Next to the airplane, what's the farthest-traveling manmade flying machine?

[smithsb]

@xanthous

I should have provided a little bit of clarity. I was thinking about planes as man’s attempt to “fly like a bird” and I wondered if there was another type of flying craft that can make it as far as, say, a cross-continental migrating bird.

(TriPolar, I think you figured me out.)

@Superhal

Helping with OP:

"Next to the airplane, " = not a fixed wing, engine powered flying machine, including planes and jets. By this definition, I think dirgibles would be eliminated, as they do have fixed wings and engines, although lift is created by gas.
“what’s the farthest-traveling manmade flying machine?” = not natural, like pollen that travels in the earth’s planetary air currents.
“And by farthest-traveling, I mean cross-continental,” = Within the atmosphere, thus eliminating spacecraft.
“as in migrating like a bird.” = Birds stop and “refuel” during migrations. Logically, this would eliminate rockets, regardless of how far that rocket could fly, as nearly anything that could refuel would exceed it over time. However, also logically, this would make the question unanswerable since theoretically you could keep repairing and flying say a hang glider for hundreds of years.

An answer for the birds - yes they do fly long distances without landing or refueling -
FARTHEST FLIER: BAR-TAILED GODWIT
Before they head south for the winter, bar-tailed godwits get so plump, they took like flying softballs. In autumn, the birds fly from Alaska to New Zealand without landing to rest or eat. Scientists tracked one bird that traveled 11,000 kilometers (6,800 miles) nonstop in nine days. That’s the longest nonstop flight for any bird.