Amphibian populations are declining on a global scale and although disease outbreaks are a commonly accepted hypothesis they are not the only one. My aims for my thesis were to study the home range of Leiopelma hamiltoni, to determine whether a photographic database could be used to individual identified them and monitor the health status of the population. Habitat loss is a possible cause. For this reason monitoring an animals' home range is a possible method to detect early impacts the population is facing. By tracking 12 L. hamiltoni within a 12 m x 6 m grid on Maud Island, it was shown that the home range size can vary from 0.5 m2 to 25 m2 based on the minimum convex polygon method. However, to track multiple individuals it is important to be able to distinguish among frogs. The commonly used methods of identification, such as toe clipping, pose potentially detrimental effects. Therefore, non-invasive methods based on natural markings need to be established. Through the use of the dark pigmented patterns found on the skin of L. hamiltoni individuals can be identified on recapture with a mean accuracy of 93%. By developing a database to maintain the photographs used for individual identification, the database can also be used to monitor the status of the population. During 2003 numerous L. hamiltoni were observed with denuded patches predominantly on the facial region. By monitoring five individuals within the captive facility at the University of Canterbury it was discovered that frogs appear to be able to cure themselves. Through researching the home range requirements and developing a photographic database to monitor the population status of L. hamiltoni, it will aid in the management of ensuring the long-term survival of this archaic species of frog.

Aspectos da ecologia populacional do tuco-tuco-das-dunas (Ctenomys flamarioni) foram estudados na região costeira da Estação Ecológica do Taim, com o objetivo de determinar características ecológicas, como a estrutura populacional e o tamanho e a forma da área de vida (home-range), utilizando a radiotelemetria numa população de Ctenomys flamarioni. O estudo foi desenvolvido entre dezembro de 2011 a março de 2013, foram realizadas 06 campanhas a cada trimestre de acordo com as estações sazonais com duração de quatro dias consecutivos. A extensão da área de estudo definida abrangeu uma área de 6 ha. O tamanho da área de vida foi calculado pelo software Biotas 2.0, utilizando o estimador de Kernel (95%) e o estimador MCP (100%). Foram capturados 56 indivíduos de Ctenomys flamarioni, 18 machos e 38 fêmeas. Foram realizadas 59 recapturas. A estimativa do tamanho populacional indicou uma pequena oscilação na taxa populacional entre as campanhas de amostragens sazonais. O valor da densidade demográfica média encontrada foi de 3,92 ± 0,5 indivíduos por hectare. No estudo de rádio-telemetria obteve-se 169 localizações dos indivíduos monitorados. Os resultados obtidos demonstraram uma nítida diferença entre estes dois métodos. O tamanho médio de área da vida obtido em Kernel (95%) foi de 1.860,3 m2 ± 832,0 para as fêmeas e 2.168,3 m2 ± 2.597,5 para os machos. Já os resultados obtidos pelo método MCP foram de 707,1 m2 ± 230,1 nos para as fêmeas e 3.334,5 m2 ± 2.632,1 para os indivíduos machos. A utilização da ferramenta de rádio-telemetria se mostrou uma grande aliada para responder algumas questões encontradas no programa de marcação e recaptura, como a taxa de deslocamento, aspectos comportamentais e mortalidade. / I studied aspects of population ecology of the Tuco-tuco of the dunes (Ctenomys flamarioni), such as population structure and home-range size and shape, in the coastal region of the Taim Ecological Station. The study was conducted from December 2011 to March 2013, in six campaigns of four consecutive days. Sampling was stratified along the annual seasons. My study site comprised a strip of sand dunes of 500 X 120 meters, totaling an area of 6 ha. I captured 56 individuals of Ctenomys flamarioni, 18 males and 38 females, and registered 59 recapture events. Population size estimates indicated short term population oscillations between seasons, but a long term equilibrium, with population sizes similar at the beginning and at the end of my study. The average population density was 3.92 ± 0.5 individuals per hectare. Using radio-telemetry, I obtained 169 locations. The results showed a clear difference between the two methods used to estimate home-range. The average home-range obtained with Kernel (95%) was 1860.3 ± 832.0 m2 for females and 2168.3 ± 2597.5 m2 for males. Home-ranges estimated by the MCP were 707.1 ± 230.1 m2 for females and 3334.5 ± 2632.1 m2 for males. The use of radio telemetry proved to be a great ally to answer some questions raised with mark-recapture analyses, such as, the rate of displacement, mortality and behavioral aspects.

Swamp rabbit and eastern cottontail populations have declined substantially in Illinois within the last half-century. Habitat loss and fragmentation, particularly of bottomland hardwood (BLH) forest, have left swamp rabbit populations patchily distributed along major rivers in the southern portion of the state. In addition, the decline of early-successional upland habitats due to changes in farming techniques have led to as much as 90% declines in cottontail populations in Illinois. Managers need information on basic vital rates and habitat use to conserve both species in southern Illinois; however, many questions regarding demography and behavior have not been investigated. My research examined the importance of several factors that may influence survival and habitat use among swamp rabbits and eastern cottontails. My specific research objectives were to 1) estimate seasonal and annual survival rates and identify primary mortality agents, 2) examine the influence of intrinsic factors and habitat variables on annual and seasonal 50% core area (CA) and 95% home range (HR) sizes, 3) assess differences in space use and habitat use by season, and 4) evaluate differences in space and habitat use between species for swamp rabbits and cottontails in BLH forests in southern Illinois. During December-March 2009-2013, I live-trapped and radiocollared adult swamp rabbits (>1.9 kg) and cottontails (>1.0 kg) at 7 BLH sites along the Cache River and Cypress Creek within the Cypress Creek National Wildlife Refuge in southern Illinois. I monitored rabbits for survival every 24-48 hr and estimated radiolocations by triangulation more than twice weekly during morning (0500-0900 hr), daytime (0900-1700 hr), and evening (1700-2400 hr) time periods on a rotating schedule. I delineated annual and seasonal 50% CA and 95% HR isopleths using kernel density estimators, comparing winter-spring (W/S; 21 Dec-19 Jun) and summer-fall (S/F; 20 Jun-21 Dec) seasons. During May-August 2012, I sampled microhabitat in 0.02-ha circular plots (3.5 plots/ha) randomly placed throughout home ranges of rabbits at each site. In ArcGIS, I classified macrohabitat patches into 1 of 4 cover types: agriculture, early-successional BLH (EBLH), mature BLH (MBLH), or upland. I also measured the distance from all radiolocations to the nearest patch of each cover type and the nearest river or creek. I modeled the influence of species, sex, and season on annual survival using parametric survival regression models. Then, I used the best model (based on AICc) to examine the influence of habitat covariates on survival. I also modeled the influence of habitat on annual and seasonal CA and HR sizes using generalized linear and generalized linear mixed effects models with AIC model selection. Finally, I estimated conspecific and heterospecific CA and HR overlap for swamp rabbits and cottontails, and examined differences between species in space and habitat use. I documented causes of mortality and estimated survival for 129 swamp rabbits and 75 cottontails during the period of study. Predation (71%) was the primary mortality agent for both species, followed by weather (9%) and hunter harvest (6%). Models with survival rates differing by species and season received the most support; swamp rabbits had higher estimated annual survival (0.37  0.05) than did cottontails (0.20  0.05), and survival for both species was lowest during the W/S season (βW/S=-2.28  0.46). None of the habitat covariates that I measured apparently influenced survival. Core areas and HRs were estimated for 60 swamp rabbits (SR; 34 M, 26 F) and 21 cottontails (CT; 10 M, 11 F) during the W/S season; of these, 57 swamp rabbits and 11 cottontails lived long enough to estimate S/F seasonal and annual home ranges. The average annual CA and HR for swamp rabbits were 2.49  1.42 ha and 11.60  5.81 ha, respectively. Cottontails had an average annual CA and HR size of 2.48  1.26 ha and 13.54  7.24 ha, respectively. Core areas and HRs for both species during the were larger during W/S than S/F (CA: βW/S=0.59  0.11, wi=1.0; HR: βW/S=0.53  0.11, wi=1.0). Seasonal CA sizes increased with decreasing proportions of woody ground cover within CAs (SR: βShrubs=-2.75  0.50, wi=1.0; CT: βShrubs=-2.30  0.74, wi=0.91). Few macrohabitat variables influenced space use for either species. The coefficient of variation in patch size within 1 km of study sites was positively associated with space use for both swamp rabbits (CA; β=0.01  0.004, wi=0.81; HR: β=0.01  0.003, wi=0.95) and cottontails (CA; β=0.02  0.01, wi=0.29; HR: β=0.02  0.01, wi=0.23); I did not detect significant differences between species in pairwise conspecific overlap within CAs or pairwise conspecific volume of intersection (VI) over the entire utilization distribution. Median conspecific CA overlap was higher during W/S than S/F, with mean CA overlap proportions of 0.20 ± 0.21 (range: 0−0.87) and 0.10 ± 0.18 (range: 0−0.73) respectively. Median conspecific VIs also differed between seasons, with mean pairwise VIs of 0.32 ± 0.19 (range: 0−0.77) during winter-spring and 0.19 ± 0.18 (range: 0−0.73) during S/F. Heterospecific CA overlap was 48% and 46% lower than conspecific overlap during W/S and S/F, respectively. Differences in habitat use between species were apparent. Swamp rabbits had HRs and CAs in areas with higher basal area compared to cottontails during both seasons (all U≥483, Z≥2.83, p≤0.005). Multivariate tests for both CAs and HRs indicated a significant effect of species on habitat use (CA: T2=0.58, F3, 71=13.70, p<0.001; HR: T2=0.24, F3, 71=5.80, p=0.001). During W/S, swamp rabbits had CAs and HRs composed of significantly higher proportions of EBLH (CA: F1, 73=16.46, p<0.001; HR: F1, 73=8.55, p=0.005) and MBLH (CA: F1, 73=17.99, p<0.001; HR: F1, 73=7.78, p<0.007). Swamp rabbits were located significantly closer to a permanent watercourse (F1, 79=24.18, p<0.001) than cottontails. Indeed, 95% of all swamp rabbit radiolocations were ≤332.0 m away from a permanent watercourse (mean=169.0  100.0 m; range=1.0−571.0 m; Figure 18), whereas 95% of cottontail radiolocations were ≤536.0 m away from a permanent watercourse (mean=289.0  142.0 m; range=1.7−670.0 m; Figure 18). Swamp rabbits also were significantly closer to MBLH patches (F1, 79=9.05, p=0.003) and farther from agriculture (F1, 79=12.36, p=0.001) than cottontails. My study represents the most complete record to date on survival and habitat use by swamp rabbits. Rabbit survival was positively associated with basal area so management actions that provide woody cover for concealment and thermoregulation may benefit both species. Although cottontails in my study used early-successional BLH, patterns of space and habitat use described here demonstrate that cottontails remained on the periphery of bottomlands. My study confirms the utility of early-successional BLH to both species; however, stands that are located too far from a permanent water sources are unlikely to be used by swamp rabbits, and may be less suitable for other BLH specialists as well. Allowing grasslands and crop fields to succeed into old fields containing bushes, vines, and other woody species will benefit both cottontails and swamp rabbits. Within BLH forests, canopy gaps can be created to promote tree regeneration and woody ground vegetation such as vines and shrubs. Finally, upland early-successional habitats that border bottomland forests are especially important as refugia for swamp rabbits during flooding.

The permeability of surrounding landcover types can influence the probability of animals leaving a patch and dispersing across the unsuitable matrix. The marsh rice rat (Oryzomys palustris) persists in wetlands that are often isolated by upland cover types. The goal was to quantify the permeability of three landcover types (grassland, agriculture, and forest) and calculate the landcover composition of home ranges for a population of rice rats in southern Illinois. Between March 2011 and January 2012, I trapped rice rats up to 95 m from wetlands into unsuitable cover and simultaneously followed individuals via radiotelemetry. I calculated the slope of capture rate (log-transformed) vs. distance from wetland as an inverse measure of permeability and also measured inundation, rice rat abundance, and matrix vegetation density as potential covariates explaining matrix use. I calculated mean home range size for males with the fixed kernel density method and compared landcover within home ranges to what was available in the surrounding landscape. Using generalized linear mixed models, I compared matrix capture rates and permeability levels among cover types, inundation, abundance, and vegetation density. After 13,610 trap-nights, I captured 43 rice rats in the matrix between March and September, with 24 in agriculture, 10 in grassland, and 9 in forest. I did not find permeability differed between landcover types, but did find that rice rats were captured further and more frequently in agriculture than grassland and forest cover. Both population abundance in wetlands and vegetation density < 0.5 m high had positive effects on matrix captures, while lowering water levels increased the permeability of the surrounding matrix. After radio-tracking 25 rice rats, home ranges were 3.01 ±0.57 ha and were the largest for individuals followed in early summer. Emergent vegetation was used proportionally more than would have been expected at random, indicating rice rats preferred emergent wetlands habitat at the home-range level. This study suggests that rice rats are more vagile and move through upland cover types more frequently than previously described in the literature.

Social behavior and habitat selection of river otters (Lontra canadensis) are highly variable among populations and there is limited information on how space use of this mustelid changes in human-modified environments. Understanding the spatial ecology of river otters is important for efforts focused on habitat management and preventing human-wildlife conflicts. My objectives were to quantify: (1) home ranges and core areas, (2) second- and third-order habitat selection, and (3) relationships between home-range size and intensity of human development for river otters in southern Illinois. VHF transmitters were used to track river otters during 2014-2016. Home-range and core-area sizes then were compared between males (n = 8) and females (n = 10), as was home-range overlap. I also compared the frequency individuals were located <25 m from a conspecific between sexes. Habitat selection at the second and third orders was analyzed with an eigen-analysis of selection ratios. Male river otters had larger home ranges and core areas than females. Home ranges of males overlapped frequently; lack of core-area overlap among females suggested they may be territorial. Males also were located <25 m from a conspecific more frequently than females (P = 0.023), and male-male dyads shared space more than male-female and female-female dyads (P = 0.002). Herbaceous and wooded wetlands were most strongly selected for at both second- and third-order scales, but streams and ponds also were selected. Regarding terrestrial cover types, river otters selected land with vegetative cover over areas with impervious surface (e.g., parking lots and shopping centers). Forests were selected over crop fields at the third-order, but not second-order, scale. Use of urbanized land was uncommon for river otters, and there was a positive relationship (P = 0.004) between home-range size and the percentage of home range within developed open space (e.g., roads and residential lawns). The habitat selection and sociality of river otters in southern Illinois varied among individuals, as it does among river otter populations throughout North America. By recording sex differences in social behavior and selection of aquatic and upland habitat, my study provides wildlife biologists with a better understanding of river otter space use throughout a rural-urban gradient.

Aspectos da ecologia populacional do tuco-tuco-das-dunas (Ctenomys flamarioni) foram estudados na região costeira da Estação Ecológica do Taim, com o objetivo de determinar características ecológicas, como a estrutura populacional e o tamanho e a forma da área de vida (home-range), utilizando a radiotelemetria numa população de Ctenomys flamarioni. O estudo foi desenvolvido entre dezembro de 2011 a março de 2013, foram realizadas 06 campanhas a cada trimestre de acordo com as estações sazonais com duração de quatro dias consecutivos. A extensão da área de estudo definida abrangeu uma área de 6 ha. O tamanho da área de vida foi calculado pelo software Biotas 2.0, utilizando o estimador de Kernel (95%) e o estimador MCP (100%). Foram capturados 56 indivíduos de Ctenomys flamarioni, 18 machos e 38 fêmeas. Foram realizadas 59 recapturas. A estimativa do tamanho populacional indicou uma pequena oscilação na taxa populacional entre as campanhas de amostragens sazonais. O valor da densidade demográfica média encontrada foi de 3,92 ± 0,5 indivíduos por hectare. No estudo de rádio-telemetria obteve-se 169 localizações dos indivíduos monitorados. Os resultados obtidos demonstraram uma nítida diferença entre estes dois métodos. O tamanho médio de área da vida obtido em Kernel (95%) foi de 1.860,3 m2 ± 832,0 para as fêmeas e 2.168,3 m2 ± 2.597,5 para os machos. Já os resultados obtidos pelo método MCP foram de 707,1 m2 ± 230,1 nos para as fêmeas e 3.334,5 m2 ± 2.632,1 para os indivíduos machos. A utilização da ferramenta de rádio-telemetria se mostrou uma grande aliada para responder algumas questões encontradas no programa de marcação e recaptura, como a taxa de deslocamento, aspectos comportamentais e mortalidade. / I studied aspects of population ecology of the Tuco-tuco of the dunes (Ctenomys flamarioni), such as population structure and home-range size and shape, in the coastal region of the Taim Ecological Station. The study was conducted from December 2011 to March 2013, in six campaigns of four consecutive days. Sampling was stratified along the annual seasons. My study site comprised a strip of sand dunes of 500 X 120 meters, totaling an area of 6 ha. I captured 56 individuals of Ctenomys flamarioni, 18 males and 38 females, and registered 59 recapture events. Population size estimates indicated short term population oscillations between seasons, but a long term equilibrium, with population sizes similar at the beginning and at the end of my study. The average population density was 3.92 ± 0.5 individuals per hectare. Using radio-telemetry, I obtained 169 locations. The results showed a clear difference between the two methods used to estimate home-range. The average home-range obtained with Kernel (95%) was 1860.3 ± 832.0 m2 for females and 2168.3 ± 2597.5 m2 for males. Home-ranges estimated by the MCP were 707.1 ± 230.1 m2 for females and 3334.5 ± 2632.1 m2 for males. The use of radio telemetry proved to be a great ally to answer some questions raised with mark-recapture analyses, such as, the rate of displacement, mortality and behavioral aspects.

This study provides an insight into carnivores´ responses to urban conditions. The main goal of this study is to examine changes of population densities and home range sizes of eight mesocarnivore species along the gradient from natural to urbanized habitats by gathering and assessing available data.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The blue manakin Chiroxiphia caudata is a bird of the Pipridae family with distribution in the Atlantic Forests of Brazil, Argentina and Paraguay. Males have a lekking polygynous system, aggregating in certain places that females visit to copulate. As soon as the female is at the lek, the courtship displays begin. There is a linear dominance hierarchy between adult males, in which only the dominant, or alpha, copulates with the female. The objective of this study was to examine the development of social interactions of the blue manakin.The study was conducted in two deciduous forest areas in Santa Maria, RS. Leks were observed from October 2009 to February 2010. Results are presented in two chapters. The first one reports the hierarchy ascension of adult males in the absence of the dominant male. In one lek there was a subordinated male (gamma), which participated in another lek as an alpha male. When the dominant male (alpha) left the main lek, the beta was expected to take its place. Nevertheless, it was the gamma that actually did. Thus, I propose a system of main and secondary leks to explain the structural differences of the observed leks. The second chapter reports the use of space by different adult males according to their hierarchies as well as by young males. Adult males presented home ranges of similar size and that overlap according to the hierarchical level of individuals. However, it was found a preference for certain perches according to the status of the male. Yet the distances traveled were similar. / O tangará Chiroxiphia caudata é um pássaro da família Pipridae, cuja distribuição ocorre nas florestas Atlânticas do Brasil, da Argentina e do Paraguai. Os machos possuem sistema de leques poligínicos, no qual os machos se agregam em determinados locais e as fêmeas visitam para acasalar. Assim que a fêmea está presente no leque, iniciam-se as exibições de corte. Existe, entre os machos adultos, uma hierarquia de dominância linear, no qual somente o dominante, ou alfa, copula com a fêmea. O objetivo deste estudo foi analisar o desenvolvimento das interações sociais do tangará. O estudo foi realizado em duas áreas de floresta estacional decidual em Santa Maria, RS. O período de observação dos leques foi de outubro de 2009 a fevereiro de 2010. Os resultados foram divididos em dois capítulos. O primeiro trata da ascensão hierárquica dos machos adultos na ausência do macho dominante. Em um leque, havia um macho subordinado (gama) que participava de outro leque como alfa. Quando o macho dominante (alfa) deixou o leque principal, o beta deveria ocupar seu lugar, no entanto foi o gama quem o fez. Assim, propõem-se um sistema de leques principais e secundários para explicar as diferenças estruturais dos leques observados. O segundo capítulo trata do uso do espaço por diferentes machos adultos, conforme suas hierarquias, e jovens. Os machos adultos possuem áreas de vida de tamanho semelhante e a sobreposição espacial é maior quanto maior for o nível hierárquico dos indivíduos. No entanto, foi encontrada preferência por determinados poleiros, conforme o status do macho. Já as distâncias percorridas foram semelhantes.

Elucidating the factors that drive variation in the abundance and distribution of organisms is central to ecology. Variables that explain the spatial variation in the abundance of organisms primarily include environmental (e.g., temperature and precipitation) and biotic factors (e.g., competition, predation, and parasitism). An important mechanism influencing the spatial distribution of organisms, at least at small spatial scales, is habitat selection. Traditionally, habitat selection theory has assumed that animals select habitat based on their ability to acquire depletable resources within that habitat, especially food. Ectotherms, however, may instead select habitat based on their ability to process food within the habitat, given the strong dependence of body temperature (and performance) on environmental temperature in this group. The major objective of my thesis was to determine whether energy gain, habitat selection, and population density were driven primarily by food availability or by temperature in ectotherms. I used Sceloporus jarrovii lizards as a study species because these lizards occur at high densities and in similar habitat across a broad altitudinal range. In Chapter 1, I tested the prediction, central to the thermal coadaptation hypothesis, that juvenile lizards prefer body temperatures that maximize their net energy gain. I also tested whether lizards shifted their preferred body temperatures to correspond to the optimal temperature for different energetic states, as per Huey’s (1982) energetics model. In Chapter 2, I determined whether the home range size and density of lizards shifted in response to manipulations of food availability and/or thermal quality within a site. In Chapters 3 and 4, I determined whether mean body condition, individual growth rate, and population density were driven by food availability or thermal quality. In Chapter 3, I visited 32 study sites over a 1,550 m altitudinal range within a year; whereas in Chapter 4, I food-supplemented five out of 10 study sites where I performed mark-recapture over a period of three years. Overall, my thesis demonstrates that both food availability and thermal quality of the habitat drive energy gain, habitat selection, and population density. Juvenile S. jarrovii preferred body temperatures that maximized net energy gain, regardless of energetic state. Although they did not shift their preferred body temperature range depending on energetic state, the difference in the optimal temperature for net energy gain between states (0.4°C), may have been too small to warrant a change in behaviour. Within a site, S. jarrovii increased their home range size and occurred at higher densities as natural food availability increased, and decreased their home range size and occurred at lower densities as the thermal quality under the rocks increased. This suggests that S. jarrovii respond to food availability and thermal quality at different scales, selecting territories based on thermal quality and home ranges based on food availability. Over 32 sites, the abundance of S. jarrovii increased with food availability, whereas the mean body condition increased and the rate at which lizards attained their maximum body size decreased with elevation (at lower thermal quality). In the three-year study, mean body condition and individual growth rate decreased and population density increased with thermal quality, but the strength of the relationship depended on natural food availability. Overall, both food availability and thermal quality of the habitat drive energy gain, habitat selection, and population density; however, thermal quality is often the stronger driver. Thus, improvements to habitat selection models should incorporate habitat thermal quality to improve predictions on how ectotherms distribute themselves on a landscape.

O jacaré-de-papo-amarelo (Caiman latirostris) é um crocodiliano de médio porte que apresenta ampla distribuição na América do Sul. O avanço das atividades antrópicas pode afetar negativamente suas populações. No entanto, a espécie aparentemente apresenta capacidade de colonizar habitats alterados em resposta à destruição dos seus habitats naturais, por isso, estudos nestes ambientes são importantes a fim de orientar futuros programas de conservação da espécie. Este estudo apresentou como objetivos verificar a estrutura populacional, uso do espaço e variação de nicho no jacaré-de-papo-amarelo em paisagem silvicultural, além de determinar fatores de discriminação isotópicos. O presente estudo foi realizado em duas fazendas de silvicultura na bacia hidrográfica do Alto Paranapanema, estado de São Paulo. Os jacarés foram capturados por meio de armadilhas e com auxílio de laço de cabo de aço. No primeiro capítulo desta tese foram investigados aspectos da estrutura populacional da espécie. No total foram capturados 16 filhotes, 28 juvenis (?: 7; ?: 21) e 8 adultos (?: 4; ?: 4). A estimativa da abundância populacional foi de 51 indivíduos (I.C. 95%: 36 - 70 indivíduos), desconsiderando os filhotes nas análises. A densidade estimada foi 2,6 indivíduos/ha (I.C. 95%: 1,8 - 3,5 indivíduos/ha) e a biomassa estimada foi de 13,3 kg/ha (I.C. 95%: 9,2 - 17,9 kg/ha). A densidade linear 11,3 indivíduos/km (I.C. 95%: 7,9 - 15,5 indivíduos/km). No segundo capítulo foram abordados aspectos ligados à área de vida e movimentação da espécie. Oito animais adultos (4 ? e 4 ?) foram monitorados por meio de radiotelemetria. A média da área de vida da espécie foi estimada segundo o mínimo polígono convexo e kernel 95% em 96,6 ± 183,9 ha e 43,2 ± 78,6 ha, respectivamente. Não houve diferença entre os sexos. O deslocamento diário médio foi 37,6 ± 18,6 m/dia. Os animais apresentaram deslocamento diário marginalmente maior durante o período reprodutivo. A matriz da paisagem mostrou permeabilidade ao deslocamento dos animais. No terceiro capítulo foram descritos os fatores de discriminação entre a dieta e tecidos do jacaré-de-papo-amarelo e possíveis diferenças entre classes etárias. As razões isotópicas de carbono e nitrogênio foram determinadas em amostras de unha e pele coletadas de 18 animais de cativeiro e em 15 amostras de sua dieta. O ?13C foi 1,2 ± 0,1? para a unha e 0,9 ± 0,2? para a pele; o ?15N foi 1,1 ± 0,1? para a unha e 0,8 ± 0,2? para a pele. Estes valores são menores que os comumente assumidos em estudos ecológicos (3-5 ?). Os resultados deste estudo enfatizam a necessidade da determinação de fatores de discriminação específicos para cada táxon, ao contrário de assumir valores médios a partir da literatura. No quarto capítulo foram abordadas possíveis variações ontogenéticas e sexuais de nicho na espécie utilizando análises isotópicas das unhas dos animais capturados. Foi identificada variação ontogenética discreta de nicho isotópico e diferença sexual somente para os juvenis. Estes resultados podem indicar uma possível exploração distinta dos recursos, com consequente redução na competição intraespecífica. / The Broad-snouted caiman (Caiman latirostris) is a medium size crocodilian widely distributed in South America. The advancement of human activities can negatively affect their populations. However, the species apparently has ability to colonize anthropic environments in response to the destruction of their natural habitat, so study these environments are important in order to guide future conservation programs for specie. This study presented as objectives verify the population structure, space use and niche variation in Broad-snouted caiman in landscape silvicultural, besides determining discrimination isotopic factors. This study was conducted in two silvicultural farms in the Alto Paranapanema watershed, São Paulo state. The caimans were captured at night with baited traps and with the aid of steel cable. In the first chapter of this thesis we investigated aspects of the population structure. In total, were captured 16 hatchlings, 28 juveniles (?: 7; ?: 21) and 8 adults (?: 4; ?: 4). The estimation of population abundance for the study area was 51 individuals (C.I. 95%: 36 - 70 individuals), excluding the hatchlings in the analyzes. The estimated density was 2.6 individuals/ha (C.I. 95%: 1.8 - 3.5 individuals/ha) and biomass was 13.3 kg/ha (C.I. 95%: 9.2 - 17.9 kg/ha). The linear density was 11.3 individuals/km (C.I. 95%: 7.9 - 15.5 individuals/km). In the second chapter, we have discussed aspects related to the home range and movement. Eight adults animals (4 ?: 4 ?) were monitored by radio telemetry. The average home range was estimated according to the minimum convex polygon and kernel 95% in 96.6 ± 183.9 ha and 43.2 ± 78.6 ha, respectively. There was no difference between the sexes. The average daily movement was 37.6 ± 18.6 m/day. The animals daily movement marginally higher during the reproductive period. The matrix showed some landscape permeability displacement of animals. In the third chapter we have described the discrimination factors between diet and tissues of Broad-snouted caiman and possible differences between age groups. The isotopic ratios of carbon and nitrogen were determined in claw and scute samples collected from 18 captive animals and in 15 samples of their diet. The ?13C was 1.2 ± 0.1 ? for claw and 0.9 ± 0.2 ? for scutes; the ?15N was 1.1 ± 0.1 ? for claw and 0.8 ± 0.2 ? for scutes. These values were much lower than the values commonly assumed in ecological studies (3-5 ?) and similar to a previous study with crocodilians. The results of this study emphasize the need to determine discrimination factors specific to taxa instead of assuming average values derived from the literature. In the fourth chapter, were addressed possible ontogenetic and sexual niche differences in species using isotope analysis of animals claws. We identified a discrete ontogenetic variation in the isotopic niche and sexual difference only for juveniles. These results may indicate differences in the exploitation of food resources and a consequent reduction in intraspecific competition.