Behavioural Processes 109 (2014) 64–69 Contents lists available at ScienceDirect Behavioural Processes jo ur nal home p ag e: www.elsevier.com/locate/behavproc Effect of light intensity on food detection in captive great fruit-eating bats, Artibeus lituratus (Chiroptera: Phyllostomidae) Eduardo de A. Gutierrez a,∗ , Valdir F. Pessoa a , Ludmilla M.S. Aguiar b , Daniel M.A. Pessoa c a Laboratory of Neurosciences and Behavior, Department of Physiological Sciences, University of Brasilia, Brasilia, DF 70910-900, Brazil b Laboratory of Biology and Conservation of Bats, Department of Zoology, University of Brasilia, Brasilia, DF 70910-900, Brazil c Laboratory of Sensory Ecology, Department of Physiology, Federal University of Rio Grande do Norte, Natal, RN 59012-350, Brazil a r t i c l e i n f o Article history: Available online 19 August 2014 Keywords: Foraging behavior Lunar phobia Neotropical bat Nocturnal vision a b s t r a c t Bats are known for their well-developed echolocation. However, several experiments focused on the bat visual system have shown evidence of the importance of visual cues under specific luminosity for different aspects of bat biology, including foraging behavior. This study examined the foraging abilities of five female great fruit-eating bats, Artibeus lituratus, under different light intensities. Animals were given a series of tasks to test for discrimination between a food target against an inedible background, under light levels similar to the twilight illumination (18 lx), the full moon (2 lx) and complete darkness (0 lx). We found that the bats required a longer time frame to detect targets under a light intensity similar to twilight, possibly due to inhibitory effects present under a more intense light level. Additionally, bats were more efficient at detecting and capturing targets under light conditions similar to the luminosity of a full moon, suggesting that visual cues were important for target discrimination. These results demonstrate that light intensity affects foraging behavior and enables the use of visual cues for food detection in frugivorous bats. This article is part of a Special Issue entitled: Neotropical Behaviour. © 2014 Elsevier B.V. All rights reserved. 1. Introduction The order Chiroptera is the second most diverse taxon among the class Mammalia, comprising approximately 1200 living species (Simmons, 2005), which are uniquely capable of powered flight. Most bats are nocturnal, and 17 of the 18 chiropteran families possess the ability of laryngeal echolocation (Altringham, 2011), an important adaptation for navigating in the dark. These characteris- tics, along with relatively small and sometimes even inconspicuous eyes (Altringham and Fenton, 2003), have given rise to the question of how developed is the bat visual system and when vision may be useful for these animals. The importance of the visual system for echolocating bats has been the subject of many studies since the 1960s. So far, researchers have found evidence that visual cues are used during homing (Davis, 1966; Williams and Williams, 1970; Williams et al., 1966), diurnal navigation (Layne, 1967), pattern ∗ Corresponding author. Present address: Department of Ecology and Evolutionary Biology, 25 Harbord Street, RW 501, University of Toronto, Toronto, ON M5S 3G5, Canada. Tel.: +1 647 867 4062. E-mail addresses: e.dealmeidagutierrez@mail.utoronto.ca (E.d.A. Gutierrez), vpessoa@unb.br (V.F. Pessoa), ludmillaaguiar@unb.br (L.M.S. Aguiar), pessoadma@cb.ufrn.br (D.M.A. Pessoa). discrimination (Suthers et al., 1969), obstacle avoidance (Bradbury and Nottebohm, 1969; Chase and Suthers, 1969; Orbach and Fenton, 2010), escape behavior (Chase, 1981, 1983; Davis and Barbour, 1965) and location of roosting sites (Ruczy ´ nski et al., 2011). Researchers have also focused on the use of vision for foraging in echolocating bats, particularly for prey detection and capture (Bell, 1985; Bell and Fenton, 1986; Eklöf and Jones, 2003; Eklöf et al., 2002; Rydell and Eklöf, 2003). It has been shown that the insect- eating bat Macrotus californicus preferentially uses vision to locate prey under light levels similar to that of the full moon (Bell, 1985) and has good visual acuity, even under very dim light (Bell and Fenton, 1986). More recently, studies have identified that achro- matic cues (Eklöf et al., 2002) as well as an insect’s wingspan (Rydell and Eklöf, 2003) are important features that facilitate the use of vision by the insectivorous bat Eptesicus nilssonii: the greater the contrast between prey and background and the larger the insect wingspan, the easier prey detection is. Additionally, the insect- eating bat Plecotus auritus can use vision for prey detection under a light intensity of 4 lx and prefers to use visual cues when foraging (Eklöf and Jones, 2003). Nevertheless, little is known about the use of vision for food location by frugivorous bats. Fruits from some bat-dispersed plants, such as many of the genus Piper and the Gurania spinulosa, http://dx.doi.org/10.1016/j.beproc.2014.08.003 0376-6357/© 2014 Elsevier B.V. All rights reserved.