Female tannin avoidance: a possible explanation for habitat and dietary segregation of gira¡es (Gira¡a camelopardalis peralta)inNiger Lauren E. Caister1,William M. Shields2 and Allen Gosser3 1SUNY College of Environmental Science & Forestry,133 IllickHall,1Fo restry Dr, Syracuse, NY13210, USA, 2SUNY College of Environmental Science & Forestry,1Forestry Drive, Syracuse, NY13210, USA, 3USDA, APHIS,WS,1930 Rout 9, Castleton, NY 12033, USA les re¨ gions qu'elle occupe actuellement. L'habitat actuel Abstract de saison se© che comprend deux zones de ve¨ ge¨ tation dis- Niger is host to the last free-roaming herd of G.c. peralta tinctes. Dans les deux zones, les girafes doivent cohabiter (Gira¡a camelopardalis peralta).We examined the foraging avec les gens de la re¨ gion. Les girafes pre¨ sentent une se¨ g- preferences of these gira¡e in their dry-season habitats, re¨ gation sexuelle tant dans la se¨ lection de l' habitat de with the goal of preserving the herd in the regions that saison se© che que dans les choix alimentaires. Les femelles they currently inhabit. The current dry-season habitat allaitantes manifestent une forte pre¨ fe¨ rence pour la zone comprises two distinct vegetation zones. In both of these interme¨ diaire (IM). Les maª les et les femelles pleines mon- zones the gira¡e must exist alongside the people of this trent une pre¨ fe¨ rence pour le Dallol Bosso (DB). Les region. The gira¡es exhibit a sexual segregation in their femelles qui s'occupent de jeunes e¨ vitent visiblement les dry-season habitat selection and forage choices. The tanins. Les maª les et les femelles sans jeune pre¨ fe© rent un females show a strong preference for the intermediate fourrage riche en prote¨ ines et en graisses, tandis que les zone (IM) when lactating. The males and pregnant subadultes manifestent une forte pre¨ fe¨ rence pour un females show a preference for the Dallol Bosso (DB). Nur- contenu e¨ leve¨ en prote¨ ines et en hydrates de carbone et sing cows exhibit an avoidance of tannins. Bulls and des taux de tanins mode¨ re¨ s. Combretum glutinosum est non-nursingcows prefer high proteinand high fat forage, l'espe© ce pre¨ fe¨ re¨ e des adultes des deux sexes dans la IM. while subadults showa strong preference forhighprotein Les maª les et les femelles pre¨ fe© rent nettement Acacia nilo- and carbohydrate contents and moderate tannin levels. tica et Acacia seyal dans le DB. Les subadultes des deux Combretum glutinosum is the preferred species for adults sexes pre¨ fe© rent nettement Prosopis africana dans la IM. of both sexes in the IM. Males and females have strong Contrairement aux femelles, les maª les conservent leur preferences for both Acacia nilotica and Acacia seyal in pre¨ fe¨ rence pourA. nilotica lorsqu'ils sont dans la IM. the DB. Sub-adults of both sexes strongly prefer Prosopis africana in the IM. Unlike females, males retain their pre- ference forA. nilotica when in the IM. Introduction Keywords: foraging preference, gira¡e, G.c. peralta, Gira¡a Niger is home to the last free-roaming herd of gira¡es camelopardalis, Niger, west African browsers. (Gira¡a camelopardalis peralta) in west Africa and the last free-roaming herd of the race peralta. The herd in Niger Re¨ sume¨ decreased throughout the 1960s and 1970s. The severe Le Niger abrite la dernie© re population sauvage de Gira¡a droughts of the 1970s and 1980s in Niger helped to camelopardalis peralta. Nous avons e¨ tudie¨ les pre¨ fe¨ rences further degrade the landscape and decimate wildlife alimentaires de ces girafes dans leurs habitats de saison populations. Prior to the droughts, the gira¡es were se© che, dans le but de maintenir cette population dans widespread and abundant in Niger (Ciofolo, 1995). After the droughts, the gira¡es were forced into a small area surrounding the Koure¨ region and the Dallol Bosso, Correspondence: Dr William Shields. E-mail: [email protected] between Bale¨ yara and Birnin Gaoure¨ .While this de¢nes # 2003 African Journal of Ecology, Afr. J. Ecol., 41,201^210 201 202 Lauren E. Caister et al. the group's current range, some long distance move- Data collection ments by lone adults have been observed (Le Pendu & Ciofolo,1999). Every gira¡e was identi¢ed through a detailed photo log. The gira¡es now inhabit the Harikanassou region, The gira¡es were photographed from both sides and where they were rarely seen before, and are now inter- assigned identi¢cation numbers at ¢rst sighting. When acting regularly with humans. They are protected from possible, the entire body,and in every instance the entire hunting in Niger,where killing a gira¡e is now a criminal neck, was photographed. The original photo record was o¡ence.The region has no natural gira¡e predators other initiated by Peace Corps Volunteer Paul Peterson in than man, and only domestic herbivores as potential 1995, revamped by PURNKO ^ a Dutch conservation competitors. The occupancy of a new range, combined organization ^ in 1996 and continued by our team. We with the government'sinterest in developing ecotourism, also recorded pertinent information about the gira¡es inspired us to undertake a study of gira¡es in the region. (i.e.sex,injuries,o¡spring,maternities,agesanddeaths). A dietary assessment of the herd was requested by Peace The photographic record allowed us to determine the Corps Niger on behalf of the government of Niger. The age of each gira¡e for the duration of the study. Gira¡es preliminary questions we hoped to explore included: (i) were designated as adults (>4 years old), subadults Where were the gira¡es living and what were they eating (between 18 months and 4 years old), juveniles (6^ in their new range? (ii) Why had the gira¡es settled in 18 months old), and newborns (<6 months old). Their this region, and (iii) What, if anything, could be done to ages were determined based on known dates of birth or help ensure their continued presence? on the age of the individual at the ¢rst recorded sighting and/or photograph (some of which dated back to 1990). Methods Foster (1966) ¢rst developed the concept of the photo- record. As he noted, coat patterns on gira¡es do not change with age, and are unique to each individual. Study site The gira¡es were tracked visually while driving The gira¡es inhabit three vegetation zones in their core Yamaha 125 cc dirt bikes. We selected the closest gira¡e range. The core range is subdivided into dry season and for focal animal observation, but tried not to sample the wet season habitats. The dry season habitat is in the same animal more frequently than others in the herd. Koure¨ ^Harikanassou region (termed the intermediate Each location where the gira¡es were ¢rst encountered zone) and the Dallol Bosso. The average annual rainfall was recorded using a Grumman hand-held geographical of between 400 mm and 500 mm de¢nes this region as positioning systems (GPS). Most of our observations part of the Sahel. The herd is there from October to May, were made during the early morning (07.00^11.00 h). after which they congregate in the Koure¨ region follow- We did not observe the gira¡es eating after noon. They ing the ¢rst rains. The herd is widespread in the dry sea- spent most of their time resting in the shade until early son habitat.We worked in the Harikanassou area, about evening, presumably due to the high air temperatures, 85km south-east of Niamey,fromJanuary1997to Febru- which often reached 49 8C. This was not true during the ary1999. cold-season (late December^February), when the gira¡es The Dallol Bosso (DB) is an ancient riverbed with a could be observed foraging until late afternoon. During shallow water table, as shallow as 0.5 m in the valleys each focal sample we recorded: (1) the species of each and hollows. Many large, permanent waterholes and food item, (2) the height of each feeding bout, (3) the ponds also characterize this region. These ponds are duration of each feeding bout in seconds, (4) which part often shallow (<1.5m deep) and marshy. This zone is of the plant was being taken, (5) the individual focal ani- marked by comparatively fertile soils and an abundance mal,and(6) the identityofallof the othergira¡espresent of trees and tree species around the wetlands. The inter- (modi¢ed fromYoung & Isbell,1991). mediate zone (IM) is more typical of the Sahel. It has To document the available vegetation, 20 plots were sandy soils, scattered trees and low scrub brush. Most of randomly selected from the entire study area. An addi- the region is farmed in the rainy season and left fallow tional ¢ve plots were each randomly selected from the during the dry season. This area has a deep water table, Dallol Bosso (DB) and Intermediate Zone (IM).We selec- often being as much as 50^60 m down. ted an extra two plots in the IM which were frequented # 2003 African Journal of Ecology, Afr. J. Ecol., 41,201^210 Female tannin avoidance in giraffes 203 Table1 Known chemical compositions of plants in the G.c. peraltas'dry-season habitat in Niger, from dry weight samples %Crude %Crude Tannin Protein % Fats Fibre % Ash % Moisture % NFE Sourcey Content Acacia species A. nilotica 12.9 5.1 13.7 1.1 52.0 32.2 (1) Pods 30% (2)ÃÃ Bark 20.0% (2) A. senegal 28.6 3.0 16.2 0.4 61.0 19.8 (1) A. seyal 18.5 ^ ^ ^ ^ ^ (2) Pods 20% (2) Bark 20% (2), 18^30%(5) Annona senegalensis 8.2 ^ ^ ^ 10.5 ^ (3) Balanites aegyptica 14.25 0.82 2.91 11.72 4.16 66.14 (4) Combretum glutinosum 10.0 1.02 1.82 14.15 5.04 67.97 (4) Faibherbia albida 13.63 0.77 2.15 12.75 3.88 66.82 (4) Bark 20^28% (2) Guiera senegalensis 13.13 0.18 1.55 11.46 4.06 69.62 (4) Piliostigma reticulatum 9.38 0.63 2.89 10.12 5.05 71.93 (4) Bark 18% (2) Prosopis africana 10.2 6.8 ^ ^ 7.9 49.46 (3) Bark 18% (2) (seeds) 16.0^25.74 1.7^20.0 7.6^15.76 2.94^3.4 ^ 35.56^78.5 (5) ÃAll values apply to dry matter weight of leaves, unless otherwise noted.