I believe you're conflating two different Keith Laumer space operas. The bulb-sorting is from Laumer's Galactic Odyssey, identified in John Thompson's answer. However, the tightrope walking is from Earthblood by Keith Laumer and Rosel George Brown, which was also the answer to this question. Earthblood was originally published as a four-part serial in If, which is available at the Internet Archive (,,,). In part 1 the hero, Roan, is caught using his wire-walking talent to sneak into the circus without paying. The being who interviews him is not an avian, but this must be the scene you're remembering:
The being behind the big, scarred, black-brown desk blinked large brown eyes at him from points eight inches apart in a head the size of a washtub mounted on a body like a hundred gallon bag of water. Immense hands with too many fingers reached for a box, extracted a thick brown cigar, peeled it carefully, thrust it into a gaping mouth that opened unexpectedly just above the brown eyes.
"Some kind of Terry, aren't you?" a bass voice said from somewhere near the floor.
Roan swallowed. "Terry stock," he said, trying to sound as though he were proud of it. "Genuine Terrestrial strain," he added.
The big head waggled. "I saw you on the wire. Never saw a Terry walk a wire like that before." The voice seemed to come from under the desk. Roan peered, caught a glimpse of coiled purplish tentacles. He looked up to catch a brown eye upon him; the other was rolled toward the gilled creature.
"You shouldn't have hurt Ithc." The wandering eye turned back to Roan. "Take off your tunic."
"I want to see what kind of wings you've got."
"I don't have any wings," Roan said, sounding as though he didn't care. "Terries don't have wings; not real original stock, anyway."
"Let's see your hands."
"He's holding them."
"Let him go, Ithc." The brown eyes looked at Roan's hands as he opened and closed them to get the blood going again.
"The feet," the basso voice said. Roan kicked off a shoe and put a foot up on the desk. He wriggled his toes, then put his foot back on the floor.
"You walked the wire with those feet?"
Roan didn't answer.
"What were you doing up there?"
"I was getting in without a ticket," Roan said. "I almost made it, too."