J. Avian Biol. 41: 350353, 2010 doi: 10.1111/j.1600-048X.2010.05138.x # 2010 The Authors. J. Compilation # 2010 J. Avian Biol. Received 28 January 2010, accepted 12 April 2010 Remote touch prey-detection by Madagascar crested ibises Lophotibis cristata urschi Susan J. Cunningham, Isabel Castro, Thomas Jensen and Murray A. Potter S. J. Cunningham (s.j.cunningham@massey.ac.nz), I. Castro and M. A. Potter, Inst. of Natural Resources, Massey Univ., Private Bag 11-222, Palmerston North, New Zealand.  T. Jensen, San Diego Zoo’s Inst. for Conservation Research, 15600 San Pasqual Valley Road, Escondido, CA 92027, USA. Birds that forage by probing must often rely on sensory systems other than vision to detect their buried prey. Such senses may include hearing (e.g. Australian magpies (Atramidae), American robins (Turdidae)) or chemical senses/olfaction (e.g. kiwi (Apterygidae) and some shorebirds (Scolopacidae)). Probe foraging kiwi and shorebirds are also able to use vibrotactile cues to locate prey buried in the substrate at some distance from their bill-tips (‘remote touch’). These birds possess an organ consisting of a honey-comb of sensory pits in bone of the bill-tips, packed with mechanoreceptive nerve ending (Herbst corpuscles). Such a bill-tip organ has recently also been described in ibises (Threskiornithinae), but its function not elucidated. We designed a foraging experiment presenting mealworm prey to three captive Madagascar crested ibises Lophotibis cristata urschi under a variety of trial conditions to discover whether they were using remote touch, mediated by their bill-tip organ; chemosense/olfaction; or hearing to locate buried prey. The ibises were reliant on remote touch for prey detection  the first time this sensory system has been demonstrated for this group of birds. They did not appear to use hearing or chemical senses/olfaction to aid in prey detection. Birds are generally thought to rely heavily on vision for most aspects of their lives (Silman 1973), but vision can be of little use when foraging for prey hidden in sand, soil, mud, or turbid water. While tracks, burrows and substrate disturbance may visually indicate the location of some prey items, probe-foraging birds must often rely on non-visual sensory systems to locate their food. Bird species from a wide range of families (e.g. Scolopacidae; Apterygidae; Turdidae; and Atramidae) use varying sensory systems to locate buried prey. For example, American robins Turdus migratorius and Australian magpies Gymnorhina tibicen use auditory cues to find prey when visual cues are not available (Floyd and Woodland 1981, Montgomerie and Weatherhead 1997). Probe-foraging sandpipers use chemosensory systems such as taste and, perhaps, olfaction (Gerritsen et al. 1983, Van Heezik et al. 1983), chance location (directly touching prey while probing), and a sensory system called ‘remote touch’ to locate prey items. Remote touch is based on the intercep- tion of vibrotactile signals from burrowing invertebrates, or pressure disturbances caused by sessile prey (Gerritsen and Meiboom 1986, Piersma et al. 1998). Nocturnal, probe- foraging kiwi (Apteryx spp.) use olfaction (Wenzel 1968, 1971) and remote touch (Cunningham et al. 2009) to find food. In both sandpipers and kiwi, the remote touch sense is mediated by an organ comprised of numerous pits in the bone of the bill-tips packed with vibration-sensitive mechanoreceptors (Herbst corpuscles) (Bolze 1968, Piersma et al. 1998, Nebel et al. 2005, Cunningham et al. 2007). Ibises (Ciconiiformes: Threskiornithinae) are usually described as ‘tactile’ hunters because of their method of foraging by probing into sediments and probing and sweeping in water (Kushlan 1978). Some studies of ibis foraging have assumed ‘tactile’ means that prey can only be detected by direct contact with the bill-tips, and that the time involved in chasing prey once discovered is therefore negligible (Kushlan 1979). Ibises, however, possess a bill-tip organ similar in structure to that found in the Scolopacidae and Apterygidae (Cunningham et al. 2010) suggesting they may also detect prey using remote touch, although this has not been tested for any ibis species. Bony pits like those of shorebirds, kiwi and ibises, have been described from the bill-tip of the black-faced spoonbill Platalea minor (Ciconiiformes: Plataleanae) (Swennen and Yu 2004), although no histological work has been carried out to verify these pits contain mechanoreceptors. Observations of the feeding behaviour of this species suggest it may use remote touch to sense prey in the water (Swennen and Yu 2005). Spoonbills (Plataleanae) and ibises (Threskiornithinae) are closely related, together comprising the family Threskiornithidae. The possibility that spoonbills may use remote touch increases the likelihood that this sense might also be employed by ibises. 350