American Journal of Primatology 70:892–896 (2008) BRIEF REPORT Wild Mouse Lemurs Revisit Artificial Feeding Platforms: Implications for Field Experiments on Sensory and Cognitive Abilities in Small Primates MARINE JOLY Ã , MARINA SCHEUMANN, AND ELKE ZIMMERMANN Institute of Zoology, University of Veterinary Medicine, Hannover, Germany Dealing effectively with space to find important resources in a natural environment is a fundamental ability necessary for survival. Evidence has already been provided that wild gray mouse lemurs revisit stationary feeding sites regularly. In this study, we explore to what extent two sympatric mouse lemur species, Microcebus murinus and M. ravelobensis, revisited artificial feeding sites during a period of food scarcity. As the tested populations are marked with individual transponders, we built up artificial feeding platforms equipped with a transponder reader at nine different locations where mouse lemurs had been previously caught. We baited them with a liquid reward and recorded the visitors’ ID, the time and frequency of their visits, as well as all encounters that occurred on the platforms. Only mouse lemurs visited platforms and a total of sixteen individuals across both species were identified. Mouse lemurs visited a platform with a frequency of 2.02 (70.95, range: 1–3.4) times in a night and they revisited it on several consecutive nights following their first visit (percentage of revisits 90.6%711.7, range: 73.3–100%). First visits on a platform occurred on average 44 min (735; range: 13–131) after sunset. We identified encounters between mouse lemurs on platforms: all of them were agonistic and within a species. Within a dyad, chasers were significantly heavier than chasees (N 5 7 dyads). Our design of platform experiments offers the advantage of observing wild individually known small primates in their natural environment and of setting up controlled experiments to gain insight into their sensory and cognitive abilities. Am. J. Primatol. 70:892–896, 2008.  c 2008 Wiley-Liss, Inc. Key words: Microcebus murinus; field experiment; foraging strategy; sympatric species; prosimian INTRODUCTION Dealing effectively with space to find important resources (such as food, nests and burrows) in a natural environment is a fundamental ability neces- sary for survival. So far, a large number of studies have addressed the problem as to what extent nonhuman captive or wild monkeys and apes remember and revisit locations where they have previously found food [see for reviews, Janson & Byrne, 2007; Tomasello & Call, 1997]. Information on whether strepsirhine primates revisit and re- member locations is scarce. Mouse lemurs are small, nocturnal Malagasy lemurs belonging to strepsirhine primates [Mittermeier et al., 2006]. In nature, they face marked seasonality and therefore a huge variation in food availability within a year [see Jury, 2003]. They forage solitarily during the night and exploit mostly tree gums and homopteran larvae secretions during the dry season, whereas they eat fruits, nectar and flowers during the rainy season [Hladik et al., 1980; Martin, 1973; Radespiel et al., 2006]. Remembering and revisiting sites with key- stone resources should thus be advantageous to cope with seasonal food fluctuations. In the field, we demonstrated that mouse lemurs revisited the same individual gum trees during a period of food scarcity [Joly & Zimmermann, 2007]. Nevertheless, to assess more information about mechanisms underlying foraging strategies, controlled field experiments are needed [see Janson & Byrne, 2007]). In this study, we designed artificial feeding platforms (FPs) and installed them in the habitat of two sympatric species of mouse lemurs. As the tested mouse lemur populations are marked with individual transpon- ders, FPs with a passive transponder reader allowed for automated animal identification. The aim of the experiment was to test to what extent mouse lemurs will revisit a platform containing a stationary liquid food reward used successfully in experimental studies on mouse lemurs in captivity [see e.g. Joly Published online 16 June 2008 in Wiley InterScience (www. interscience.wiley.com). DOI 10.1002/ajp.20560 Received 7 December 2007; revised 4 April 2007; revision accepted 16 April 2008 Contract grant sponsors: DAAD; University of Veterinary Medicine Hannover. Ã Correspondence to: Marine Joly, Institute of Zoology, University of Veterinary Medicine, Buenteweg 17, 30559 Hannover, Germany. E-mail: marine.joly@tiho-hannover.de r r 2008 Wiley-Liss, Inc.