Bird migration evidence. Seabirds fly low over water but gain altitude when crossing land, and the reverse pattern is seen in landbirds. However most bird migration is in the range of . Bird strike aviation records from the United States show most collisions occur below and almost none above . Bird migration is not limited to birds that can fly. Most species of penguin (Spheniscidae) migrate by swimming. These routes can cover over . Dusky grouse "Dendragapus obscurus" perform altitudinal migration mostly by walking. Emus "Dromaius novaehollandiae" in Australia have been observed to undertake long-distance movements on foot during droughts. While participating
Not Only... But Also Bus", being reconstituted from film footage newly recovered from the Australian Broadcasting Company trailer department. "Peter Cook and Dudley Moore: The Missing Sketches", transmitted on New Year's Day 2017, included further ABC trailer extracts from 'Pete and Dud - Diseases' and 'Pete and Dud – Sex'. One remaining recovered clip, lasting one minute and 25 seconds, of 'Pete and Dud – Music' remains unscreened to date. A 1971 visit to Australia for the live show "Behind the Fridge" (the name was a pun on "Beyond the Fringe") saw Cook and Moore record two half-hour "Not Only... But Also" specials for