Humans are modifying the global landscape at an unprecedented scale and pace. As a result, species are declining and going extinct at an alarming rate. Here, I investigate two main aspects of species’ declines: what factors are contributing to their declines and how effective our conservation efforts have been. I assessed one of the main mechanisms for protecting species by looking at the Endangered Species Act (ESA) in the United States. I examined three separate indicators of species declines for different groups of species: range contractions in Canadian imperilled species, declines in abundance in global amphibian populations and increases in temporal variability in abundance in North American breeding birds. I found that change in recovery status of ESA listed species was only very weakly related to the number of years listed, number of years with a recovery plan, and funding. These tools combined explained very little of the variation in recovery status among species. Either these tools are not very effective in promoting species’ recovery, or species recovery data are so poor that it is impossible to tell whether the tools are effective or not. I examined patterns of species’ declines in three different groups in relation to a number of anthropogenic variables. I found high losses of Canadian imperiled bird, mammal, amphibian and reptile species in regions with high proportions of agricultural land cover. However, losses of imperiled species are significantly more strongly related to the proportion of the region treated with agricultural pesticides. This is consistent with the hypothesis that agricultural pesticide use, or something strongly collinear with it (perhaps intensive agriculture more generally), has contributed significantly to the decline of imperiled species in Canada. Global increases in UV radiation do not appear to be a major cause of amphibian population declines. At individual sites, temporal changes in amphibian abundance are not predictably related to changes in UV intensity. Variability in species’ abundance of North American breeding birds, after accounting for mean abundance, is not systematically higher in areas of high human-dominated land cover or climate change. Rather, it appears that areas with a high proportion of human-dominated cover come to have a higher proportion of highly abundant, and thus more variable, species.

Once abundant in the Texas and Louisiana coastal prairie, currently the Attwater’s Prairie Chicken (Tympanuchus cupido attwateri, APC) is close to extinction. Efforts to increase the size of the remaining populations at the Attwater Prairie Chicken National Wildlife Refuge (APCNWR) and the Galveston Bay Prairie Preserve (GBPP) with releases of captive-reared individuals are part of the APC captive- breeding initiative. However, after a decade of yearly releases, the populations are not reaching viable sizes. I analyzed post-release survival data of individuals released at the APCNWR from 1996 to 2005. Results suggest that age at release or date of release had little influence on survival of captive-breed APC. At two weeks post-release, survival estimates (SE) were 0.76 (0.03) for females and 0.82 (0.04) for males. Approximately 50% of the females and 33% of the males died within the first 60 days post-release. Survivorship during the breeding season showed that male survival (0.36) was higher than female survival (0.23). Survivorship from the median release date to beginning of the breeding season was 52% for males and 39% for females. Mean female survival was 155 days, while median survival was 94 days. For males, mean survival was 135 days and the median was 81 days. Results from a stochastic simulation model, which was developed based on the survival analysis of APC on the APCNWR, confirmed that releasing individuals closer to the beginning of the breeding season and sex ratio at release had little effect on population growth. Regardless of the number of individuals released annually, population sizes immediately prior to the release dates were only 11–12% of the population sizes immediately after the release dates. At current mortality rates, simulated APC populations could not sustain themselves even if reproductive parameters were increased to the maximum rates reported for APC, or to the maximum rates reported for the closely related Greater prairie chicken. Based on these results, the APC may face extinction within the next decade unless conservation efforts succeed on increasing reproductive success and greatly reducing mortality rates.

To accommodate for human population growth along the Texas I-35 corridor, land is becoming increasingly urban and decreasingly pervious, modifying the infiltration and runoff rates in the Edwards Aquifer, especially to its spring fed Upper San Marcos River (USMR). Contaminants like heavy metals and organic chemicals can accumulate on impervious surfaces and with runoff, enter into the USMR at potentially harmful levels. The objective of this study was to determine how the population of an endangered Edwards Aquifer species, the fountain darter (Etheostoma fonticola), might respond to potential water quality changes associated with urbanization. I developed a stochastic, sex and stage-structured population dynamics simulation model that represents the relationships between urbanization, springflow variations, contamination levels, and natural history of the fountain darter. Future fountain darter population trends (2008-2040) were simulated under 10 treatments of nine scenarios. A simulation scenario (n=50) corresponded to one of three variations of springflow (random, high and low flow) and one of three variations in percentage of runoff entering the river (100, 50 or 30). The 10 treatments were variations on water quality: uncontaminated (1), contaminated by Cu (2), Zn (3), Cd (4), Cr (5), polycyclic aromatic hydrocarbons (PAH) (7), bifenthrin (8), carbaryl (9) and dicamba (10) and an additive affect of Cu, Cr, Cd, and Zn (6). Simulating ideal conditions, the average darter population from 2008-2040 was 54155+2969 (mean+SE) individuals. Contaminant treatments that caused a significant (p<0.001) decline in the population by 2040 under 100% runoff conditions were the all metal (650 plus/minus 640), Cu (3141 plus/minus 265), PAH (4621 plus/minus 475), Zn (6169 plus/minus 5406), and Cd (27987 plus/minus 6751) scenarios. With 50% runoff, the all metals (15740 plus/minus 5455), Cu (16815 plus/minus 6263), PAH (19675 plus/minus 995), and Zn (15585 plus/minus 3097) treatments simulated significantly lower populations (p less than 0.001). At 30% runoff, Cu (23976 plus/minus 6787), the all metal (25853 plus/minus 7404) and PAH (28167 plus/minus 1194) treatments decreased the population significantly (p less than 0.001). Over all scenarios, copper, zinc and PAHs caused >50% decline in the population. Assuming 100% or 50% of all San Marcos sub-basin runoff is directly entering USMR, there could currently be levels of Cu, Zn, and PAHs higher than what darters can withstand.

Habitat selection research has focused on the role of vegetative and geologic habitat characteristics or antagonistic behavioral interactions. Conspecifics can confer information about habitat quality and provide positive density-dependent effects that may result in improved fitness, resulting in positive behavioral responses to conspecifics as a habitat selection strategy. I conducted 3 replicated, manipulative experiments to investigate use of conspecific cues in habitat selection for the golden-cheeked warbler (Dendroica chrysoparia) using simulated conspecific vocalizations during pre-settlement and post-breeding periods, across a range of woodland canopy cover. I measured territory density, pairing, and fledging success in paired treatment and control units. Territory density was >2 times higher in treatment units across the range of canopy (P = 0.02). Pairing success was positively correlated with territory density (P = 0.008). Territory density response was higher for pre-settlement than post-breeding treatment (P = 0.004). I found pre-settlement and post-breeding conspecific cues influence golden-cheeked warbler habitat selection, inducing settlement in previously unoccupied areas, and producing aggregations within areas of similar vegetative characteristics. Better understanding of social information use in habitat selection can improve our understanding of species distributions, yielding more accurate predictive distribution models; improve our ability to predict impacts of habitat changes on habitat use, survival, reproduction, and ultimately fitness; and provide a potential tool for attracting individuals to restored or managed sites.

Centaurea tchihatcheffii Fisch. &amp / Mey. is a critically endangered annual endemic plant found only in Ankara. This study aimed to determine its distributional range, metapopulation status, the effects of agricultural activities, and assess conservation options. Occurrences and population size estimates were carried out by ground surveys. Two adjacent subpopulations were intensively studied during 2004-2008. Plant and seed demographic data were collected in the field and by laboratory tests. Field experiments simulated the effects of agricultural practices. Risks of extinction and possible impacts of different management actions were investigated through a population viability analysis (PVA) by constructing a two-stage stochastic model. Six scenarios involving different management actions were run with 10,000 replications each using RAMAS Metapop. A total of 14 patchily distributed subpopulations were found to have an extent of occurrence of &gt / 700 km2. Herbicide applications caused extreme mortality and reduced germination success, and were shown to be the major anthropogenic threat against long-term survival of C. tchihatcheffii. Tillage led to an increase in density and reproductive success in the following year. PVA simulations for most scenarios predicted extinction of both subpopulations within 4 to 95 years, but a conservation management scenario involving delayed tillage ensured viable populations with a combined size of 21 million individuals. PVA results demonstrated that timing and frequency of tillage is crucial. Therefore, we propose tillage to be carried out after seed set every other year for protected subpopulations to ensure their long term persistence. Alternatively, unprotected subpopulations elsewhere can benefit from organic or nature-friendly farming.

The coastal zone of Belize is home to the largest recorded number of the threatened Antillean manatee (Trichechus manatus manatus) within the species' Caribbean range. The objectives of my study were: (1) to determine long-term trends in aerial survey counts and indices of the manatee population in the coastal zone of Belize; and (2) to examine the seasonal change in manatee distribution among habitats in the coastal zone. Standardized extended-area aerial surveys were conducted along the entire coastline of Belize in the dry and wet seasons of 1997, and 1999 - 2002. Manatees were counted in five habitat categories: cay, coast, estuary, lagoon, and river. Total sightings per survey ranged from 90 to 338; the greatest number was counted in the 2002 wet season. Calf percentage ranged from 5 to 13. A slight negative trend in total counts was significant for dry-season, not wet-season surveys, indicating an interactive effect of season and year. Based on analysis of variance, the Abundance Index (transformed manatee sightings per hour) did not differ significantly among years, although it varied significantly within year by season and habitat by season. In applying a spatial approach, the general survey route was buffered 1 km on both sides, and 1 km grids were overlaid and classified by habitat type. The presence or absence of each cell for each survey was used in likelihood ratio tests of the single and interactive effect of season and habitat. The Index for river habitat was higher in the dry season, while cay habitat was higher in the wet season. Overall, near-shore habitat (estuary, lagoon, and river) showed a higher Index than did the offshore habitat (cay and coast) although the total number of sightings was higher offshore. Considering the interactive effect of year, season, and habitat, long-term studies are needed, in both seasons, and among all habitats to account for variation. Continued broad-scale surveys, along with metapopulation analysis would fine-tune the understanding of specific sites, enhancing integrated coastal zone management for protected species and their habitat systems.

Ashe Juniper encroachment onto privately owned rangelands in Central Texas has resulted in significant degradation of the ecological condition of these lands, and a subsequent public concern for the hydrologic function, wildlife habitat, and livestock production these historically predominant grasslands provide. The result has been an interest and public investment in land restoration programs such as the removal and management of brush via landowner cost-share. Implementation of a publicly funded land restoration program requires the allocation of millions of dollars of public funds on private lands over large geographic areas that represent hundreds of landowners with varying property management objectives, tract sizes, ecological conditions, and geologic characteristics. This study describes the development, accuracy, and application of a decision support geographic information system (DSGIS) for land restoration programs in the Leon, Lampasas, and Bosque River watersheds in the Brazos River basin of Central Texas. The spatially referenced data layers and associated database within the DSGIS provide the capability to assemble site specific information including vegetation cover, endangered species habitat, landowners, ecological sites, elevation and slope, hydrologic characteristics, and political boundaries to support policy and implementation decisions for Ashe Juniper (Juniperus ashei) brush control and management and goldencheeked warbler (Dendroica chrysoparia) habitat restoration programs. The goldencheeked warbler is a federally listed endangered species with a breeding range limited to the oak-juniper woodlands of Central Texas. The data layers were developed with the support of ongoing research from the Leon River Restoration Project (LRRP) in Coryell and Hamilton counties. One hundred and eighty-eight (188) sub-watersheds were delineated within the project area and prioritized for implementation of an Ashe Juniper brush control program and a golden-cheeked warbler habitat restoration program. Costs associated with the clearing and stacking of Ashe Juniper were estimated for selected subwatersheds based on projected landowner participation and an analysis of actual costs from the LRRP. Sub-watersheds were targeted for the implementation of an Ashe Juniper brush control and golden-cheeked warbler habitat management program in Bosque, Coryell, Lampasas, Bell, and Burnet counties. Detailed tables were also developed to document the density and quantity of pertinent layer attributes within each of the 188 sub-watersheds.

Loggerhead sea turtles in coastal waters often sustain injuries from vessel impacts. The influences of vessel hull configuration and propulsion system type on the incidence and severity of wounds in turtle/vessel interaction were investigated. Full-scale field tests using two vessels with deep-vee hulls were performed. An artificial carapace with a sandwich composite design of a closed-cell polyurethane foam core with faces constructed of polyester resin infused with glass microspheres was developed. As a basis for comparison, a number of cold-stunned green turtle carcasses were also used in the field experiments. Two vessels, a 5.4 m boat with an inboard jet-drive engine and a 7.3 m boat with an outboard 4-bladed propeller, were operated at planing speed, 40 km/h. The field test results revealed similar patterns and severity of injuries between the synthetic turtles and the green turtle carcasses. Statistical analysis of the field test results indicated the influence of hull type alone on the severity of turtle damage was minimal, and none of the tests conducted using a jet drive engine resulted in injuries to the shell that would be considered lethal, regardless of the vessel hull type, speed, or the animal's depth in the water at impact. Conversely, injuries occurring as a result of propeller and/or skeg impact at planing speed were always classified as fatal. A finite element analysis of the artificial turtle was performed to determine the force at which a carapace fractures from hull impact alone. The results of the finite element analysis suggest that hull impacts of common recreational jet-propulsion vessels are unlikely to cause lethal carapace fractures in loggerhead sea turtles.

Diss. (sammanfattning) Umeå : Sveriges lantbruksuniv., 2009. / Härtill 4 uppsatser.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management