Umbruch 10.01.2007 10:18 Uhr Seite 131 ECOTROPICA 12: 131–139, 2006 © Society for Tropical Ecology MOVEMENT DISTANCES OF FIVE RODENT AND TWO MARSUPIAL SPECIES IN FOREST FRAGMENTS OF THE COASTAL ATLANTIC RAINFOREST, BRAZIL Thomas Püttker 1,Yvonne Meyer-Lucht 1 & Simone Sommer 1,2 1 Dept. Animal Ecology & Conservation, Biozentrum Grindel, University of Hamburg, Martin-Luther-King-Platz 3, D - 20146 Hamburg, Germany 2 present address: Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Strasse 17, D-10315 Berlin, Germany Abstract. Movement distances provide information on diverse population biological parameters and are essential in under- standing the ecology of a species. Mean distances moved between successive captures (SD), distribution of movement distances, and the mean maximum distances moved (MMDM) were investigated in five rodent and two marsupial species in forest fragments of the coastal Atlantic rainforest (Mata Atlântica) in the state of São Paulo, Brazil. The investigated species were the rodents Akodon montensis (Thomas, 1902), Oligoryzomys nigripes (Olfers, 1818), Delomys sublineatus (Thomas, 1903), Oryzomys russatus (Wagner, 1848), and Thaptomys nigrita (Lichtenstein, 1829), and the marsupials Marmosops incanus (Lund 1840), and Gracilinanus microtarsus (Wagner, 1842). Akodon montensis differed significantly from all other species and moved the lowest SD and MMDM. The marsupials differed significantly from most of the rodents and moved the largest SDs. All species showed the highest frequency of movements in a distance class of 0–20 m. Differences between sexes in SD was detected for O. nigripes, O. russatus, and G. microtarsus, males moving significantly longer distances than females. The different study sites had no influence on SD in any of the investigated species. Only the males of G. microtarsus showed a seasonal variation in SD, moving longer distances during reproductive activity. Accepted 15 August 2006. Key words: distance moved between successive captures, marsupials, Mata Atlântica, rodents, small mammals. INTRODUCTION of a population, such as density estimates, as well as to understand its genetic structure (Mendel & Vieira Movements of animals are an important element in 2003). their ecology (Turchin 1991, Diffendorfer et al. 1995, The use of distances moved between successive Slade & Russell 1998) and provide essential infor- mation about the spatial distribution of species (Stapp captures instead of area calculations like minimum & Van Horne 1997). Movement patterns and dis- convex polygons has several advantages. Movement tances are related to several aspects of the ecology of distances are comparatively easy to assess, easy to cal- a species, like genetic structure, feeding habits, food culate, and can be used even for individuals with cap- availability, mating systems, and reduction to expo- ture histories too brief for models (Stickel 1954, Slade sure to predators (Slade & Swihart 1983, Austad & & Swihart 1983). Studies have indicated that distance Sunquist 1986, Sunquist et al. 1987, Barnum et al. measurements are correlated with home range size 1992, Stapp & Van Horne 1997, Roche et al. 1999) (Faust et al. 1971, Slade & Russell 1998). They pro- Moreover, movements are associated with the social vide an average index of the home range for the spe- organization and population dynamics of a species cies (Davis 1953) and can be used for comparison be- (Slade & Swihart 1983, Bowers et al. 1996, Mendel tween groups within a species (e.g., age- or sex-spe- & Vieira 2003, Bergallo & Magnusson 2004). The cific analyses, Slade & Russell 1998) or between dif- knowledge of distances moved by different species is ferent species (Gentile & Cerqueira 1995). Never- necessary to calculate basic parameters of the ecology theless, using trapping distances as an index for spatial use also has some disadvantages. Some individuals might preferentially be caught in one trap or make a e-mail: [email protected] trap unattractive for others. The capture probabilities 131 Umbruch 10.01.2007 10:18 Uhr Seite 132 PÜTTKER ET AL. between individuals or species might differ because scape, which is dominated by anthropogenic habitat of different behavioral responses or heterogeneity due (agricultural fields: 33 %; areas with rural buildings to age or sex, or to time effects (White et al. 1982). or urban areas: 15 %; vegetation in early stages of Therefore, the use of distances between successive cap- regeneration: 10 %; pine and eucalyptus plantations: tures to reflect movements of species is not directly 7 %; others: 4 %). The Morro Grande Reserve also comparable to home range size data obtained by di- consists mainly of secondary forest. Only a minor part rect measurements (e.g., radio-tracking). of the reserve provides mature forest. The coastal Atlantic rainforest of Brazil (Mata Animals were captured in five forest fragments of Atlântica) is one of the most diverse but at the same different sizes (14–175 ha), and in the Morro Grande time one of the most threatened environments in the Reserve (10 700 ha). All sites are of secondary growth world (Myers et al. 2000, Galindo-Leal & de Gusmão forest and between 50 and 80 years of age (Godoy Câmara 2003). Only about 8% of its original extent Teixeira 2005). Two fragments are about 14 ha (S1, still remains and it harbors a great variety of small S2), another two fragments are approximately twice mammal species (Emmons & Feer 1997, Stevens & this size (30 ha; S3, S4), and the fifth fragment (S5) Husband 1998) with an overall high percentage of en- is the largest, embracing 175 ha of secondary forest. demic species (Fonseca et al. 1996, Stevens & Hus- The control site (CS) also consists of secondary for- band 1998). For most Mata Atlântica species infor- est and is part of the Morro Grande Reserve. A more mation about distances moved is limited. detailed description of the study area can be found During a capture-recapture study, in the course in Pardini et al. (2005). of a study on population dynamics of small mammals Data collection. A regular trapping grid of one hun- inhabiting the coastal Atlantic rainforest, we investi- dred trap stations 20 m apart was established in all gated the distances moved between successive captures six study sites. The grid consisted of 10 x 10 trap (SD, Murie & Murie 1931), the distribution of move- stations, except in two sites where the shape of the ment distances, and the mean maximum distance fragments and the general objective of placing all traps moved (MMDM, Wilson & Anderson 1985) of sev- within the forest required that the trapping grid be en small mammal species in a trapping grid. We fo- slightly modified. Two live-traps (H. B. Sherman cussed on the differences in movement length (SD, Traps Inc., Tallahassee, USA) were set at each trap sta- MMDM) between species and further investigated tion, one small (23 x 9 x 8 cm) and one large (38 x differences in SD between gender, study sites, and 11 x 10 cm). One of the traps was set on the ground, capture sessions. and the other at about 1.0 to 1.5 m above the ground, alternating the positions of small and large traps be- METHODS tween trap stations. Study area. The study was conducted in the region of Data were collected during five trapping sessions Caucaia do Alto (23°40´S, 47°01´W), situated in the in each of the study sites from July 2003 to March municipalities of Cotia and Ibiúna, São Paulo state, 2005 (1st session: 23.07.–19.09.2003, 2nd session: about 80 km south-west of the city of São Paulo, Bra- 27.09.– 7.11.2003, 3rd session: 4.03.–7.04.2004, 4th zil, in a transition zone between dense ombrophilous session: 18.05.–26.06.2004, 5th session: 27.01.–3. forest and semi-deciduous forest classified as “Lower 03.2005). Each trapping session consisted of six nights Montane Atlantic rainforest” (Oliveira-Filho & Fontes of capture, for a total of 6000 trap-nights per study 2000). The altitude varies between 800 and 1100 m site. Traps were baited with banana and a mixture of (Ross & Moroz 1997). Monthly mean temperature peanut butter, oat, and sardines, left open for the night, ranges from a minimum of 11°C to a maximum of checked every morning and rebaited if necessary. Cap- 27°C. Annual precipitation equals 1300–1400 mm tured animals were anesthetized (Forene®, Abbott and fluctuates seasonally with the driest and coldest GmbH, Wiesbaden, Germany) for 1–2 minutes and months between April and August. marked individually by numbered ear tags (Fish and The area includes a fragmented area and a large, small animal tag size 1, National Band and Tag Co., lower mountainous Atlantic rainforest area (Morro Newport, Kentucky, USA). In addition to sexing and Grande Reserve). The fragmented area consists of sec- weighing, the length of their tibia was measured to ondary forest fragments embedded in an agricultural the nearest 0.5 mm. All individuals were released sub- landscape. Secondary forest covers 31% of the land- sequently at their respective trapping location. 132 Umbruch 10.01.2007 10:18 Uhr Seite 133 MOVEMENT DISTANCES IN SMALL MAMMALS, BRAZIL Statistical analysis. All individuals captured more than as for the marsupials Marmosops incanus (Lund, 1840) once were included in the calculations of SD. The SD and Gracilinanus microtarsus (Wagner, 1842). Only was compared between species, sexes, study sites, and A. montensis and M. incanus were captured at all six between sessions (seasonal variation). To investigate study sites and in every capture session. The didelphid the distribution of movement distances, the distances marsupials Didelphis aurita (Wied-Neuwied, 1826), were grouped into classes. The maximum distance Monodelphis americana (Müller, 1776), and Micou- moved was calculated for each individual at each cap- reus paraguayanus (Oken, 1816), and the rodents Ju- ture session, and the mean maximum distance moved liomys pictipes (Osgood, 1933), Oryzomys angouya (Fi- (MMDM) was calculated for each species.