State highway agencies are searching for more cost-effective methods of rehabilitating roads. One sustainable solution is full-depth reclamation (FDR), a pavement rehabilitation technique that involves pulverizing and reusing materials from existing distressed pavements in place. There is, however, limited information on the long-term properties of these recycled materials. One important property, the elastic modulus, indicates the structural capacity of pavement materials and is highly recommended for design purposes by the Mechanistic Empirical Pavements Design Guide (MEPDG). The elastic modulus directly impacts selection of the overall pavement thickness, and an accurate estimation of the modulus is therefore key to a cost-effective pavement design. This thesis researched the modulus trends and functional properties of three in-service pavements rehabilitated with the FDR technique during the 2008 Virginia Department of Transportation (VDOT) construction season. Foamed asphalt (2.7% with 1% cement), asphalt emulsion (3.5%), and Portland cement (5%) were used as stabilizing agents for the FDR layers. Several deflection tests and distress surveys were conducted for the pavement sections before and after construction. An automated road analyzer (ARAN) was used to collect distress data over a period of 7 years. Deterioration models were developed to predict the durability of differently stabilized FDR pavements and compared to reference sections rehabilitated with traditional asphalt concrete (AC) overlays. The results of the moduli measured for the recycled base materials varied significantly over time. These changes were attributed to curing after construction, seasonal effects, and subgrade moisture. The structural capacity of the pavements improved irrespective of the stabilizing agent used. Rutting was higher for the foamed asphalt and emulsion sections. The International Roughness Index (IRI) was better for the cement stabilized sections compared asphalt stabilized sections. The Critical Condition Index (CCI) was similar for all treatments at the end of the evaluation period. The durability of the sections was comparable, with the cement stabilized FDR sections slightly outperforming the asphalt stabilized sections. / Master of Science / Replacing all roads in bad condition with new reconstruction or with traditional rehabilitation alternatives such as the mill and overlay will cost state highway agencies (SHAs) huge sums of funds. State departments of transportation are therefore seeking cost-effective ways to rehabilitate roads under their jurisdiction. An innovative technique being used by several SHAs today is full depth reclamation (FDR) which involves breaking down an existing roadway and immediately reusing the materials to construct a strengthened base layer for a new road. Despite the increasing use of FDR in recent years, several questions remain unanswered regarding the behavior of the strengthened base materials and their performance in the long-term under traffic loads. The elastic modulus is one material property that indicates the strength or structural capacity of pavement materials and usually impacts the selection of the overall thickness of the roadway. This thesis researched the modulus trends and functional properties of three in-service roadways rehabilitated with the FDR technique in 2008 by the Virginia Department of Transportation. Foamed asphalt (2.7% with 1% cement), asphalt emulsion (3.5%), and Portland cement (5%) were used to strengthen the FDR base layers. Several deflection tests and distress surveys were conducted for the pavement sections before and after construction. The moduli measured for the recycled base materials varied significantly over time. These changes were attributed to curing after construction, seasonal effects, and subgrade moisture. Long term performance monitoring of the projects showed that rutting was higher for the foamed asphalt and emulsion sections. The International Roughness Index (IRI), which gives an indication of the overall ride quality i.e. how smooth the pavement surface is, was better for the cement stabilized FDR sections compared to the asphalt stabilized counterparts. The structural capacity of the pavements improved irrespective of the stabilizing treatment used. The Critical Condition Index (CCI) was similar for all treatments at the end of the evaluation period. The durability of the sections was comparable, with the cement stabilized sections projected to last slightly longer than asphalt sections.

State highway agencies are searching for more cost-effective methods of rehabilitating roads. One sustainable solution is full-depth reclamation (FDR), a pavement rehabilitation technique that involves pulverizing and reusing materials from existing distressed pavements in place. There is, however, limited information on the long-term properties of these recycled materials. One important property, the elastic modulus, indicates the structural capacity of pavement materials and is highly recommended for design purposes by the Mechanistic Empirical Pavements Design Guide (MEPDG). The elastic modulus directly impacts selection of the overall pavement thickness, and an accurate estimation of the modulus is therefore key to a cost-effective pavement design. This thesis researched the modulus trends and functional properties of three in-service pavements rehabilitated with the FDR technique during the 2008 Virginia Department of Transportation (VDOT) construction season. Foamed asphalt (2.7% with 1% cement), asphalt emulsion (3.5%), and Portland cement (5%) were used as stabilizing agents for the FDR layers. Several deflection tests and distress surveys were conducted for the pavement sections before and after construction. An automated road analyzer (ARAN) was used to collect distress data over a period of 7 years. Deterioration models were developed to predict the durability of differently stabilized FDR pavements and compared to reference sections rehabilitated with traditional asphalt concrete (AC) overlays. The results of the moduli measured for the recycled base materials varied significantly over time. These changes were attributed to curing after construction, seasonal effects, and subgrade moisture. The structural capacity of the pavements improved irrespective of the stabilizing agent used. Rutting was higher for the foamed asphalt and emulsion sections. The International Roughness Index (IRI) was better for the cement stabilized sections compared asphalt stabilized sections. The Critical Condition Index (CCI) was similar for all treatments at the end of the evaluation period. The durability of the sections was comparable, with the cement stabilized FDR sections slightly outperforming the asphalt stabilized sections. / Master of Science / Replacing all roads in bad condition with new reconstruction or with traditional rehabilitation alternatives such as the mill and overlay will cost state highway agencies (SHAs) huge sums of funds. State departments of transportation are therefore seeking cost-effective ways to rehabilitate roads under their jurisdiction. An innovative technique being used by several SHAs today is full depth reclamation (FDR) which involves breaking down an existing roadway and immediately reusing the materials to construct a strengthened base layer for a new road. Despite the increasing use of FDR in recent years, several questions remain unanswered regarding the behavior of the strengthened base materials and their performance in the long-term under traffic loads. The elastic modulus is one material property that indicates the strength or structural capacity of pavement materials and usually impacts the selection of the overall thickness of the roadway. This thesis researched the modulus trends and functional properties of three in-service roadways rehabilitated with the FDR technique in 2008 by the Virginia Department of Transportation. Foamed asphalt (2.7% with 1% cement), asphalt emulsion (3.5%), and Portland cement (5%) were used to strengthen the FDR base layers. Several deflection tests and distress surveys were conducted for the pavement sections before and after construction. The moduli measured for the recycled base materials varied significantly over time. These changes were attributed to curing after construction, seasonal effects, and subgrade moisture. Long term performance monitoring of the projects showed that rutting was higher for the foamed asphalt and emulsion sections. The International Roughness Index (IRI), which gives an indication of the overall ride quality i.e. how smooth the pavement surface is, was better for the cement stabilized FDR sections compared to the asphalt stabilized counterparts. The structural capacity of the pavements improved irrespective of the stabilizing treatment used. The Critical Condition Index (CCI) was similar for all treatments at the end of the evaluation period. The durability of the sections was comparable, with the cement stabilized sections projected to last slightly longer than asphalt sections.

<p><em>Natrix tessellata </em>predstavlja vrstu neotrovne zmije koja ima &scaron;iroko rasprostranjenje.<br />Posebno interesantnu populaciju ribarica čine zmije koje naseljavaju izolovana ostrva kao &scaron;to je to slučaj na ostrvu Golem grad koje se nalazi na Prespankom jezeru u Makedoniji.</p><p>&nbsp;&nbsp;&nbsp; Imajući u&nbsp; vidu da je ova populacija na ovom lokalitetu izuzetno brojna i slabo istražena, cilj studije je bio da se ispita životna istorija date vrste zmija, njene osnovne morfolo&scaron;ke karakteristike, seksualni polimorfizam, zastupljenost različitih kolor morfi, dnevnu i sezonsku aktivnost, predaciju kao i njihove reproduktivne karakteristike.</p><p>&nbsp;&nbsp; Studija je sprovedena na ukupno 3850 jedinki ribarica na ostrvu Golem grad tokom prolećne i letnje sezone u periodu od 2008. do 2012. godine, a uključila je i određivanje kondicionog indeksa i njegovu vezu sa kolor morfama, polom i uzrasnim kategorijama.&nbsp;&nbsp;&nbsp;</p><p>&nbsp;&nbsp; Rezultati ove studije su pokazali da je populacija ribarica koja naseljava ostrvo Golem grad, specifična iz nekoliko razloga. Najpre, na relativno malom prostoru stalno je naseljen veliki broj jedinki, sa podjednakom zastupljeno&scaron;ću sve tri kolor morfe (tačkasta, siva i melanična kolor morfa) &scaron;to predstavlja specifičnost i različitost u odnosu na sve ostale lokalitete koje naseljava ova vrsta zmije. Takođe, prosečne vrednosti ispitivanih morfolo&scaron;kih karakteristika ženki su značajno veće u odnosu na mužjake u sve tri uzrasne kategorije (juvenilni, subadulti i adulti). Fertilitet i fekunditet, kao i kondicioni indeks je pokazao specifičnost u odnosu na ispitivane zone ostrva.</p><p>&nbsp;&nbsp; Sumiranjem i analizom svih iznesenih rezultata može se zaključiti da je populacija<br />ribarica <em>Natrix tessellata</em> na ostrvu Golem grad jako specifična zbog ujednačenog prisustva sve tri kolor morfe koje pokazuju svoju ekolo&scaron;ku, reproduktivnu i morfolo&scaron;ku specifičnost u odnosu na populacije ribarica koje su ispitivane na drugim lokalitetima njihovog rasprostranjenja. Kako bi se posebnost ove populacije u potpunosti&nbsp; objasnila sa različitih evolutivnih i ekolo&scaron;kih aspekata, neophodno je izvr&scaron;iti dalja ispitivanja tokom sledećih aktivnih sezona.</p> / <p><em>Natrix tessellata</em> represents one specific type of non-toxic snake that have a wide distribution. Particularly this population of dice snake is interesting because it is consists of snakes that inhabit the isolated island Golem grad in Prespa lake in FYR Macedonia.</p><p>Bearing in mind that this population at this particular site is extremely dense and poorly investigated, the goal of this study was to examine the life history of these species, its morphological characteristics, sexual polymorphism, presence of the&nbsp; different color morphs, duirnal and seasonal activity, predation and their&nbsp; reproductive &nbsp; characteristics. The study was conducted on a total of 3850 individuals of dice snake on the island Golem grad during the spring and summer season in the period from 2008. to 2012., and included the determination of the fitness index and its relationship with a color morph, sex and age categories.&nbsp;</p><p>Results of this study showed that the population of dice snakes that inhabits the island Golem grad, are specific for several reasons. First, the relatively small area has been inhabited by large number of individuals, with equal representation of all three color morphs&nbsp; (dotted, gray and melanic morph) which represents the specificity&nbsp; and diversity in relation to all other localities inhabited by this species of snake. Also, the average value of measured morphological characteristics in females&nbsp; were significantly higher than in males in all three age categories (juvenile, subadult and adult). Fertility and fecundity, and fitness index have showed the specificity acording to specific zone of the island.&nbsp;</p><p>&nbsp;&nbsp; By summarizing and analyzing of results it can be conclude that the population of <em>Natrix tessellata</em> which inhabits island Golem grad are very specific due to the uniform presence of all three color morphs that demonstrate their&nbsp; environmental, reproductive and morphological specificity in comparison of dice snakes populations that have been studied in other localities of their distribution range. In order to be fully explained unicity of this population from different&nbsp; evolutionary and ecological aspects, it is necessary to do further research during the next active seasons.</p>

Este trabalho foi realizado com o objetivo de aplicar o Modelo de Tavakoli, que é um modelo de gerência de pavimentos para vias urbanas, para análise de priorização de vias urbanas em cidade de médio porte. Para isso se utilizou um estudo de campo previamente realizado pela Prefeitura Municipal de Suzano e pelo Laboratório de Mecânica de Pavimentos da Universidade de São Paulo no município de Suzano, no ano de 2007, com o qual foi criado um banco de dados das vias do município. Naquele estudo foi empregado o modelo HDM-4 do Banco Mundial para a priorização de intervenções de manutenção nas vias públicas. No presente trabalho buscou-se elaborar um estudo comparativo entre aquela solução e a solução atingida pelo modelo de Tavakoli para um mesmo conjunto de vias. Para este trabalho o Modelo de Tavakoli foi adaptado para planilhas eletrônicas e aplicado em um conjunto de seções de pavimentos, permitindo a determinação de uma lista de prioridades de intervenções. Posteriormente, essas intervenções foram simuladas para o mesmo conjunto de vias, buscando a priorização dos serviços, com o modelo HDM-4 versão 1.0. Através deste trabalho foi possível concluir que os dois critérios estudados podem ser úteis para gerenciar vias urbanas, pois priorizaram as intervenções necessárias nas vias urbanas analisadas. Foi possível verificar que o Modelo de Tavakoli se revelou mais conservador, por ser um critério fechado, com um índice de prioridades dependendo diretamente do índice da condição do pavimento e do volume diário médio de tráfego, afetando diretamente a classificação das seções. No Modelo HDM-4 a classificação das seções e os valores de irregularidade não tiveram uma sincronia, pois o HDM-4 é um modelo de critérios abertos, que permite ao usuário acrescentar vários parâmetros, e com estes foi possível reproduzir uma situação um pouco mais próxima da realidade. / This study was conceived in order to apply the Tavakoli Model, which is a pavement management system for urban roads, aiming the analysis of prioritization of urban streets in a mid-sized city. A field study previously conducted by Suzano City and the Pavements Mechanics Laboratory of the University of São Paulo in Suzano City in 2007 was used, from which was created a database of the towns streets. In that study, the Highway Design and Management (HDM-4) Model of the World Bank was employed for prioritizing maintenance work on public roads. In this study it was sought to develop a comparative study between the mentioned solution and the one reached by Tavakolis Model in the same set of roads. In this research the Tavakoli Model was adapted for the spreadsheets and applied to a set of pavement sections, allowing the determination of a priority list of interventions including the specific type of intervention for each segment. Subsequently, these same types of strategies or interventions were simulated for the same set of paths, seeking the prioritization, with HDM-4 Model version 1.0. Through this research it was possible to conclude that both criteria studied can be useful for managing urban roads, because they prioritized the necessary interventions in the urban roads analyzed. The Tavakoli Model proved to be more conservative, on account of being a closed criterion, with a priority index depending directly on the pavement condition index and average daily volume of traffic, affecting the classification of the sections directly as well. In the HDM-4 Model, the classification of the sections and values of the International Roughness Index did not match, due to HDM-4 being an open criteria model, which allows the user to add several parameters, and they can lead to more realistic report.

<p>The condition of the herring (<em>Clupea harengus</em>) in the Baltic Sea has decreased during the past 30-40 years. This decrease could be explained by different factors; (1) change in diet due to changes in zooplankton community, (2) changes in water temperature and salinity, (3) increasing nutrient inputs and (4) competition for food with other species such as sprat (<em>Sprattus sprattus</em>). In this study the change in condition was analysed using the Fulton’s condition index, and by looking at age and sex of the fish as well as the season and locationthe fish was caught, the differences between these factors were presented. Data from the national Swedish contaminant monitoring programme where used from four locations in the Baltic Sea and two locations at the Swedish West coast. The data was analysed using multiple regressions in R Commander. The result show that the condition, and the temporal trends in condition value, varies at different locations, with higher condition values and increasing temporal trends at the Swedish West coast, compared to the Baltic Sea with lower condition values and where three of four locations show decreasing temporal trends. The condition varied between spring and autumn caught herring as well, while age and sex showed less significant differences.</p>

The condition of the herring (Clupea harengus) in the Baltic Sea has decreased during the past 30-40 years. This decrease could be explained by different factors; (1) change in diet due to changes in zooplankton community, (2) changes in water temperature and salinity, (3) increasing nutrient inputs and (4) competition for food with other species such as sprat (Sprattus sprattus). In this study the change in condition was analysed using the Fulton’s condition index, and by looking at age and sex of the fish as well as the season and locationthe fish was caught, the differences between these factors were presented. Data from the national Swedish contaminant monitoring programme where used from four locations in the Baltic Sea and two locations at the Swedish West coast. The data was analysed using multiple regressions in R Commander. The result show that the condition, and the temporal trends in condition value, varies at different locations, with higher condition values and increasing temporal trends at the Swedish West coast, compared to the Baltic Sea with lower condition values and where three of four locations show decreasing temporal trends. The condition varied between spring and autumn caught herring as well, while age and sex showed less significant differences.

abstract: The accurate prediction of pavement network condition and performance is important for efficient management of the transportation infrastructure system. By reducing the error of the pavement deterioration prediction, agencies can save budgets significantly through timely intervention and accurate planning. The objective of this research study was to develop a methodology for calculating a pavement condition index (PCI) based on historical distress data collected in the databases from Long-Term Pavement Performance (LTPP) program and Minnesota Road Research (Mn/ROAD) project. Excel™ templates were developed and successfully used to import distress data from both databases and directly calculate PCIs for test sections. Pavement performance master curve construction and verification based on the PCIs were also developed as part of this research effort. The analysis and results of LTPP data for several case studies indicated that the study approach is rational and yielded good to excellent statistical measures of accuracy. It is believed that the InfoPaveTM LTPP and Mn/ROAD database can benefit from the PCI templates developed in this study, by making them available for users to compute PCIs for specific road sections of interest. In addition, the PCI-based performance model development can be also incorporated in future versions of InfoPaveTM. This study explored and analyzed asphalt pavement sections. However, the process can be also extended to Portland cement concrete test sections. State agencies are encouraged to implement similar analysis and modeling approach for their specific road distress data to validate the findings. / Dissertation/Thesis / Masters Thesis Civil Engineering 2015

Este trabalho foi realizado com o objetivo de aplicar o Modelo de Tavakoli, que é um modelo de gerência de pavimentos para vias urbanas, para análise de priorização de vias urbanas em cidade de médio porte. Para isso se utilizou um estudo de campo previamente realizado pela Prefeitura Municipal de Suzano e pelo Laboratório de Mecânica de Pavimentos da Universidade de São Paulo no município de Suzano, no ano de 2007, com o qual foi criado um banco de dados das vias do município. Naquele estudo foi empregado o modelo HDM-4 do Banco Mundial para a priorização de intervenções de manutenção nas vias públicas. No presente trabalho buscou-se elaborar um estudo comparativo entre aquela solução e a solução atingida pelo modelo de Tavakoli para um mesmo conjunto de vias. Para este trabalho o Modelo de Tavakoli foi adaptado para planilhas eletrônicas e aplicado em um conjunto de seções de pavimentos, permitindo a determinação de uma lista de prioridades de intervenções. Posteriormente, essas intervenções foram simuladas para o mesmo conjunto de vias, buscando a priorização dos serviços, com o modelo HDM-4 versão 1.0. Através deste trabalho foi possível concluir que os dois critérios estudados podem ser úteis para gerenciar vias urbanas, pois priorizaram as intervenções necessárias nas vias urbanas analisadas. Foi possível verificar que o Modelo de Tavakoli se revelou mais conservador, por ser um critério fechado, com um índice de prioridades dependendo diretamente do índice da condição do pavimento e do volume diário médio de tráfego, afetando diretamente a classificação das seções. No Modelo HDM-4 a classificação das seções e os valores de irregularidade não tiveram uma sincronia, pois o HDM-4 é um modelo de critérios abertos, que permite ao usuário acrescentar vários parâmetros, e com estes foi possível reproduzir uma situação um pouco mais próxima da realidade. / This study was conceived in order to apply the Tavakoli Model, which is a pavement management system for urban roads, aiming the analysis of prioritization of urban streets in a mid-sized city. A field study previously conducted by Suzano City and the Pavements Mechanics Laboratory of the University of São Paulo in Suzano City in 2007 was used, from which was created a database of the towns streets. In that study, the Highway Design and Management (HDM-4) Model of the World Bank was employed for prioritizing maintenance work on public roads. In this study it was sought to develop a comparative study between the mentioned solution and the one reached by Tavakolis Model in the same set of roads. In this research the Tavakoli Model was adapted for the spreadsheets and applied to a set of pavement sections, allowing the determination of a priority list of interventions including the specific type of intervention for each segment. Subsequently, these same types of strategies or interventions were simulated for the same set of paths, seeking the prioritization, with HDM-4 Model version 1.0. Through this research it was possible to conclude that both criteria studied can be useful for managing urban roads, because they prioritized the necessary interventions in the urban roads analyzed. The Tavakoli Model proved to be more conservative, on account of being a closed criterion, with a priority index depending directly on the pavement condition index and average daily volume of traffic, affecting the classification of the sections directly as well. In the HDM-4 Model, the classification of the sections and values of the International Roughness Index did not match, due to HDM-4 being an open criteria model, which allows the user to add several parameters, and they can lead to more realistic report.

Submitted by Carlos Augusto Rolim da Silva Junior (carlos_jrolim@hotmail.com) on 2015-11-19T15:51:43Z No. of bitstreams: 1 arquivototal.pdf: 2129832 bytes, checksum: 3b684f127d50c659a84b4938455dd401 (MD5) / Made available in DSpace on 2015-11-19T15:51:43Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2129832 bytes, checksum: 3b684f127d50c659a84b4938455dd401 (MD5) Previous issue date: 2013-08-14 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Variations in the Body Condition Index (BCI), glycemia and ketonemia of Artibeus planirostris (Chiroptera: Phyllostomidae) were analyzed in Tabuleiro and Atlantic Forest areas of Paraíba State, at field and captivity conditions. BCI was chosen based on the minimum influence of forearm length on body mass and evaluated according to sex, reproductive status, location and time of capture. Glycemia and ketonemia were also correlated with BCI and other variables. Variations in the BCI and glycemia were recorded after capture, fasting and feeding bats in captivity. The results showed that Le Cren’s Relative Condition Factor (Kn) and Simple Ratio with Curve Fitting (CFt) indices were the most suitable for A. planirostris. Blood glucose was correlated with Kn and proved to be a good method to validate the BCI. In Guaribas Biological Reserve, females had higher Kn, probably related to biases in the methodology or energy reserves during reproductive status. Tabuleiro’s bats had higher Kn and glucose levels than those in Atlantic Forest, which may indicate sub-sampling by the exclusion of bats in the canopy of the latter area. The twelve hours of collection indicated that A. planirostris forages throughout the night and presents a variation of Kn and glucose, especially during early morning, when it reaches the maximum levels before it returns to the shelter. In captivity, bats showed a great variation of Kn and glucose levels after fasting and feeding, recording Kn measures for these states that can be used as a parameter for field studies in the region. Blood glucose remained at normal values for mammals, but about 30% of the bats had levels higher than normal during capture in all areas, probably due to stress. Ketone bodies have been correlated only to glucose, and thus were not considered a good method to validate Kn in these animals. / As variações no Índice de Condição Corporal (ICC), glicemia e cetonemia de Artibeus planirostris (Chiroptera: Phyllostomidae) foram analisadas em áreas de Tabuleiro e Mata Atlântica da Paraíba em campo e cativeiro. O ICC escolhido foi baseado na menor influência do comprimento do antebraço na massa corporal e avaliado de acordo com o sexo, estado reprodutivo, local e horário de coleta. A glicemia e cetonemia também foram correlacionadas entre si, com o ICC e as demais variáveis, e variações no ICC e glicemia foram registradas após captura, jejum e alimentação de morcegos em cativeiro. Os resultados mostraram que o Fator de Condição Relativa de Le Cren (Kn) e a Razão Simples com Ajuste de Curva (AjC) foram os índices mais indicados para A. planirostris. A glicemia esteve correlacionada com o Kn e se mostrou um bom método para validar o ICC utilizado. Na REBIO Guaribas, as fêmeas tiveram maior Kn, provavelmente relacionado a vieses na metodologia ou a reservas energéticas durante o estado reprodutivo. Os morcegos do Tabuleiro obtiveram maior Kn e glicemia que os da Mata Atlântica, o que pode indicar subamostragem pela exclusão de morcegos que forrageavam no dossel da última área. As doze horas de coleta indicaram que A. planirostris forrageia durante toda a noite com variação de Kn e glicemia, sobretudo durante a madrugada, quando atinge o valor máximo antes de retornar para o abrigo. Em cativeiro, os morcegos apresentaram grande variação de Kn e glicemia em jejum e após a alimentação, registrando medidas de Kn para estes estados que podem ser utilizadas como parâmetro para estudos em campo na região. A glicemia manteve valores considerados normais para mamíferos, mas cerca de 30% dos morcegos apresentaram níveis acima do normal após a captura em todas as áreas, provavelmente devido ao estresse. Os corpos de cetona estiveram correlacionados apenas aos níveis de glicose e, portanto, não foi considerado um bom método para validar o Kn nestes animais.

abstract: Niche variation among sexes and life stages within a population has been documented in many species, yet few studies have investigated niche variation within demographic groups or across ecological contexts. We examined the extent to which pregnant California sea lions (Zalophus californianus) at each of three breeding colonies target alternative prey resources and habitats. The three colonies are distributed across distinct regions of the Gulf of California, Mexico and have divergent population dynamics. We compared the nature of niche variation among colonies and investigated the fitness consequences of different foraging strategies within each colony. We analyzed the &delta;13C and &delta;15N values from fur collected from 206 suckling pups to characterize relative maternal foraging locations (&delta;13C) and trophic levels (&delta;15N) during the metabolically demanding late stages of gestation and lactation that occur simultaneously in California sea lions. The &delta;13C and &delta;15N values were regressed against pup body condition index values to compare the relative individual-level fitness benefits of different maternal foraging strategies. We found that the nature and extent of niche variation differed among colonies. Niche variation was most pronounced at the two largest colonies that appear to experience the highest levels of intraspecific competition and the variation was consistent with habitat features. One colony (Granito) displayed two distinct foraging groups with indistinguishable median pup body condition values, whereas the second (San Jorge) exhibited continuous niche variation and pup body condition varied in relation to maternal foraging location and trophic level, suggesting disparities among alternative foraging strategies. For the smallest colony (Los Islotes), females occupy similar niches with a few outliers. Body condition values of pups at this colony were most variable, but did not vary with maternal foraging strategy. Our results provide evidence for intrapopulation niche variation among demographically similar individuals during a period of high metabolic stress and reproductive importance. This work suggests possible fitness benefits conferred by alternative foraging strategies, and calls into question the common assumption that members of a population are ecologically equivalent. Future research aimed at understanding animal foraging strategies should consider the nature and extent of niche variation in the context of local ecological conditions. / Dissertation/Thesis / M.S. Biology 2013