Microhabitat Selection of the Western Green Lizard Lacerta Bilineata Massimiliano Luppi1, 2, *, Augusto Gentilli2, Giuseppe Bogl
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Natural History Sciences. Atti Soc. it. Sci. nat. Museo civ. Stor. nat. Milano, 7 (2): 3-10, 2020 DOI: 10.4081/nhs.2020.451 Microhabitat selection of the Western green lizard Lacerta bilineata Massimiliano Luppi1, 2, *, Augusto Gentilli2, Giuseppe Bogliani2 Abstract - We examined the characteristics of microhabitats INTRODUCTION selected by Western green lizards, Lacerta bilineata. Model selection The traditional agricultural environment has been was carried out with the Information-theoretic approach that focuses on the estimation of effect size and measures of its precision. Our modified in recent decades in order to enhance produc- results show that the Western green lizard selects positively sites with tion. This model of development has led to the reduc- good shrub cover, necessary as shelter, while it avoids areas with bare tion of natural areas and especially ecotonal areas and soil where there are no refuges. Additionally, lizards showed a posi- hedgerows that may act as wildlife habitat and ecological tive selection of rocks (located exclusively in artificial riverbanks) that corridors between natural and semi-natural areas. Habi- represent a suitable habitat for thermoregulation and sheltering. The tat fragmentation is one of the biggest problems for the results of our work, and particularly the negative effects of bare soil and the positive effects of shrub cover, confirm the need to restore the net- conservation of biodiversity, especially for animal groups work of hedgerows and other linear elements in cultivated landscapes such as reptiles, which have reduced mobility (Rubio & in order to create suitable areas for L. bilineata. Carrascal, 1994). The Western green lizard (Lacerta bilineata) is a large Key words: habitat, information-theoretic methods, Italy, lizard, lizard (adult total length: 30-45 cm) that occupies the model averaging. Northern part of the Iberian Peninsula, France, Switzer- land, West Germany and Italy (Elbing et al., 1997; Corti Riassunto - Selezione del microhabitat del ramarro Lacerta bili- & Lo Cascio, 2002; Schiavo & Venchi, 2006). It lives in neata. open habitats and is widespread in the uncultivated edges Abbiamo esaminato le caratteristiche del microhabitat selezionate of woods and fields, along irrigation channels and roads dal ramarro, Lacerta bilineata. La selezione dei modelli è stata fatta con l’approccio Information-theoretic che si focalizza sulla stima del (Barbieri & Gentilli, 2002; Schiavo & Venchi, 2006; valore degli effetti e sulla misura della loro precisione. I nostri risultati Meek, 2014; Pernat et al., 2017). mostrano che il ramarro seleziona positivamente i siti con una buona Lacerta bilineata appeared to be still well distributed copertura arbustiva, necessaria come riparo, mentre evita le aree con in the lowland areas of Northern Italy until a few dec- suolo nudo dove non ci sono rifugi. Inoltre, i ramarri mostrano una ades ago, when it was abundant (Scali & Schiavo, 2004; selezione positiva delle rocce (localizzate esclusivamente nelle sponde Schiavo & Venchi, 2006). In recent years, however, the fluviali artificiali) che rappresentano un habitat adatto per la termore- golazione e come riparo. I risultati del nostro lavoro, e in particolare status of the species has become quite different because l’effetto negativo del suolo nudo e l’effetto positivo della copertura of the homogenization of the countryside, intensive cul- arbustiva, confermano la necessità di ristabilire una rete di siepi ed altri tivation and the destruction of hedgerows. In addition, elementi lineari del paesaggio coltivato in modo da creare aree adatte the use of pesticides has greatly reduced insect abun- per L. bilineata. dance and thus its primary source of food. The Western Parole chiave: approccio information-theoretic, habitat, Italia, green lizard is now locally threatened and the conversion lucertola, model averaging. of traditional agricultural habitats to intensive methods of farming is causing local population declines (Scali & Schiavo, 2004; Schiavo & Venchi, 2006). Moreover, 1 Via Pionnio 38, 27022 Casorate Primo (PV), Italia. 2 Dipartimento di Scienze della Terra e dell’Ambiente, the requirements of this species coincide with those of Università degli Studi di Pavia, Via Ferrata 9, 27100 Pavia, Italia. several other species typical of ecotones and, therefore, E-mail: [email protected], the Western green lizard might serve as an “umbrella [email protected] species” for many other taxa, playing a key role in pro- tecting these sensitive areas of transition. The species is * Corresponding author: [email protected] listed on appendix II (strictly protected fauna species) © 2020 Massimiliano Luppi, Augusto Gentilli, of the Bern Convention (Council of Europe, 1979) as L. Giuseppe Bogliani viridis and is considered of least concern (LC; popula- tion trend: decreasing) in the IUCN Red List of Threat- Received: 29 March 2020 ened Species (Pérez-Mellado et al., 2009). In Europe Accepted for publication: 10 July 2020 an important legal instrument of conservation is the EU Online publication: 28 October 2020 Habitats Directive (Council of Europe, 1992); L. bilineta 4 MASSIMILIANO LUPPI, Augusto GENTILLI, GIUSEPPE BOGLIANI (as L. viridis) is inserted in Annex IV (species in need of The area has a high environmental heterogeneity and strict protection). To ensure a favourable conservation includes hygro-mesophilic woods dominated by the pres- status, Member States shall take the required measures ence of oak (Quercus robur) with a rich undergrowth (Pru- to establish a system of strict protection, prohibiting all nus padus, Ulmus minor, Crataegus monogyna, Cornus forms of deliberate disturbance, capture or killing of sanguinea, Ligustrum vulgare), hybrid poplar plantations, specimens of these species in the wild and avoiding de- wetlands (Salix spp., Alnus glutinosa), and open areas terioration or destruction of their habitat. Nevertheless, characterized by a low value of shrub cover and a high val- few resources are invested in monitoring the status of ue of short herbaceous cover. Along a stretch of the bank species and habitats and in the absence of reliable data, of the River Ticino included in our study area, there is an it will be impossible to assess the impact of conservation artificial embankment consisting of large boulders; among measures. Therefore, studies on the ecology and status the rocks a shrub vegetation has developed, which consists of these species are essential. predominantly of bushes of Salix alba and Rubus spp.. The few remaining natural areas in the plains of Northern Italy, mostly limited to floodplains, offer a unique refuge for many animal species, including the Sampling methods Western green lizard, which find a suitable habitat along The study was conducted from July to October 2009, the riverbanks. The goal of this study was to collect data after the breeding season of the Western green lizard. Dur- on microhabitat selection by the Western green lizard in a ing this period, the activity pattern of lizards and habitat river floodplain in North-western Italy, in order to obtain characteristics were homogenous. We selected, inside our essential knowledge for developing appropriate manage- study area, most of the suitable habitats; then, in those ment strategies. Since the species is found in a variety of areas, we established a sampling path (length 2574 m) habitats, our aim was not to describe its general habitat, along dirt roads. We walked the sampling path on days but to highlight the microhabitat elements determining with favourable weather conditions, avoiding those with its presence, weighing all available microhabitats occur- uniform cloud cover and/or rain. Surveys were conducted ring in the study area. twice a week, covering a time band between 09:00 and 18:00 h CET. When we detected an unmarked adult in exposed positions, we captured it by noosing (Blomberg MATERIALS AND METHODS & Shine, 2006). After capture, each individual was measured (snout- Study Area vent length, SVL), photographed (ventral photo) and im- The study was carried out in a natural area approxi- mediately released at the exact location of capture. Each mately 100 ha wide and located 70 m a.s.l., in the central lizard was also individually marked by a unique colour part of the floodplain of the Ticino Regional Park (Fig. code with acrylic paint on the dorsum for temporary iden- 1; 45°16’25”N; 8°59’05”E), in the municipality of Motta tification (Rubio & Carrascal, 1994; Martín & Salvador, Visconti (Lombardy, North-western Italy). The climate of 1995; Blomberg & Shine, 2006). We observed an average this area can be characterized as continental with a mean duration of the marking of three weeks. This technique temperature of approximately 13°C. The average annual allowed long-distance identification and reduced the need rainfall is about 700 mm and rain occur mainly during of recapture (Rubio & Carrascal, 1994). Ventral photos spring and autumn. The coldest month (January) has tem- were used to identify lizards individually using a photo- perature ranging from 0 to 3°C, while the warmest one identification software, I³S Classic (Interactive Individual (July) ranges between 22-24°C (Pilon, 2004). Identification System - vers. 2.0, available at http://www. reijns.com/i3s) (Speed et al., 2007; Van Tienhoven et al., 2007). Photo-identification uses the arrangement of scales of the chinstrap as natural marks (Sacchi et al., 2010); this arrangement does not change