Watched a doumentry once that said Hooper Swans fly at heights of 20k, thought I had misheard, but it was repeated.
According to guinness book of records
Egypian Geese, were photographed crossing the suns disc at 58,080 feet, but this was unverified,{sounds a bit much that} the highest accepted record is 26902 feet by Alpine Choughs.
[ 26 July 2001: Message edited by: tony draper ]