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
Foro (bird) proposed that the hoatzin belongs to a highly distinct clade of (probably) Cretaceous origin, the Metaves. As nothing certain about the evolutionary history of the hoatzin lineage throughout the Paleogene is known at all, "F. panarium" cannot support or contradict this hypothesis either. What can be said is that "Foro", with its stocky body and rather weak flight apparatus was in all likelihood a bird that did not fly vast distances. Consequently, it is not very likely that it is congeneric with "Hoatzi", as North and South America were still separate by some of shallow seas and the Central American