Browsing by Subject "birds"
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Item Group Based Rigging of Realistically Feathered Wings(2012-02-14) Howard, Heather VernetteDigital birds are used in computer graphics to replace live animals both for the safety of the animal and to allow for more control over performance. The current treatment of avian wings in computer graphics is often over-simplified which results in a loss realism due to the incorrect form and motion of the feathers. This research attempts to address this problem by using the structure and motion of real bird anatomy to inform the creation of biologically accurate kinematic motion for wings. The hypothesis of this thesis is that a wing rig which follows biological accuracy will appear realistic in motion and facilitate efficient animation. This thesis describes the creation of a rig generation tool, called WingCreator, usable in 3D animation software to guide the construction of biologically accurate wings while maintaining a range of artistically-driven variability in form. The control system for the kinematic motion rig is designed to provide animators with intuitive control over wing behavior intended to result in efficient re-creation of realistic wing action including flapping and folding. WingCreator was tested by two riggers and one animator to gain feedback on the tools efficacy. The user feedback indicates that the resulting rig provides a control system that facilitates efficient animation while maintaining artistic control over the wing. Users reported that realism, however, could not be judged due to the numerous contributing outside factors, such as animation, lighting and texturing, that affect the perception of realism. WingCreator and its creation methodology is intended to be placed in the public domain for use by anyone and will add to the currently slim body of knowledge for creating realistic avian wings. Once placed in the public domain it is expected that this rig will be appropriated by animators who wish to create more accurate bird wing motion and by riggers who may use the biologically-driven methodology as a model for further exploration into depictions of other animals exhibiting complex form and structural motion behaviors.Item Molecular and in vitro growth comparisons of Encephalitozoon hellem isolates from human and bird hosts(Texas A&M University, 2004-09-30) Waters, Paulette FrancescaMolecular and in vitro comparisons were performed using two isolates of Encephalitozoon hellem, one from an avian host and one from a human host, and one isolate of Encephalitozoon cuniculi from a rabbit. The molecular comparisons were performed by amplifying and sequencing the gene coding for a zinc metallo-aminopeptidase from cDNA and gDNA obtained from each of the isolates. The E. hellem sequences shared >99 % identity between each other and 70% identity with the E. cuniculi sequences. Conserved HEXXH and GXMEN motifs located within the sequences classify the protein as an aminopeptidase of the M1 family, with at least one zinc atom required for catalytic activity. In vitro growth comparisons of the isolates described above were performed under simulated "mammalian and avian conditions". The models utilized mammalian and avian cell lines and sera at incubation temperatures of 37 ?C and 40 ?C, respectively. Three separate experiments were performed. E. cuniculi grew best under the mammalian model and significantly better than both E. hellem isolates under this model. The E. hellem isolates were able to infect and replicate under both the mammalian and avian models, which reflects the zoonotic potential of these isolates.Item P450 aromatase alterations and DNA damage as avian pollution biomarkers in cliff and cave swallow breeding near the Rio Grande region, Texas(Texas A&M University, 2006-04-12) Sitzlar, Megan AnnetteThe endocrine system, specifically relating to sex hormones, and genetic material can be targets of environmental contaminants. Environmental contaminants in the Rio Grande region may originate from industrial or agricultural processes and growing populations lacking proper water and sewage infrastructure. Cliff (Petrochelidon pyrrhonota) and cave (P. fulva) swallows breeding near the Rio Grande were selected to monitor aromatase activity alterations and DNA damage. Swallows were sampled at six sites along the Rio Grande from Brownsville to Laredo, and a reference site (Somerville) 350 miles north of the Rio Grande. DNA damage, based on nuclear DNA content, was determined by flow cytometry. A significantly larger mean half peak coefficient of variation (HPCV) of DNA content in contaminated sites compared to a reference site reflects possible chromosomal damage. No detectable HPCV differences were observed in cave swallows among locations, notwithstanding the presence of mutagenic contaminants. Selenium may provide a protective role against genetic damage. However, cliff swallows from Laredo had significantly higher HPCV values than those from Somerville. DNA damage could be attributed to metals and polycyclic aromatic hydrocarbons released near Laredo. Brains and gonads, two estrogen-dependent organs, were tested for aromatase activity with a tritiated water method. Brain aromatase activity was higher, though not always statistically, for male cave and male and female cliff swallows. Dichlorodiphenyldichloroethylene (DDE) may play a role in the increased activity. Female cave swallows in Llano Grande appeared to have a greatly depressed brain aromatase activity, possibly attributed to past human use of toxaphene. Testicular and ovarian aromatase activity in cliff and cave swallows from Rio Grande was higher than in those from Somerville, though not always significantly. DDE, atrazine, sewage treatment plant contaminants (phthalates, alkylphenols, ethynylestradiol), metals, or other pollutants could play a role in the increased gonadal activity. Increased aromatase activity, in association with contaminants, may be easier to detect in testes of male birds which normally exhibit low levels of estrogen. Siterelated contaminants may be playing a role in DNA damage and aromatase alterations. This is the first known study which uses aromatase activity as an endocrine disruptor indicator in wild birds.Item Spatial and temporal winter territory use and behavioral responses of whooping cranes to human activities(2009-06-02) LaFever, Kristin E.I investigated spatial and temporal winter behavior and behavioral responses of 5 territorial whooping crane families to human activities at Aransas National Wildlife Refuge during winters 2003-2004 and 2004-2005. Adult and juvenile cranes spent the majority of the day foraging (63% and 66%, respectively). Alert behavior comprised 15% of the cranes' time-activity budgets; preening or resting, and movement each constituted approximately 7% of the time-activity budget. Adults were more alert than juveniles in Jan-Feb. The proportion of time spent in other behaviors did not differ by age. Over-winter use of territories varied spatially and temporally. Flight occurrence was highest in Nov-Dec, coinciding with establishment of territorial boundaries upon arrival at the wintering grounds. Movement velocity (meters traveled/min) also tended to be highest in Nov-Dec, which may be due to territorial defense and foraging activities. Use of land, open water, and edge habitats (land and water interface) within territories appeared to fluctuate with primary food item availability. Disproportionate use of land habitat by several crane families coincided with peak production of wolfberry (Lycium carolinianum) fruit, which occurs in Nov-Dec. Edge habitat was used disproportionately to its availability throughout the winter, most likely because this habitat type provided refuge for blue crabs (Callinectes sapidus), an important food item for whooping cranes. Several families also used open water disproportionately to its availability. Behavioral responses of whooping cranes to human activities were limited. Responses to varying frequency and intensity of human stimuli were evaluated. Most stimuli did not elicit a response. Two crane families decreased the proportion of time spent foraging during periods of high-intensity stimuli; one family increased movement during such times. Foraging behavior of one family was significantly higher when stimuli frequency was high; alert behavior significantly declined as stimuli frequency increased. The mixed responses of territorial families to varying levels of human stimuli paired with the overall high level of reproductive success of the entire population led to my conclusion that current levels of human activities are not having a detrimental impact on the Aransas-Wood Buffalo whooping crane population.Item Studies on the molecular epidemiology, pathogenesis, diagnosis and treatment of avian mycobacteriosis(2009-05-15) Saggese, Miguel DanielWe investigated the molecular epidemiology, differential susceptibility to infection and disease, pathogenesis, diagnosis and treatment of avian mycobacteriosis in captive ringneck doves (Streptopelia risoria) and in the endangered white-winged duck (Cairina scutulata), both naturally infected with Mycobacterium a. avium. Our studies in doves demonstrated lower susceptibility to infection and less severity of lesions in the white color morph compared with the non-white. Genetic mechanisms of immunity to mycobacteriosis may be contributing or determining these differences. Given that the genes that code for white coloration are sex linked in birds, it is very likely that the gene or genes modulating this different immune response to M. a. avium infection in these doves could be associated to these loci or at least located in the same sexual (Z) chromosome, as the association with white color suggest. In the same birds, spleen biopsies followed by liver biopsies had the greatest potential for the diagnosis of mycobacteriosis by the demonstration of acid-fast organisms. Additional culturing of spleen or liver biopsies significantly increased the diagnosis of mycobacteriosis. The use of polymerase chain reaction (PCR) was the less sensitive techniques. Uneven distribution and low number of organisms in the liver, spleen and bone marrow may have contributed with the low diagnostic value of PCR. In a second group of sixteen doves with mycobacteriosis from the same flock, the combination of azithromycine, ethambutol and rifampin for 180 days was well tolerated but failed to cure them. Furthermore, this study demonstrated the inefficacy of liver biopsy to evaluate treatment as well the presence of antibiotic resistance in two isolates. These results highlight that erradication of mycobacteriosis in birds is not easy to achieve. Together with the possible emergence of antibiotic resistance in potentially zoonotic mycobacteria our results suggest that the treatment of mycobacteriosis in birds should not be recommended. Finally, the last study shows that white-winged ducks are highly susceptible to at least two sequevars of M. a. avium and that mycobacteriosis is a major threat to the ex situ conservation program. The minimal heterozygosis previously shown in these ducks could be contributing to this apparently ineffective immune response.Item The effects of human disturbance on birds in Bastrop State Park(Texas A&M University, 2006-10-30) Marcum, Heidi AnnWith rapidly disappearing natural areas due to development and fragmentation, public lands provide important habitat for birds. However, the increasing use of public lands for recreation may decrease the value of these areas for bird use. Human disturbance can damage birds in many ways, including disrupting foraging or social behavior, increasing nest predation, interfering with parent-offspring and pair bonds, increasing nesting failures, and reducing the viability of fledglings. Additionally, birds may perceive humans as predators and leave an area, and the resulting decline in species abundance resembles the effects of habitat loss. Increased human outdoor activity has created the need for information regarding the effects of human disturbance on birds. I investigated the effects of human disturbance on birds in Bastrop State Park (BSP) in central Texas in 1998 and 1999. A wide variety of people use much of BSP, and many areas within the park experience significant amounts of disturbance from people and vehicles, particularly in campgrounds. I evaluated the effects of various types of human disturbance on the presence of 20 avian species, including seven neotropical migratory species. Brown-headed Cowbird (Molothrus ater), Mourning Dove (Zenaida macroura), Carolina Wren (Thryothorus ludovicianus), and Summer Tanager (Piranga rubra), were sensitive to human presence, and Blue Jays (Cyanocitta cristata), and Downy Woodpeckers (Picoides pubescens) occurred in lower abundances in sites with higher numbers of vehicles. However, other species (e.g., American Crow [Corvus brachyrhynchos], Black-and-white Warbler [Mniotilta varia], Pileated Woodpecker [Dryocopus pileatus], Red-eyed Vireo [Vireo olivaceus], Ruby-throated Hummingbird [Archilochus colubris], White-eyed Vireo [Vireo griseus], and Yellow-billed Cuckoo [Coccyzus americanus]) tolerated humans, vehicles, or both. Neotropical migratory species did not show higher sensitivity to disturbance when compared to resident species, and forest interior species were not more sensitive than edge species. My results indicate that some species, including migrants, can become habituated to human presence in protected areas with low harassment and low-intensity, predictable disturbances. Management recommendations for BSP include protecting habitat, minimizing human disturbance in some areas, providing buffer zones between humandominated zones and sites containing vulnerable species, and softening edges in campgrounds.