Habitat loss is the greatest contributor to the decline of species globally and thus understanding habitat use and the consequences fragmentation has on biodiversity is a fundamental step towards management and recovery. I conducted a radio-telemetry study to examine the spatial ecology and the effects of roads on Eastern Hognose Snakes (Heterodon platirhinos), a species at risk, in the Long Point Region of Ontario, Canada. I tested habitat selection at multiple spatial scales and I found that within the home range, snakes avoided agricultural land and selected open sand barrens, particularly for nesting. At the local scale, snakes avoided mature overstory trees and used younger patches of forest. Used locations had more woody debris, logs and low-vegetative coverage than locations selected at random. Eastern Hognose Snakes also showed avoidance of paved road crossings in their seasonal movements, but readily crossed unpaved roads. Management efforts for this species at risk should be placed on the conservation of sand barrens and on the construction of road underpasses to prevent genetic isolation of populations.

Conservation programs for breeding ducks in North America are typically designed to enhance nest success by establishing or restoring attractive perennial nesting cover or promoting favourable agricultural practices. Thus, a central objective is to attract ducks to habitats where females have higher survival and reproductive rates, primarily greater nest success. Using data collected from 1993 – 2000, I investigated hypotheses proposed to explain inconsistent patterns of habitat selection detected during nesting and brood–rearing stages in free-ranging mallards (Anas platyrhynchos) throughout the Canadian Prairie Parklands. By simultaneously considering indices of body condition and size of male and female mallards and plumage score of males, I also evaluated the role of male quality in reproductive investment and patterns of breeding success of females. In general, wild mallards mated assortatively by body condition but not body size. Yearling females nested earlier and had higher nest survival when mated to males with better plumage quality. When paired with larger-bodied males, yearling females renested more often, whereas nest and brood survival increased among older females. I characterized the habitat composition of 100 and 500 m radius buffers surrounding nest sites and related habitat features to survival of nests, broods and females. Habitat selection trade-offs were detected among perennial habitats and planted cover, such that nest survival increased in these habitats whereas duckling survival decreased. Furthermore, at large spatial scales, nest survival decreased in areas with greater amounts of cropland whereas duckling survival increased. Survival rates of females increased with greater amounts of seasonal wetlands, but nest survival decreased in such areas. Semi-permanent wetlands were associated with decreased nest survival at larger spatial scales, but associated with higher nest success at finer scales. Benefits of increasing perennial and planted cover habitats to increase nest survival could be partly offset by costs in terms of lower duckling survival, whereas opposite patterns existed in areas of abundant seasonal. The restoration of seasonal wetlands in perennial habitats could offset these trade-offs but net impacts of habitat selection and survival trade-offs on annual reproductive success must first be evaluated.

Climate change can affect habitat availability and species interactions at several spatial and temporal scales. I explored niche partitioning and spatial variation of Rock (Lagopus muta) and White-tailed Ptarmigan (L. leucura) in southwest Yukon. I examined habitat selection of foraging areas within a population and patches within foraging areas in a sympatric population of Rock and White-tailed Ptarmigan. At the larger foraging area scale, Rock Ptarmigan used areas with greater shrub cover compared to White-tailed Ptarmigan. At the smaller patch scale, both species selected patches with greater rock cover, but differed in other patch features. Second, I examined spatial variation in abundance of both ptarmigan species between the Ruby and Kluane Ranges using pellet count and transect surveys. Relative abundance was lower in the Kluane Range based on pellet counts, but transect surveys proved inadequate as a measure of population density. The Kluane Range also had fewer positive degree days above 0 C and a greater mean standard deviation of NDVI, and was composed of finer textured colluvium compared to the Ruby Range, which could influence relative abundance of ptarmigan. / Ecology

Thesis (Ph. D.)--University of Washington, 1995. / Vita. Includes bibliographical references (leaves [74]-80).

Master of Science / Department of Biology / David A. Haukos / In the southern Great Plains, the lesser prairie-chicken (Tympanuchus pallidicinctus; hereafter LEPC), an obligate grassland species, has experienced significant population declines and range contractions with subsequent conservation concern. Management actions often use land cover types to make inference about habitat quality. Relatively little information is available related to grazed rangelands to guide conservation. The influences of land cover types and livestock grazing on LEPC habitat selection have not been researched extensively in western Kansas. I evaluated the influence of land cover types and grazing management on vegetation characteristics, habitat selection, and nest/adult survival of LEPC in western Kansas. Females were captured and radio-marked to monitor habitat use, nest success, and adult survival. Grazing and vegetation data were collected via producer correspondence and vegetation surveys, respectively. Vegetation composition and structure differed across land cover types, which can be used to make inferences about LEPC habitat quality. Habitat selection analyses corroborated the importance of breeding habitat in close proximity to leks (<3 km) and identified land cover types selected for nesting (Conservation Reserve Program, Limy Upland, Saline Subirrigated) and brooding (Conservation Reserve Program, Red Clay Prairie, Sands, Sandy Lowland). Conservation Reserve Program patches positioned near rangelands contributed to LEPC reproductive success in northwest Kansas. In grazed lands, LEPC selected habitat close to leks (<3 km) and large pastures (>400 ha), exhibiting low-moderate stocking densities (<0.4 AU/ha), and low-moderate levels of deferment during the grazing season (60-100 days). Nest site selection was negatively influenced by increasing distance from a lek and grazing pressure. Daily nest survival rates were negatively influenced by increasing grazing pressure and high levels of stocking density. Annual adult female survival was negatively influenced as forage utilization (% forage removed) increased. Heterogeneity (coefficient of variation and standard deviation) of visual obstruction was decreased at stocking densities > 0.26 AU/ha. Future conservation actions should consider the potential of land cover types to create adequate vegetation structure, and manage rangelands with low-moderate stocking densities and deferment and greater pasture areas. The relationship between habitat selection and proximity of lek sites (< 5 km) should be used to identify quality LEPC habitat.

A fragmentação e a redução do habitat são as principais causas do declínio populacional e de biodiversidade no mundo, seguidas pela sobrecaça. Essas perturbações levaram a família Cracidae ao posto de família de aves mais ameaçada das Américas. Diversos programas de reintrodução já foram conduzidos com cracídeos no Brasil, a começar pela reintrodução do mutum-do-sudeste (Crax blumenbachii Spix, 1825) na Fazenda Macedônia (FM) em Ipaba, MG. O objetivo deste trabalho foi estimar o tamanho e a densidade populacional e a razão sexual dos mutuns existentes na FM e analisar o uso da paisagem pela espécie. Os dados foram coletados ao longo de 6 meses por transecção linear (esforço amostral: 280 km) e analisados segundo protocolos de amostragem por distância linear e ocupação. O tamanho populacional foi estimado em 34 (10 111) indivíduos e a densidade em 2,36 (1,58 7,79) indivíduos/km². Entretanto, a proporção de área utilizada foi estimada em 21%, indicando que a densidade para as áreas realmente ocupadas pode ser mais alta. A intensidade de uso da área parece estar correlacionada principalmente à densidade do sub-bosque e à oferta de suplementação alimentar. A taxa de crescimento populacional foi estimada em -0,047 (-0,137 0,018), o que indica um declínio. É possível que este declínio esteja ligado ao tamanho reduzido da população, que a torna mais susceptível à estocasticidade demográfica, ambiental e genética e ao efeito Allee. Os mesmos fatores também podem estar provocando um desvio na razão sexual, estimada em 0,35 (0,20 0,47). / Fragmentation and habitat loss are the two main causes of population and biodiversity decline, followed by overhunting. Such impacts made the Cracidae family the most endangered bird family in American continents. In Brazil, many reintroduction programs focused on cracids. The first one reintroduced the Red-billed Curassow (Crax blumenbachii Spix, 1825) in Ipaba, MG, Brazil. This work aimed to estimate the population size and density, the sex ratio and the landscape use of the Red-billed Curassow population reintroduced in Ipaba. We collected the data along 6 months through line-transects, totalizing 280 km of effort. The analysis followed distance sampling and occupancy protocols. We estimated the population size in 34 (10 111) birds and the density was 2.36 (1.58 7.79) birds/ha. However, we estimated the proportion of area effective used in 21%, what means that the density for such area might be higher. Apparently, the intensity of habitat use is mostly correlated to the understory density and to food supplementation. We estimated the population growth rate in -0.047 (-0.137 0.018), what indicates a decrease. Its possible that the population is declining due to its size, once small populations are more likely to suffer because of demographic, environmental and genetic stochasticity and Allee effect. The same factors might explain the skewed sex ratio, estimated in 0.35 (0.20 0.47).

Habitat loss is the greatest contributor to the decline of species globally and thus understanding habitat use and the consequences fragmentation has on biodiversity is a fundamental step towards management and recovery. I conducted a radio-telemetry study to examine the spatial ecology and the effects of roads on Eastern Hognose Snakes (Heterodon platirhinos), a species at risk, in the Long Point Region of Ontario, Canada. I tested habitat selection at multiple spatial scales and I found that within the home range, snakes avoided agricultural land and selected open sand barrens, particularly for nesting. At the local scale, snakes avoided mature overstory trees and used younger patches of forest. Used locations had more woody debris, logs and low-vegetative coverage than locations selected at random. Eastern Hognose Snakes also showed avoidance of paved road crossings in their seasonal movements, but readily crossed unpaved roads. Management efforts for this species at risk should be placed on the conservation of sand barrens and on the construction of road underpasses to prevent genetic isolation of populations.

Explaining spatial and temporal variation in the abundance of species is one of the primary goals of ecology. Habitat selection, the behaviour that organisms use to choose habitat patches that maximize fitness, can explain patterns in abundance between patches at small spatial scales within the dispersal capacity of the species. However, habitat selection models assume there is a reduction in individual fitness as population density increases due to increased competition between individuals. Ectotherms, which often select habitats based on temperature, a density-independent resource, may not display density-dependent responses if temperature limits energy assimilation more than finite food resources limit energy acquisition. As predicted by their dependence on environmental temperatures, some ectotherms select habitat largely independently of population density when temperatures are far from the optimal temperature for performance. But, is density-dependence prevalent in ectotherm populations when temperatures are close to the optimal temperature for performance? Habitat selection models also assume that all individuals of a population exhibit the same strategy for maximizing fitness through habitat selection. However, differences in morphology and behaviour (e.g., reproductive strategy) can modify the optimal habitat selection strategy for different phenotypes. Finally, observed patterns in habitat selection and abundance can also be modified by competition with other species. Quantifying the relative importance of these different factors that affect habitat selection behaviour will improve our ability to predict the spatial distribution and relative abundance of organisms. The objective of my thesis was to explain spatial variation in the abundance of ectotherms, using the ornate tree lizard (Urosaurus ornatus) as a study species. In chapter one, I tested whether density-dependent habitat selection explained patterns in abundance and fitness of lizards between two habitats differing in suitability. In chapter two, I tested whether density dependent habitat selection in tree lizards was caused by intraspecific competition for food that limited body size and growth. In chapter three, I tested whether variation in reproductive strategy, as indicated by throat colour phenotype, affected space use and habitat selection in male tree lizards. Finally, in chapter four, I tested whether interspecific competition with another lizard species affected habitat selection, fitness, and abundance of tree lizards. My thesis emphasizes the importance of intraspecific competition in shaping patterns of habitat selection and abundance in terrestrial ectotherms. I show that habitat selection is strongly density-dependent despite differences in thermal quality between habitats. I show that density-dependent mortality and growth lower the fitness of individuals when populations reach high densities, and this likely caused habitat selection to be density-dependent. Despite this evidence for density-dependent habitat selection, I show considerable variation between individuals in habitat selection and space use. Males with different throat colour phenotypes select habitats differently, demonstrating that variation in morphology can influence habitat selection patterns within a population. Finally, I show that interspecific competition with another lizard affects space use and how frequently tree lizards switch habitats, but this does not lead to differences in fitness or in the relative abundance of tree lizards in habitats. Therefore, intraspecific competition for resources was the dominant force shaping the relative abundance of tree lizards in different habitats.

Host plant selection is an important process during the life cycle of lepidopterans, providing ovipositing sites for adults and food resources for the larvae. The processes behind host plant selection have been extensively studied, especially in closely related species in the context of niche separation. Empirical and theoretical studies have shown that multiple processes, such as resource competition, parasitoid avoidance and reproductive interference between interspecific individuals can affect host plant selection, often leading to niche separation. The aim of this study was to create and analyze a mathematical model using the adaptive dynamics techniques, in order to study the evolution of habitat selection. Our model incorporated three processes: Resource competition in the form of density dependent growth, parasitoid attacks and repro- ductive interference in a two species-two habitat system. It was hypothesized that the presence of parasitoids would promote co-existence through top-down control, while reproductive inter- ference would promote niche separation. The results confirmed both hypotheses. The analysis incorporating only the effect of parasitism showed the evolution of habitat separation when parasitoids attacked randomly and the evolution of co-existence in both habitats in the case of switching parasitoids. On the other hand, incorporating reproductive interference promoted the evolution of partial or complete niche separation. The extent of this process was shown to depend on the strength of reproductive interference and the initial habitat choice of the two species. Stronger reproductive interference increased the size of the set of initial conditions leading to the evolution of complete niche separation. The analysis conducted in this study demonstrated the opposing effects of parasitism and reproductive interference on the evolution of habitat selection, promoting co-existence and separation respectively.

While studies of dispersal note significant fidelity to natal site and to the site of first reproduction, few consider fidelity to other sites, and none have done so systematically. This study examined fidelity to all terrestrial sites within the study area during the course of its life, by a migratory marine predator, the southern elephant seal, Mirounga leonina. It also attempted to assess the role played by the winter haulout in terms of site fidelity. Finally it examined the influence of possible deterioration in spatial memory over time on site fidelity. The data used in this study were generated by a long-term mark-recapture programme conducted at subantarctic Marion Island. Although immature elephant seals of both sexes return to the vicinity of their natal sites, they appear to avoid popular breeding beaches, returning closest to the site previously used. At the first reproductive haulout, however, females return closer to their natal site than any other site, while males, although hauling out in the vicinity of their natal site, haul out closest to sites used in the year prior to the first breeding haulout. Subsequently, adults of both sexes breed closest to the breeding haulout of the previous year and moult closest to the moult haulout of the previous year. While males show greater site fidelity during the breeding season, there is no difference in site fidelity during the moult. Primiparous females show greater levels of site fidelity if recorded in the study site as an immature animal during either the winter or the moult haulouts. Also in female elephant seals, lower site fidelity is associated with an increase in the duration of period of absence from a site, and a lower number of visits to a site. Various factors related to site familiarity, social factors and anthropogenic disturbance may be responsible for the lack of strict site fidelity that is evident. Dispersal patterns may differ between the sexes due to differences in their life history. While purpose of the winter haulout by immature seals may be to increase familiarity with haulout sites, and thus site fidelity, the moult haulout also plays a role. / Thesis (PhD)--University of Pretoria, 2013. / Zoology and Entomology / Unrestricted