A Note on Terrestrial Activity and Feeding in the Spectacled Salamander, Salamandrina Terdigitata (Urodela, Salamandridae)
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A note on terrestrial activity and feeding in the Spectacled salamander, Salamandrina terdigitata (Urodela, Salamandridae) CARLO UTZERP , DAMIANO ANTONELLI2 and CLAUDIO ANGELINP* I University "La Sapienza", Dip.to di Biol. Animale e dell'Uomo, Viale dell'Universita 32, 1-00185 Roma RM, Italy 2 Strada dei Benedettini 10, 1-05100 Terni TR, Italy * Corresponding author: email: [email protected] ABSTRACT — At a low elevation site (ca 200 m a.s.I.) in central Italy, the Spectacled salamander was observed to be active mostly in the open ground between 18:00 and 24:00 hrs, while daytime activity was seldom recorded. Activity was positively correlated with air temperature, but the internal temperature of salamanders was correlated to substrate temperature. Thirteen taxa of terrestrial arthropods were recorded from faecal pellets, the greater part of which (36%) was represented by Acarina. HE Spectacled salamander, Salamandrina house on the outskirts of Terni, Umbria, central Tterdigitata, is a terrestrial urodele endemic to Italy, at about 200 m a.s.l., and was used by S. Italy. Although described more than two centuries terdigitata as an oviposition site. Occasional ago, very little information has so far been observations were also carried out at some published on its ecology. The species is reported to breeding sites in the Lepini mountains, Latium, be active by night, or sometimes during daylight central Italy. on cool, humid or rainy days (Ramorino, 1863; We recorded the number of salamanders active Lessona, 1868; Lanza, 1983; Bruno, 1973, 1983; in the open while covering a fixed 50-metre Zagaglioni, 1978; Vanni, 1980; Barbieri, 1994; transect four times a night, between 18:00-21:00, Zuffi, 1999), but nothing is otherwise known of its 21:00-24:00, 24:00-03:00 and 03:00-06:00 hrs. daily activity cycle. Cherchi (1953) provided some In order to avoid disturbing the salamanders, we information on internal temperatures, and notes on did not record their ventral patterns — which are food consumption were published by Ramorino unique to individuals — and therefore cannot state (1863) and Vanni (1980). the precise number of individuals concerned. In the framework of an extensive investigation Internal (cloacal) temperatures of salamanders as on the population ecology of S. terdigitata in well as air temperatures were recorded by a digital central Italy, we collected some data on the thermocouple thermometer on llth December 1996, terrestrial activity of several specimens, which in between 22:30 and 23:40 hrs, with cloudy sky, light of the deficient knowledge on the ecology of discontinuous light rain and no wind. For internal this species we believe are worth publishing. temperature, a probe of 0.5 mm in diameter was used. The humidity variation was given by the MATERIALS AND METHODS Meteorological Station 'Federico Cesi', Terni. We carried out field observations during five A few individuals were kept singularly in small nights between 4th November 1996 and 3rd terrariums (without food) for a few days and their January 1997, in open ground on clay-based soil faecal pellets (n = 24) collected for the purposes of near a shallow well. This was excavated in 1982 identifying food remains. These were preserved in and has since recovered to semi-natural 70% aethylether and examined subsequently with conditions. The well is located in the garden of a the aid of optical binoculars. Number 90 - Herpetological Bulletin [2004] 27 Activity and feeding in the Spectacled salamander and 15:00 hrs, with clear Taxa This note References skies and an air temperature of 11°C. However, at the Annelida Vanni, 1980; Bruno, 1973, 1983 site in Umbria, except for Gastropoda Vanni, 1980; Bruno, 1983 ovipositing females — which spent one or more Copepoda Bruno, 1973, 1983 days submerged in water — Isopoda Vanni, 1980; Bruno, 1973, 1983 salamanders were only Aracnida Vanni, 1980; Bruno, 1973 active at night, and always on moist ground. In total Pseudoscorpiones Vanni, 1980 we made 230 observation Aranee Bruno, 1983 records. Salamanders were Acarina Vanni, 1980 active mostly between 18:00-24:00 hrs and there Mtriapoda Vanni, 1980; Bruno, 1973, 1983 was a positive correlation Juliformes Vanni, 1980 between time of activity Collembola Vanni, 1980 and average air temperature (Spearman coefficient rs = Orthoptera Ramorino, 1863; Vanni, 1980 1.00; p = 0.00), and a Notonectidae Ramorino, 1863 negative — but not Coleoptera Vanni, 1980; Bruno, 1973, 1983 significant correlation between activity and Staphylinidae average air humidity (r = Carabidae 0.80; p = 0.20) (Fig. 1). Curculionidae Internal temperature The Anthicidae cloacal temperatures of 12 various larvae Ramorino, 1863 active salamanders ranged Diptera Vanni: 1980; Bruno, 1973, 1983 from 7.6°C to 9.8°C (mean ± SE = 8.8 ± 0.2°C). All Hymenoptera Vanni, 1980 salamanders showed an Formicidae internal temperature lower than air temperature, which Table 1. Taxa identified in faecal pellets of S. te►digitata. was constant at 10°C throughout the observation period (average At°± SE = -1.2 ± 0.2°C; range Since no pattern characteristics are available to between -2.4 and -0.2°C), and was either slightly distinguish between males and females — although higher or lower than substrate temperature on average males are smaller and more slender (average At° ± SE = -0.3 ± 0.2°C; range between - than females and possess a relatively larger head 1.2 and 0.4°C), to which it was correlated 0.66; p <0.02; n = 12) (Fig. 2). On one (Vanni, 1980; Angelini et al., 2001) — we did not (rSpearman occasion in the Lepini Mountains we recorded a attempt identification of the sexes, and herewith salamander walking on snow at 11°C, but we did treat them collectively. not record its internal temperature. RESULTS Food — Among the undigested food from faecal Night activity — At the oviposition sites in the pellets, we identified 13 taxa of terrestrial Lepini Mountains, we occasionally found arthropods (Table 1). We also identified a salamanders active on the ground between 11:00 fragment of a conch of a pulmonate mollusc, as 28 Herpetological Bulletin [2004] - Number 90 Activity and feeding in the Spectacled salamander Cherchi (1953) conducted laboratory experiments to determine the maximum and N 0/0 Taxa minimum temperatures tolerated by S. terdigitata by keeping specimens at variable temperatures Isopoda 2 10.5 until their eventual death. He fixed at —17°C and Pseudoscorpiones 1 5.3 32-35°C, respectively, the minimum and maximum critical temperatures relative to the 3 15.8 Aranee animals' survival. He also recorded daily cloacal Acarina 6 31.6 and ambient (laboratory) temperatures, but not substrate temperature, of three specimens in the Juliformes 1 5.3 course of a month, and reported that the Staphylinidae 1 5.3 salamanders' internal temperature averaged lower than air temperature. Our findings (Fig. 2) agree to Anthicidae 1 5.3 those of Cherchi (1953), but the significant, Diptera 1 5.3 positive correlation between substrate and salamander cloacal temperatures suggests that Formicidae 3 15.8 substrate temperature most probably influences the salamanders' activity in the field. Total 19 100.2 With regard to diet, apparently only Ramorino (1863) and Vanni (1980) have provided original data Table 2. Diet composition of S. terdigitata, based on food based on the analysis of stomach content of adult remains from 14 faecal pellets. salamanders. In the literature there are further reports of food records in S. terdigitata (Lessona, well as various items alien to the salamander diet 1868; De Betta, 1874; Angel, 1949; Thorn, 1969; such as glass fragments, seeds, and small pieces of Hvass, 1972; Lanza, 1983, 1988; Bogliani & wood and grass, probably accidentally ingested Barbieri, 1986; Di Tizio, 1986; Corsetti, 1994; Zuffi, together with prey. Some of the remaining 1999) but these probably refer to previous papers. materials, even though apparently of animal Our data add some previously unreported items to origin, could not be identified. Composition of the the food spectrum of S. terdigitata, and this is diet is presented in Table 2. Only once in the field particularly relevant because they were obtained did we observe a salamander quickly and from a very small sample (24 faecal pellets) using repeatedly thrusting its tongue out and in as if non-invasive methods. This suggests that the feeding, but we were not able to identify any prey. Spectacled salamander may feed on an even wider range of prey and that more information should be DISCUSSION obtainable in the future from larger faecal samples At the Umbria site, most salamanders were active and without sacrificing animals. The analysis of during the first half of the night and only a very few faecal pellets may preclude identification of prey individuals after midnight in the open ground. The species that typically leave behind only a few usual increase of air humidity after sunset should undigested fragments (e.g. earthworms and some be favourable to salamanders, while temperature insect larvae). However, unidentified prey remains decrease might cause the marked activity decline have also been recorded from dissected stomachs recorded between 24:00-06:00 hrs. However, it is (Vanni, 1980). possible that prey in the area was fairly abundant, Ramorino (1863) and Bruno (1973, 1983) gave and a few hours feeding were all that may have information on aquatic prey items (tab. 1), which been necessary to sustain daily activity. considering the strictly terrestrial habits of S. Number 90 - Herpetological Bulletin [2004] 29 Activity and feeding In the Spectacled salamander pu .. — — E 43.5% o 40.9% , -., _ C) E ( % re tu 0. idity era p hum 8? fp tern 1121% ti a 5.6% o c n . o 18-21 21-24 24-:3 3-6 time intervals (24 hours) Figure 1 Relations of number of active S.