I think it is very intentional. There are several migratory species
that fly at very high altitudes. I myself have seen cormorants at over
12'000ft. I've heard of swans flying close to 30'000 ft. Thankfully not
all are as unfortunate as the official record holder:

From http://www.shawcreekbirdsupply.com/world-records.htm

Highest Flying Bird
The highest altitude recorded for a bird is 37,000 ft., for a
Ruppell's vulture (Gyps rueppellii), which collided with a commercial
aircraft over Abidjan, Côte d'Ivoire, on November 29, 1973.

Regards
Marcel



Donn Johnstone schrieb:

...
Canada Goose at 18000 ft, that is impressive, you have
to wonder if that was intentional, on the part of the
goose that is. I know birds go to those heights but
a goose?