Benício_etal_Microhabitat_selection_Ameiva_ameiva:HERPETOZOA.qxd 12.02.2019 14:53 Seite 1 heRPetozoa 31 (3/4): 211 - 218 211 Wien, 28. Februar 2019 microhabitat selection of Ameiva ameiva (Linnaeus , 1758), in the Brazilian Pantanal (squamata: sauria: teiidae) mikrohabitatwahl von Ameiva ameiva (Linnaeus , 1758) im brasilianischen Pantanal (squamata: sauria: teiidae) RoniLdo a. B eníCio & z aida oRteGa & aBRaham menCía & d anieL Cunha Passos KuRzFassunG die autoren untersuchten den einfluß einiger umweltparameter auf die mikrohabitatwahl von Ameiva amei - va (Linnaeus , 1758) im brasilianischen Pantanal, einem Lebensraum mit markantem Wechsel von Überflutung und trockenfallen. die analyse der mikrohabitatwahl erfolgte im september mittels Ressourcenauswahlfunktion (RsF) und Bedingter Logistischer Regression (CLR) an neunundzwanzig adulten individuen von of A. ameiva . die mit - tlere temperatur an den aufenthaltsorten betrug 36 °C (spannweite: 27 °C – 51 °C; standardabweichung: 6,8 °C). im Verlauf der tagesaktivität waren die temperaturen des substrats auf dem A. ameiva beobachtet wurde, abwech - selnd sowohl bei sehr hohen als auch deutlich niedrigeren Werten gehäuft. das CLR modell zeigte, daß keiner der untersuchten umweltparameter substrattemperatur, substrattyp und sonnenexposition die Wahrscheinlichkeit des Vorkommens von A. ameiva an einem bestimmten aufenthaltsort signifikant beeinflußte (zugehörige P-Werte: 0,11; 0,69 und 0,87), wobei bei der sonnenexposition die Qualitäten volle Besonnung, schatten und halbschatten und beim substrattyp Gras, Laubstreu und blanker Boden unterschieden wurden. die ergebnisse legen nahe, daß A. ameiva zumindest während der trockenzeit im brasilianischen Pantanal kein mikrohabitat-spezialist ist. aBstRaCt the authors studied the influence of three environmental traits on the microhabitat selection of Ameiva amei - va (Linnaeus , 1758), in the Brazilian Pantanal, an environment with a marked effect of seasonality, i.e., alternating periods of flooding and falling dry. microhabitat selection was assessed in the dry season using a Resource selection Function (RsF) and Conditional Logistic Regression (CLR) analysis. twenty-nine adult individuals of A. ameiva were observed. the average temperature in places where individuals occurred was 36 °C (ranging from 27 °C to 51 °C; sd = 6.8 °C). the pattern of the temperature of the substrate on which A. ameiva was observed showed peaks, occurring alternatively either at very high but also milder temperatures along its daily activity period. the CLR model revealed that none of the studied environmental variables (substrate temperature, type of substrate or sun exposure) significantly affected the probability of occurrence of Ameiva lizards at a particular point ( P = 0.11, P = 0.69, P = 0.87, respectively). Regarding the sun exposure situation the qualities full sun, shade and filtered sun were distinguished, the substrate type comprised the parameter values grass, leaflitter and exposed soil. the results suggest that A. ameiva is not a microhabitat specialist, at least during the dry season in the Pantanal of Brazil. KeY WoRds Reptilia: squamata: sauria: teiidae; Ameiva ameiva ; ecology, behavior; foraging activity, microhabitat use, occurrence, substrate, wetlands, Pantanal, Brazil intRoduCtion Ameiva ameiva (Linnaeus , 1758), is a (VanzoLini et al. 1980) and occurring in medium-sized (snout-vent length up to 174 almost all Brazilian territory ( aViLa -P iRes mm after Vitt & C oLLi 1994 ; Fig. 1) ground- 1995). across its distribution, this species in - dwelling lizard that spends a large amount of habits a variety of environments ( Vitt & its activity period moving, a typical pattern CoLLi 1994), such as forest edges and open of wide/ active foragers ( RoCha et al. 2009). areas within rainforests ( CRuz -n eto & it has a vast geographical distribution, living GoRdo 1996; L ima et al. 2001), seasonally mainly in open areas of south america dry forests ( Vitt 1995; s aLes et al. 2011a), Benício_etal_Microhabitat_selection_Ameiva_ameiva:HERPETOZOA.qxd 12.02.2019 14:53 Seite 2 212 R. a. BeníCio & z. oRteGa & a. menCía & d. C. P assos savannas ( CoLLi 1991) and coastal shrub - microhabitat use of several populations lands ( zaLuaR & R oCha 2000) as well as of A. ameiva was studied at different human disturbed areas ( saRtoRius et al. Brazilian biomes ( saRtoRius et al. 1999; 1999). Ameiva ameiva mainly feeds on inver - zaLuaR & R oCha 2000; s aLes et al. 2011a). tebrates (Vi tt & C oLLi 1994; z aLuaR & however, there is still a lack of knowledge RoCha 2000, s aLes et al. 2011b, FReitas et about A. ameiva lizards from the Pantanal, an al. 2012), despite sporadically including some area of flooded grasslands from western vertebrates and plant material in the diet Brazil ( JunK & d e Cunha 2005). Widely (RoCha & V RCiBRadiC 1998; saLes et al. distributed species often vary geographically 2010; moRaes & s antos 2012; siLVa et al. in the microhabitat use, and it is important to 2013). these lizards are mainly diurnal and study this intraspecific variability since it is concentrate their activity within the warmer related to niche specialization, evolution and hours of the day, usually between 10:00 h and adaptability to environmental changes ( BoR- 14:00 h ( Vitt & C oLLi 1994; saRtoRius et al. zee et al. 2016; BaRs -C LoseL et al. 2017). 1999; zaLuaR & R oCha 2000; saLes et al. thus, the authors’ present study aimed to 2011a). their life-history traits vary along the evaluate which environmental traits influ - broad geographical range, but reproduction ence the occurrence of A. ameiva in the Pan - begins and tends to be more intense during tanal, an environment with a marked effect of the wet period ( Vitt 1982; C oLLi 1991; V itt seasonality, i.e., alternating periods of flood - & C oLLi 1994; R oCha 2008). ing and falling dry ( meRCante et al. 2011). mateRiaLs and methods the study was conducted in the Pan - location were registered, measured with a tanal region of miranda-abrobal, near the laser infrared thermometer (Benetech ® Base de estudos do Pantanal (BeP) of the Gs320, precision 0.1 °C) from one meter Federal university of mato Grosso do sul maintaining a constant distance, to maxi - (Corumbá, mato Groso do sul, Brazil) at mize the comparability of the measurements. 19°34’37” s, 57°00’42” W, in the dry sea - in addition, the authors recorded the type of son, september 2017. the Pantanal domain substrate (‘grass’, ‘leaf litter’ and ‘exposed is embedded in one of the most distinct eco - soil’) and the sun exposure (‘full sun’, regions concerning orography: the flooded ‘shade’ and ‘filtered sun’) of the microhabi - grasslands and savannas ( PRado et al. 1992; tat where the individual was observed (= LouRiVaL et al. 2000). Located in the west - used point). to assess microhabitat selec - ern portion of the state of mato Grosso do tion, the same variables (t s, type of substrate sul, the Pantanal occupies approximately and sun exposure) were registered at four 71.500 km 2 of the state territory (FeRReiRa unused points related to each used point. et al. 2017). unused points were de fined one meter north, the Ameiva lizards were sampled south, west and east from each used point as within three consecutive days (september an objective criterion to standardize their 26-28) through active visual search ( CRumP location. these unused points represented & s Cott 1994) in the period from 07:00 h to the available microhabitats for each lizard in 17:00 h (local time) on two transects of one a given moment. Comparing environmental kilometer each, both in the surroundings of variables of the used and unused points the BeP. to avoid pseudo replication, each would allow for the study of the influence of transect was divided into parts, sampled the registered variables in the microhabitat sequentially in different days. in this way, selection of A. ameiva . each part of the transect was sampled only microhabitat selection was assessed once. the study was purely observational, using a Resource selection Function (RsF) without capture of any individual, to avoid (manLY et al. 2007). Resource selection animal stress. upon observation of a lizard, Functions calculate the odds ratio of an indi - the time of the day (hour in local time) and vidual to use a certain resource relative to its the substrate temperature (t s) of its exact availability in the environment. in the pres - Benício_etal_Microhabitat_selection_Ameiva_ameiva:HERPETOZOA.qxd 12.02.2019 14:53 Seite 3 microhabitat selection of Ameiva ameiva (Linnaeus , 1758) in the Brasilian Pantanal 213 Fig. 1: adult individual of Ameiva ameiva (L innaeus , 1758) , at the Base de estudos do Pantanal, Federal university of mato Grosso do sul, Corumbá, mato Grosso do sul, Brazil. abb. 1: adulte Ameiva ameiva (L innaeus , 1758) in der Base de estudos do Pantanal der universität von mato Grosso do sul, Corumbá, mato Grosso do sul, Brasilien. ent case, the resources are the microhabitat presence of the lizard in a certain microhab - explicative variables of interest: t s, type of itat (recorded as 1 for the used points and 0 substrate and sun exposure. solving RsFs for the four associated unused points). the by means of Generalized Linear models CLR was conditioned by the identity of (GLms) allows modeling the probability of each individual lizard, to guarantee that val - occurrence of the lizard, given several ex - ues of the explicative variables of each used plicative variables and their interactions. in microhabitat