In the southwestern United States there is a delicate balance between the existing grasslands and the rodent fauna. The purpose of this investigation was to determine the influence of secondary succession of native grasslands upon the ecology and distribution of small rodents. Two methods of determining the rodent species were plot quadrates and trap lines using Sherman live traps.

Desert mule deer (Odocoileus hemionus crooki) abundance and distribution, deer activity and diet, fawn survival, and predation were studied in Big Bend National Park, Texas from 15 January 1980 to 9 December 1981. Deer abundance was correlated with total plant, forage, and succulent densities but was also related to perennial water abundance and bed site availability. Fawn production and survival were related to spring rainfall. Diurnal and annual deer activity were influenced by temperature where spring and winter had longer daily activity compared to summer. Daily activity by deer was highest during the morning and evening. Forage use varied seasonally with browse use decreasing from spring to winter with a corresponding increase in use of forbs. Diets of two deer herds were compared and during drought periods forb use decreased until summer rains occurred. Prior to the rains, deer relied on evergreen browse species. Additionally, deer within mesic areas had a higher use of forb species contrasted with deer within xeric areas. Predator diet significantly changed with a decline in the deer population determined from pellet-group transects. Mountain lions (Felis concolor) used smaller prey including javelina and lagomorphs. Coyotes (Canis latrans) fed opportunistically by increasing use of insects, birds, reptiles, and lagomorphs. Bobcats (Lynx rufus) increased use of lagomorphs with little change in other prey species. Given alternate prey species, predator populations remained relatively constant given the deer decline.

Within Big Bend National Park, the unconformable contact between the Buda Limestone and the overlying Boquillas Formation represents the Commanchean-Gulfian boundary. Previous studies of the geochronology of this interval have relied primarily on provincial ammonite faunas rather than foraminifera, and place the Buda and basal Boquillas in the Lower Cenomanian. Because of its indurated nature, a comprehensive foraminiferal biozonation has not been acquired for the Buda Limestone. Recent revisions to Cretaceous foraminiferal biozonations and taxonomies necessitates a new biostratigraphic study of the Buda - Boquillas interval. The overlapping ranges of F. washitensis, G. bentonensis, G. caseyi, P. appenninica, P. delrioensis, P. stephani, and R. montsalvensis place the Buda within the upper portion of the Early to Middle Cenomanian Th. globotruncanoides Zone. Microkarst found on the surface of the Buda Limestone has been interpreted as representing a subaerial exposure and sequence boundary. However, microkarst-like features can result from subaqueous or intrastratal processes. Carbon and oxygen stable isotope analysis of the lower and middle Buda has indicated a mean δ13C value of 1.73‰ VPDB, which is in line with other values reported from the Lower Cenomanian. The top 2.6m of Buda contains a 0.62‰ negative δ13C shift from 1.88‰ VPDB to 1.26‰ VDPB in a 40 cm interval, expected if subaerial exposure occurred. Higher variation in measured carbon isotope values beneath the contact also lend evidence for meteoric alteration. The standard deviation in δ13C values from the top 2.8 m of the Buda is 0.207, which is 2.16 times larger than the rest of the studied section at 0.096. The Buda contains a shallow pelagic-dominated fauna of heterohelicids (45-90%), globigerinellids (3-37%), and hedbergellids (4-22%). Intermediate-depth globigerinellids display an initial increase followed by a marked decrease in abundance upsection, interpreted as sea level transgression and regression, respectively. The lower contact of the Buda with the Del Rio Clay has been previously interpreted as a subaerial exposure, and a P:B break from ~0% planktonics in the upper Del Rio to ~80% in the Buda supports this claim. This study therefore interprets both the upper and lower contacts of the Buda as sequence boundaries. The overlying 1.2 m Boquillas is nearly devoid of benthics and represents a deeper assemblage including the double-keeled Dicarinella sp., as well as several Upper Cenomanian (D. algeriana Subzone) species. Based on foraminiferal data, the duration of the Buda - Boquillas unconformity is roughly equivalent to the missing Th. reicheli and Th. greenhornensis Biozones, or a sizable portion of the Middle Cenomanian. / Systematic paleontology -- Biostratigraphy of the Buda Limestone -- Biostratigraphy of the lowermost Boquillas Formation -- Stable isotope geochemistry. / Department of Geological Sciences

During the New Deal, the Civilian Conservation Corps (CCC) put young men to work in state and national parks across the United States. One of such parks, Big Bend National Park, is the focus of this study. The CCC had two camps within the park, one from 1934 to 1937 and another from 1940 to 1942. During their time in Big Bend, the CCC constructed many projects including a road, trails, cabins, and other various structures. The purpose of this study is to delineate the role of the CCC in creating Big Bend National Park and the experience of the CCC during their time in the Big Bend camp. This study determines the role of the CCC through a discussion of the planning done by the CCC for Big Bend National Park and the work completed by the CCC in the park. In doing so, it argues that the CCC played a substantial and significant role in the development and character of the park. This study works to understand the experience of the CCC in Big Bend through a discussion of education, safety, and an investigation of a commanding officer. Through this discussion, the role of the federal government and national organization in the local camps can be seen, as can the value they placed in the enrollees.

The histories of acoustic ecology, field recording, and soundscape composition are intertwined. This combination of disciplines has lead to the potential for powerful insights, but an over-emphasis on music composition using recorded sound has to led to some problematic tendencies in the study of soundscapes. I begin by tracing the development of acoustic ecology and related disciplines, leading to a proposal for a practice of acoustic ecology that centers the study of all sounds from an ecological perspective and incorporates the insights of creative practices. I include the results and data from my acoustic surveys in Patagonia, Iceland, and Texas. These three locations are varied in their climate, and they are all threatened by noise pollution or human interference from one source or another. Each survey plots out the daily sound activity in a given location and then includes information such as decibel level and the amount of anthropogenic noise. Using the field recordings from my acoustic surveys, I composed a non-linear piece, Resonance Ecology, that generates soundscapes by combining sounds from different locations based on connections such as geography or weather patterns. There is also the option for acoustic performers to perform alongside the electronics, creating an unpredictably evolving soundscape. The structure of the piece mirrors the ecosystems that serve as the foundation and inspiration of the piece. Importantly, the composition is not meant to represent the real ecosystems, but rather serves as an surreal ecosystem portraying my experience in these locations.