researchers from the universities of Oxford, Barcelona and Pisa have shown in a new experiment that olfaction – or sense of smell – is almost certainly a key factor in long-distance oceanic navigation, eliminating previous misgivings about this hypothesis. . . .although the anosmic birds made successful trips to the Catalan coast and other distant foraging grounds, they showed significantly different orientation behaviour from the controls during the at-sea stage of their return journeys. Instead of being well-oriented towards home when they were out of sight of land, they embarked on curiously straight but poorly oriented flights across the ocean, as if following a compass bearing away from the foraging grounds without being able to update their position.
Their orientation then improved when approaching land, suggesting that birds must consult an olfactory map when out of sight of land but are subsequently able to find home using familiar landscape features.