women and long-haired men.” The reputation has stuck to this day, although there probably are fewer members of the Gay Set—as they call themselves—in the Village now than there were a decade ago. Their principal hangouts are in uptown saloons on the “bird circuit.”
         
11 October 1955, Daily News (New York, NY), “Dream Street” by Robert Sylvester,, pg. C16, col. 1:
On Lexington, on Third, and in the side streets between, there now operates what is commonly known as the Bird Circuit. This is a series of saloons which cater exclusively to the homosexual trade.
   
25 July 1971, Sunday News (New York, NY), “Violent Turn,” pg. 93, col. 2:
Among the non-laughers, there was Frankie RIbando, night manager of P. J. Clarke’s.
 
“God knows I do not fault the police,” said Frankie. “But somebody made a big mistake. There was a time in this district when there was a thing called The Bird Circuit. Each of these saloons had a Frenchy type name which represented a bird.  The police closed them down during a previous administration. I wish they hadn’t. Because now all the poor male hustlers are out there on the street.”
 
Google Books
The Gay Metropolis:
The Landmark History of Gay Life in America
By Charles Kaiser
New York, NY: Grove Press
1997
Pg. 106:
There was another famous cluster of gay bars near Third Avenue in the East Fifties known as the Bird Circuit: the Blue Parrot on 53d, the Golden Pheasant on 48th, the Swan and the 316—at 316 East 54th Street.
 
Urban Dictionary
bird circuit
taking a tour of all the local gay bars in an area.
Roger: Hey man, what are you doing tonight?
Philip: I’m going on a bird circuit with Steve.
Roger: Wow dude thats fucked up.
#gay#gay bar#homosexual#queer#fag#homo
by Dr Foreman June 05, 2009
     
A Week in New York in 1946
The East Side Gay Scene in 1946
(...)
A string of gay bars along Third Avenue with ornithological names known to patrons collectively as “the bird circuit” gave rise to the term “circuit queen” which lasted for decades after the bars were gone. Did these bars exist in 1946? I can find no definitive evidence. Perhaps the middle class gay community was more circumspect in the 1940s than Remarque portrayed. Or maybe it is simply that the young gay men of the 1950s East Side, who were only in early middle-age when gay history began to be written in the 1970s, were more willing to share their stories than their elders. This particular segment of the gay world did not talk openly about such things back in their day. 
Posted 22nd January 2011 by Bill Bence
 
May/June 2015, The Gay & Lesbian Review Worldwide, “Before There Was Mapplethorpe” by A;;en Ellenzweig, pg. 30:
Then off into the night the princely Wagstaff would go, frequenting the 1950s Bird Circuit along Third Avenue in the East Fifties “where gay bars with names like the Blue Parrott and the Gold Pheasant were hiding in plain sight.”