What is the highest altitude birds are known to fly?

[strake]

I ask the question as, probably missed by most in yesterdays brew-ha-ha about the Jetstar Airbus, there was another "Airbus window" incident in Russia which was reported on the BBC etc but not so widely. My son happened to be on board.
The Aeroflot A320 was about 2 hours into a flight from Irkutsk to Moscow when there was a "thump" followed by a definite change in pressure in the cabin but no mask deployment. The aircraft made a "smart" descent to what was advised as just under 3000 metres and held for an hour or so. Following this, the aircraft diverted and landed normally at Novosibirsk.
The flight crew stated to the passengers that the aircraft had suffered a birdstrike. Upon landing my son was able to look up at the flight deck windows and saw that they were obviously damaged. He also noticed two distinct depressions under the window.
Now, two hours into the flight, I would expect the a/c to be at least 30,000ft. So, high altitude bird or something else?
PS, if you feel a need to say "wait for the report", then you don't really understand Russian culture ;)

[ampclamp]

Some have been known to fly very high but you'd have to be very unlucky but not as unlucky as the bird.
Bar headed geese migrate over the Himalaya inc Everest.
A species of vulture have reportedly been hit well over 30,000 ft.
Amazing creatures.

[treadigraph]

In the past I have seen several references to large birds being seen by crew at up at 30,000 or so, presumably they may climb that high for migratory reasons and use thermals to get there.

[BOAC]

The last thread I can find of many here (http://www.pprune.org/tech-log/347095-high-level-bird-strike.html)

[bizchaser]

On a recent holiday in Switzerland I visited the Jungfraujoch Mountain which is the best part of 13000ft and observed crows flying around the observatory at that altitude