The Herpetological Journal
Total Page：16
File Type：pdf, Size：1020Kb
Volume 2, Number 2 April 1992 ISSN 0268-0130 THE HERPETOLOGICAL JOURNAL Published by Indexed in THE BRITISH HERPETOLOGICAL SOCIETY Current Contents The Herpetological Journal is published quarterly by the British Herpetological Society and is issued free to members. Applications to purchase copies and/or for details of membership should be made to the Hon. Secretary, British Herpetological Society, The Zoological Society of London, Regent's Park, London, NW l 4RY, UK. Instructions to authors are printed inside the back cover. All contributions should be addressed to the Editor (address below). Editor: Richard A Griffiths, The Durrell Institute of Conservation and Ecology, University of Kent, Canterbury, Kent, CT2 7NX, UK. Assistant Editor: Margaret M. Bray, Department of Biochemistry and Biological Sciences, Wye College (University of London), Nr. Ashford, Kent, TN25 5AH, UK. Editorial Board: Pim Arntzen (Leicester) Donald Broadley (Zimbabwe) John Davenport (Millport) Tim Halliday (Milton Keynes) Michael Klemens (New York) Colin McCarthy (London) Andrew Milner (London) Henk Strijbosch (Nijmegen) Richard Tinsley (London) BRITISH HERPETOLOGICAL SOCIETY Copyright It is a fundamental condition that submitted manuscripts have not been published and will not be simultaneously submitted or published eleswhere. By submitting a manuscript, the authors agree that the copyright for their article is transferred to the publisher if and when the article is accepted for publication. The copyright covers the exclusive rights to reproduce and distribute the article, including reprints and photographic reproductions. Permission for any such activities must be sought in advance from the Editor. ADVERTISEMENTS The Herpetological Journal accepts advertisements subject to approval of contents by the Editor, to whom enquiries should be addressed. FRONT COVER: Galapagos giant tortoise, Geochelone elephantopus (I. Swingland). 37 HERPETOLOGICAL JOURNAL, Vol. 2, pp 37-42 (1992) FEEDING STRATEGIES OF THE VIPER VIPERA URSINII URSINII (REPTILIA: VIPERIDAE) IN THE APENNINES UMBERTO AGRJMI AND LUCA LUISELLI* Istituro Superiore di Sanita. Roma Italy *Co"espondence address: Luca Luisel/i, via Olona 7. 00198 Roma, Italy. (Accepted 21.6. 90) ABSTRACT During a three-year period of research on the viper Vtpera ursinii ursinii, observations on diet composition and feeding strategies were obtained. The major food items in terms of percentage were orthopterans, followed by rodents, lizards, birds, spiders and beetles. A considerable seasonal change in the diet composition was noted: invertebrates predominated in the diet only between July and September, as compared to the spring diet which was made up of vertebrates. INTRODUCTION potential prey are to be found in the habitats of these mountain vipers, including one species of Lacertidae Numerous works have reported data regarding (Podarcis muralis), two bird species (bearing in mind that various aspects of the ecology of Vtpera ursinii, including Anthus s. sp inoletta and Phoenicurus ochruros are the only Baron (1980, 1989), N aulleau ( 1973, 1984), Kotenko species that nest at ground level in the valleys inhabited (1989), Saint Girons (1975, 1978, 1979, 1980) and Saint by V. ursinii and therefore may be prey to these snakes), Girons and Naulleau (1981). The most recent studies on and some invertebrates (particularly Orthoptera). the feeding behaviour of these vipers have been carried The small mammals of the studied areas are less out by Baron (1989) on Mont Ve ntoux (France) and by known, and therefore we have not a complete list of the Kotenko (1989) in various areas of the Ukraine, such as species inhabiting these environments; however, we the Orlova island. However, the feeding patterns of the have found in the viper stomachs only seven specimens Italian viper populations, restricted as they are to a few of a Microtidae species. Since these remains had been of the Apennine massifs, are not very well-known, and particularly damaged by the digestive process, we have have been discussed only in general, layman's works not identified the species in question, but, referring to whose observations seem to lack a systematic approach To schi's (1965) keys and to Grafs (1982) data, we believe (cf. for example Bruno and Maugeri, 1977, 1984; Bruno that the rodent in question might be Microtus nivalis. 1983). The vipers over 28 cm long were palpated in order to The aim of this paper is therefore to present a make them regurgitate their ingested prey, and were systematic study carried out over a number of years on then immediately released. Since this operation may be the fe eding activities of V. ursinii in the central dangerous for smaller specimens, these were analysed Apennines, in the hope that these data may prove of using Kjaergaard's method (1981). interest in providing a better knowledge of certain Unfortunately, these methods do not always allow for aspects of the biology of this mountain viper. the examination of all the gut contents. In order to overcome this problem it was necessary to analyse the MATERIALS AND METHODS faeces of 34 other vipers (all excluded from the total number of specimens quoted earlier, and all belonging The vipers were observed during the whole of their to category 1). active cycle, i.e. from mid April until the end of Often it was possible to obtain more than one prey September each year from 1987 to 1989. All the data item from a single specimen, so the overall number of reported in this paper were obtained by analysing the prey is considerably higher than the total number of gastrointestinal contents of V. ursinii specimens captured animals caught (95 prey obtained from 43 specimens in two locations in the Abruzzi Apennines (Valle di belonging to category 1 and ·14 prey taken from seven Campo Imperatore, Gran Sasso d'Italia; monte Ve lino), specimens in category 2). at an altitude ranging from 1600 to 1850m. The ingested biomass was calculated by applying the The vipers were divided into two categories according same methods utilized by Brana et al. (1988), that is to to size: (I) vipers longer than 28 cm in total length and say considering the "fresh" weight of the ingested prey if (2) vipers shorter than 28 cm in total length. 76 vipers it was in very good condition. Obviously, when using the were examined in the first category (of which 43 had "fresh" weight there is the possibility that the weight identifiable food residuals in their gastrointestinal may be underestimated. This risk was avoided by using apparatus; x = 56.6%) and 12 in the second category (of this method only in a limited number of cases where the which 7 had food remains in the intestine x = 58.3%). ingested prey had not been at all damaged by the On the whole, the ingested matter was easily digestive process (21.1% of the cases). recognizable, mainly because only a few species of 38 UMBERTO AG RIMI AND LUCA LUISELLI The food niche breadth (B) was calculated using Simpson's (1949) diversity index: o/o 80 where p1 = the frequency with which each ith prey category was used. With this formula, all the Orthoptera 60 remains were included in one category, while the other categories were made up of Microtidae, Motacillidae, Lacertidae, Coleoptera and Opilionidae. In order to be able to study the fe eding periods and 40 - the frequency of meals, 21 specimens (8 males and 13 females and all belonging to category 1) were marked and then released into a confined area (of approximately 1.5 hectare) with a superimposed grid 20 system, situated in the Valle di Campo Imperatore (Gran Sasso) at approximately 1750m. The 21 vipers were marked by scale-clipping, and were excluded from the number (N = 76) of vipers over 28cm in length mentioned earlier. 0 1 2 3 4 5 RESULTS PREYED TAXA COMPOSITION OF THE DIET Vipers over 28cm long The total of 95 ingested remains - ingested taxa obtained and identified shows a considerably high degree of invertebrates present in the diet of these f:� ingested biomass ophidians (83.2% of the identified prey), particulary Orthoptera (78.9%). Vertebrate remains were common, FIG. I. Percent frequency of the preyed taxa (black columns) amounting to 16.8% of the total number of prey; these and their relative biomass percentages (striped columns) in consisted of 6.3% Lacertidae (Reptilia, Sauria), 7.3% Vursinii in the studied environment: 1 = Lacertidae, Reptilia; 2 juvenile Microtidae (Mammalia, Rodentia), and 3.1% = Microtidae, Mammalia; 3 = Motacillidae, Aves; 4 = nestling Motacillidae (Aves, Passeriformes) (Table 1, Orthoptera, Insecta; 5 = Other Prey (Coleoptera, Insecta; Fig. 1). Opilionidae, Arachnida). These data are referred to specimens of more than 28 cm. in overall length. Longer than 28 cm. N=43 n %n n n' n/n' Po darcis muralis 6 6.3 Po darcis muralis 6 6 1 Microtidae 7 7.3 Microtidae 7 4 1.7 Anthus s. spinoletta 3 3.1 Anthus s. spinoletta 3 1 3 Orthoptera Tettigonidae 6 6.3 Orthoptera 75 29 2.6 Orthopter<i Acrididae 46 48.4 Coleoptera 1 1 1 Orthoptera undet. 23 24.2 Opilionidae 3 2 1.5 Coleoptera undet. 1 1.2 Opilionidae undet. 3 3.2 TABLE 2. Distribution of the total number of prey (n = 95) in relation to the total number of stomachs (n' = 43). 95 100 (Vipers >28 cm. in total length.) Shorter than 28 cm. N=7 n n %n Podarcis muralis 2 Rodents undet. 3 Po darcis muralis 1 7.2 Orthoptera undet. 29 Orthoptera undet. 10 71.4 Chilopoda undet. 1 Silphiidae (larva) 1 7.2 Coleoptera undet. 2 Opilionidae undet. 2 14.2 Undetermined Animal Residues 7 14 100 TABLE 3. List of prey residues obtained from 34 excreta of vipers > 28 cm. in length. n is the total number of the excreta in TABLE I. List of prey obtained fro m the gastrointestinal tract which a single kind of prey has been discovered.