The relative importance of olfaction and remote touch in prey detection by North Island brown kiwis

Birds that forage by probing in sand, soil or mud substrates must often use senses other than vision to find their prey. Kiwis (Apterygidae) are nocturnal probing birds inhabiting forested areas in New Zealand. Their visual sense is reduced, but they have a highly developed sense of smell, a bill tip organ similar to that found in Scolopacidae shorebirds, which may be used to detect vibrotactile cues produced by burrowing prey (remote touch), and prominent ear openings. We designed a foraging experiment presenting mealworm prey to eight captive North Island brown kiwis, Apteryx mantelli, under a variety of trial conditions to discover whether they were using hearing, olfaction, remote touch or direct touch (chance alone), singly or together, to find prey. Kiwis were most efficient at finding prey using olfaction alone or in combination with other cues, but switched to locating prey with lower efficiency using remote touch, in the absence of olfactory cues. They did not appear to use auditory cues for foraging. The ability to switch between sensory modalities depending on the quality of the cues available has been documented before in other groups of birds (including thrushes (Turdidae) and sandpipers (Scolopacidae)) and would be of great advantage to wild kiwis foraging under a wide range of environmental conditions.