Contributions to Zoology, 69 (3) 147-155 (2000) SPB Academic Publishing bv, The Hague of Jameson’s mamba Large elapids and arboreality: the ecology green (Dendroaspis jamesoni) in an Afrotropical forested region Luca Luiselli¹’²,Francesco+M. Angelici¹’² & Godfrey+C. Akani³ 1 DEMETRA - Institute ofEnvironmental Studies, Via dei Cochi 48/B, 1-00133 Rome, Italy, and Italian Foun- 2 dation of Vertebrate Zoology, Via Cleonia 30, 1-00152 Rome, Italy, e-mail: [email protected]; Ecology Re- search Group (NFC-FIZV), No. 4 Adak Uko Street, Calabar, Cross River State, Nigeria; department of Biological Sciences, Rivers State University of Science and Technology, P.M.B. 5080, Port Harcourt, Rivers State, Nigeria Keywords: Dendroaspis jamesoni, Elapidae, snakes, ecology, Nigeria Abstract Food habits 150 Reproductive biology 150 Discussion 151 Several mamba aspects of the ecology of Jameson’s green Acknowledgements 153 Dendroaspis jamesonijamesoni (Traill, 1843), a large-sized References 154 arboreal elapid snake, are studied in southern Nigeria. This species 18 common and widespread in the region studied. On the basis of the the analysis of both the habitats of capture of various specimens and the results of a logistical regression model, it Introduction seems that this species inhabits a wide variety of habitats (including secondary forest patches and the plantation-forest One of the contextual typical corollary presence mosaic), and that its local distribution is not influencedby the of toxic venom and size in snakes Presence of macrohabitat Green mambas highly impressive any parameter. were in these observed in the and in the without is interest Thus, it is both dry wet season, any great public species. statistical of bias toward a particular season. Adult sex-ratio was not surprising that, compared with most the a females. Pproximately 1 : 1. Maleswere significantly longer than the African snake species, large-sized highly ven- All adult mamba dietary records involved warm-blooded prey omous mambas (genus Dendroaspis: Elapidae) are lizards (mainly birds), whereas young mambas fed also upon well-known and relatively (e.g. see Schmidt, 1923; toads. all the adult mambas were Nearly prey eaten by lonides and arboreal, and thus for the recent Wakcman, 1955; Isemonger, 1962; there was no support hypothesis that adult mambas develop anorientationto forageon terrestrial Pitman, 1965; Lloyd, 1974; Pitman, 1974; Villiers, rodents. combats and observed in Male-male matings were 1975; Branch, 1988; Phelps, 1989; Angilletta, 1994; December, January, and February (dry season), and gravid Branch et ah, 1995, and references therein; Spawls females were collected in April, May, and June (wet season). and Branch, 1997). Females 7-16 and litter size was produced eggs (mean 10.9), The continuous forest zone in southern Positively correlated with maternal length. Nigeria is inhabited by Jameson’s green mamba, Dendro- aspis jamesoni jamesoni ( cf. Villiers, 1975; But- Contents ler and Reid, 1986, 1990; Spawls and Branch, 1997; Luiselli et al., 1998c), and possibly by the west- tf Abstract D. viridis 147 ern green mamba, (Villiers, 1975; Spawls Introduction 147 and Branch, 1997). The latter species, however, Materials and methods 148 was never found by us during our long-term field Study area 148 research in this African country (Akani et al., 1999). Data collection 148 The present paper provides detailed ecological data Analyses 148 Results 149 on the Jameson’s green mamba in southern Nige- Habitat and ecological distribution 149 ria, and compares the collected data with those Seasonal distribution of records 149 available for other large elapid snakes from Af- Population size and density 149 rica and elsewhere. Sex ratio and sexual size dimorphism 150 Downloaded from Brill.com10/05/2021 05:24:21PM via free access Akani - mamba 148 L. Luiselli, F.M. Angelici & G. C. Ecology ofJameson’s green Materials and methods Meteorological conditions, time (Lagos time), and habitat of each observation were recorded. Specimens found already dead (roadkilled or machetedby farmers), including those which were Study area too damaged for any reliable body size measurement, were inspected by dissection for data on diet and reproductive condition. The field study was carried out mainly from September 1996 to The same was true for some preserved specimens found in 1999, with some data recorded evenearlier, in some collections of February museum (Rivers State University Port Harcourt, localities ofsouthern These localities situated in Nigeria. were and Cross River National Park of Akampka) and in the the territories ofthe Delta Edo, and Rivers Niger (Delta, Bayelsa, laboratories ofseveral high schools and hospitals (cf. “Acknowl- in Anambra State, Abia State, Akwa-lbom State, Imo States), edgements”), where these specimens were transitorily stored to These territories in State, and Cross River State (Fig. are 1). be used for demonstration to students. Free-ranging snakes were with ofrainforest general heavily populated, patches interspersed captured with the help of grabsticks, given the arboreal habits wide banana, among plantations (yam, cassava, cocoa, pineapple, and the extremely dangerous nature of this species which is plantain, oil palm, The forest patches have dry soil, etc.). may well-known to be highlyvenomous(Spawls and Branch, 1997), or may be permanently or inundated earlier seasonally swamp-forests. but, contrary to reports, not very aggressive (Luiselli, Enormous extensions of formations (Avicennia mangrove marina, Akani and Angelici, unpubl. obs.). All snake specimens captured racemosa) are found in the brackish water tracts, Rhizophora alive were palpated in the abdomen until regurgitation of the the rivers mainly along Benin,Forcados, Ramos, Sangana, Nun, food defecation had occurred. The items ingested or prey were Saint San Brass, Nicholas, Santa Barbara, Bartholomew, identified the When the in to lowest taxon possible. prey was Sambreiro, New Calabar, Bonny, Imo, Kwa-lbo, and Cross. good condition, it was weighedby an electronic balance (to 0.1 of both environmental characteristics Much details study areas In these the measured. g precision). cases, also snake mass was and climate conditions are described elsewhere (Luiselli et al,, Voucher specimens are deposited in the herpetological collections 1998a, 1998b, 1998c). of the authors (L.L. and F.M.A., collections in Rome and in Ikot-Ekpene, Nigeria; G.C.A., collection in Port Harcourt, Nigeria), in the collections of the “Monti Prenestini Natural History Museum” (Capranica Prenestina, Rome), and in the collection ofthe Department ofBiological Sciences, Rivers State University of Science and Technology, Port Harcourt. Analyses size mambas Population and density of green were estimated by capture-mark-recapture procedures in a moist rainforest area of southeastern Nigeria (Eket, Akwa-lbom State). The surface of the area used for the capture-mark-recapture procedure was 100 ha. The capture-mark-recapturestudy lasted 109 days, from early June to late September 1997. Snakes were individually marked by ventral scale-clipping, andpainted with a white number on the back for furtherobservations at distance without necessity of We considered as = recaptures. “recaptures” (second sample) Fig. I. Map of Nigeria showing the study area. P.H. Port all ofthe later ofmarked individu- Harcourt city. sightings (i.e. dorsallypainted) als, when at least 10 days from the date of the first capture had passed. Population density was calculated by applying the Lincoln- Data collection Petersen index, with its relative 90% confidence limits (Caughley, 1977; Seber, 1982). For population size estimates, only adult Field trips were conducted in all types of weather. Each day, specimens were considered. The Lincoln-Petersen index was the field research from 8 6 lasted approximately a.m. to p.m, used under the assumption that our mambapopulation wasnearly (Lagos time). Night searches were done only rarely, because of without emi/immigrants. In fact, the study area is surrounded constraints security related to the prevailing unstable political in part by a large river (Kwa-lbo River) and in part by much situation. Random routes to followed deforested that crossed locate snakes were areas, are hardly by green mambas. throughout macrohabitat every type available in each study area. The effects of the macro-environmental parameters on the The captured snakes sexed and were measured for snout-vent presence/absence ofD. jamesoni in the study region wereassessed length (SVL, to the nearest 1 and conditional cm) tail length (tL). Since a by usinga logistic regressionmodel (forward stepwise negligibleproportion ofspecimens had the tail broken (< 0.5%), procedure) for discrete values (Hosmer and Lemeshow, 1989). for all analyses we considered the total i.e. + length, SVL tL. For this analysis, we used data ofpresence/absence ofthe green Downloaded from Brill.com10/05/2021 05:24:21PM via free access Contributions to Zoology, 69 (3) - 2000 149 mamba in 52 sites which = study were accurately surveyed during and suburban areas (« 4, 4.8%). As for the pre- our environmental works (Anonymous, 1998). The surface of served specimens observed in high school and each site was approximately 50 ha, and was separated from the hospital collections (n = 11), it was impossible to closest surveyed site by at least 10 km oflinear distance. Eight establish the habitat of capture. However, based macro-environmental parameters were identified during these on interviews