Nesting Ecology and Habitat Selection of Western Burrowing Owls (Athene Cunicularia Hypugaea) in the Thunder Basin National Grassland, Northeast Wyoming PDF Download
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Author: Sarah J. Lantz
Publisher:
ISBN:
Category : Burrowing owl
Languages : en
Pages : 81
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Author: Sarah J. Lantz
Publisher:
ISBN:
Category : Burrowing owl
Languages : en
Pages : 81
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Category :
Languages : en
Pages : 498
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Author: Kyle Blake Larson
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ISBN:
Category : Burrowing owl
Languages : en
Pages : 0
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The availability of mammal burrows is often considered the most important habitat requirement for burrowing owls (Athene cunicularia), but little is known regarding factors that affect the density and distribution of fossorial mammals and their burrows, and how they ultimately influence habitat selection of burrowing owls. Soils are believed to play an important role in this relationship, particularly with respect to habitat selection at a landscape scale. In this study, I assessed whether burrowing owls in southcentral Washington prefer to nest in certain soils, and whether selection corresponds to increased burrow availability in those soils. I also evaluated whether the association between burrow temperature and soil texture may be one factor influencing nest habitat selection of burrowing owls. Roadside surveys conducted in 2007 and 2008 indicated that the density of burrowing owl nests in the study area was quite low (0.14 nests km-2). Comparisons between use and predicted burrowing owl habitat did not show an association between habitat selection and soils, although burrowing owls did nest more frequently in loamy sand and sandy loam soils. Soils influenced the distribution and abundance of badger (Taxidae taxus) burrows, which are the primary type of burrow used by burrowing owls in eastern Washington. However, habitat use by nesting burrowing owls was not correlated with the availability of badger burrows in the primary soils. Owls nested in soils where burrows were both abundant and rare. Field tests comparing temperature inside simulated nest burrows indicated that burrow temperature was significantly different among soil textures, and that burrow temperature was inversely related to the amount of coarse material (sand) in the soil. However, I failed to detect a relationship between soil texture and temperature inside burrows that had been previously occupied by burrowing owls, although sample sizes were low for this comparison. Hence, differences in burrow temperature related to soil texture alone are not likely to explain why burrowing owls may associate with certain soils. Temperature differences among previously occupied burrows may have been related to burrow characteristics that influenced convective heat exchange (e.g., entrance orientation, tunnel length, convolution), although further research is needed to test this hypothesis.
Author: Noelle A. Ronan
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ISBN:
Category : Burrowing owl
Languages : en
Pages : 136
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I used a comparative and experimental approach to examine nest habitat selection, reproductive success, and nest site fidelity of burrowing owls (Athene cunicularia) in a large, non-fragmented grassland in southwest California. In 1999, I compared habitat characteristics between nest sites (n = 31) and randomly selected, unoccupied burrows (n = 31) in the local vicinity of the nest (paired burrows). In 2000, I compared habitat characteristics between nest sites (n = 33) and randomly selected, unoccupied burrows (n 32) within the study area (unpaired burrows). I examined reproductive success and variation in nest habitat characteristics, diet quality, and intraspecific competition using data from 1998, 1999, and 2000. I experimentally (n = 11 control and 11 treatment nests) assessed the effect of satellite burrow (multiple auxiliary burrows near the nest) use on productivity and behavior. I found little variation in habitat between nest sites and unoccupied burrows. Habitat selection was not strong when nests and unoccupied burrows were spatially correlated (paired burrows). However, nest sites had a larger number of large diameter burrows, satellite burrows, and perches than the unpaired burrows. Nest success (I young fledged) and productivity (the number of young alive at 14 -21 days) varied substantially among some years, though the habitat variables I tested did not explain reproductive success when both failed and successful nests were evaluated. When nests were successful, productivity was influenced by rodent consumption. Nest fidelity within the breeding season was highly correlated with nest success. Nest abandonment occurred at 83% (n = 15 of 18), 92% (n = 12 of 13), and 83% (n = 20 of 24) of the failed nests in 1998, 1999, and 2000, respectively. Results of the experimental manipulation of satellite burrow access showed that productivity did not differ between groups but demonstrated that burrowing owls will adjust their behavior to use satellites. Owls in the treatment group (71%; n = 5 of 7) responded by moving their families to areas with access to satellite burrows but none of the control group owl families moved. This study illustrates the importance of identifying critical factors affecting reproductive success of burrowing owls in large grasslands. Maintenance of burrowing mammal populations to provide nest and satellite burrows will be important for protecting burrowing owls. Also, temporal dynamics influenced reproductive success. Habitat characteristics that enhance foraging ability may benefit productivity, especially in years of low rodent numbers. Furthermore, temporal variation in nest success may lead to low nest site fidelity.
Author: Carol Grover-Mariner
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ISBN:
Category : Electronic dissertations
Languages : en
Pages : 110
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Category : Nature
Languages : en
Pages : 222
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Author: April F Joy Manalo Stevens
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ISBN:
Category : Burrowing owl
Languages : en
Pages : 228
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ISBN: 9781339259864
Category :
Languages : en
Pages : 94
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Ecological studies are defined by three primary categories of activity: the collection of field data, statistical analysis, and modeling. Of the several meanings of the term "model," it is used here in the sense of simulation modeling, when the purpose is to extend the existing state of knowledge to potential scenarios not yet encountered or impossible to evaluate with field methods. This dissertation encompasses all three types of studies. In Chapter 1, we manipulated vegetation and squirrels in a replicated, large-scale field experiment. The intended objectives of the field experiment had a strong applied purpose, to provide managers with a cost-effective tool for restoring hybrid ecosystems with improved suitability for the recovery of Western Burrowing Owl (Athene cunicularia hypugaea) on protected reserve lands. We implemented short-term restoration treatments to re-establish key ecological processes provided by an ecosystem engineer, the California Ground Squirrel. The experiment produced new information about burrow availability for owls, squirrel habitat selection, and the positive feedback of squirrel activity on vegetation structure in grasslands. This chapter represents the type of focused field experiments needed to reduce uncertainty around parameters in the study system. The results can be used to inform management directly or to parameterize simulation models. Chapter 2 presents a statistical analysis that characterizes the variability in available field data sources in order to produce precise and robust estimates of the mean and variance of demographic parameters. We employed Bayesian Markov Chain Monte Carlo estimation to estimate four key life history parameters of Western Burrowing Owl: adult and juvenile ixmortality, nest success, and nest productivity. In this suite of vital rates the estimate of juvenile mortality of Burrowing Owls was least well-resolved. While our specific goal was to provide improved estimates of burrowing owl vital rates, this approach is broadly applicable to synthesizing the findings of multiple field studies, linking demographic estimates to simulation models, and informing management decisions. In Chapter 3 we developed, parameterized, and evaluated the stability of an agent based model of burrowing owls that uses explicitly defined individual behavior to examine the relationship between owl settlement decisions and the habitat quality consequences for reproduction and population growth. In an analysis of model sensitivity, juvenile mortality consistently was the most influential input parameter, followed by adult owl mortality and squirrel mortality. We conducted an uncertainty analysis to verify the reliability of the model. Observations of densitydependent owl population growth provided evidence that the model produces biologically realistic population-level emergent behavior. We utilized the model to conduct a factorial experiment comparing the relative influences of owl density and a gradient of landscape proportions of low vs. high habitat qualities, which showed that initial owl density is also an influential driver of population persistence. The model currently enables qualitative consideration of the proximate mechanisms behind population decline, including the factors that attract owls to disturbed edge habitats. The progression of the three types of studies is generally expected to begin with data collection in the field. The data is then evaluated with statistical analyses, which indicates whether the amount and quality of data is sufficient for inference. Simulation modeling is conducted as the xfinal step. Frequently, simulations are delayed until researchers believe they have a thorough understanding of the system. However, this dissertation compressed all three steps into a relatively short period of time. Proceeding directly to simulation created a feedback of valuable information to both our field efforts and statistical analyses, both by identifying the most influential parameters in the system, and by showing the potential range of model outcomes from current levels of parameter uncertainty. This identified needs for additional field data and updated analyses. This dissertation illustrates the value of planning for all three steps at the outset of research projects, to enable iterative improvement in data collection and parameter estimates, in order to provide managers with the best possible set of predictions and recommendations from modeling.
Author: Eboni Shamere Duke
Publisher:
ISBN:
Category : Burrowing owl
Languages : en
Pages : 106
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Burrowing owl (Athene cunicularia) populations are declining across much of their native range and populations are increasingly moving into human disturbed landscapes. Most research has focused on native habitats and it is not well understood how owls use these anthropogenic habitats and influences on foraging, dispersal, and survival. I studied the foraging behavior, dispersal and survival of juvenile burrowing owls in urban, greenspace and agricultural dominated habitats in Doña Ana County, New Mexico. Juvenile burrowing owls exhibited a preference to forage in agricultural habitats and selected greenspace over urban habitats. Foraging preference did vary across individuals; however, agriculture and greenspace were consistently selected over urban sites. Owls foraging in agricultural areas were observed hunting along canals, in weedy ditches, and along associated farm roads, whereas owls in greenspace foraged in city parks, golf courses, and patches of native habitat. Dispersal from the natal area varied by dominant habitat type with owls in greenspace dispersing farther than owls in agricultural and urban habitats. When agricultural habitats were divided into continuous and fragmented patches, juveniles from nests in continuous agricultural areas dispersed similar distances to those in greenspace and farther than those in fragmented agricultural habitats. Dispersal distance was modeled in relation to year, sex, and landscape variables around the nest, but was not strongly influenced by variables measured. Juvenile burrowing owl survival was also modeled in relation to these variables and positively influenced by the percentage of agriculture surrounding the nest; however, after model averaging agriculture the confidence intervals bound zero indicating uncertainty with this variable. In this study 26% of juveniles died before dispersal from the study area and survival was highest in agriculture (83%) compared to urban (55%) and greenspace (54%) habitats. Patches of greenspace within urban areas did not appear to protect owls from mortality risk and owls nesting in areas surrounded by predominantly urban habitats also had low survival. The irrigation canal system associated with agriculture fields in the southwest acts as a corridor for owl dispersal and provides nesting habitat that promotes higher survival, possibly by lower levels of disturbance and better foraging habitats.
Author: Michelle A. Ocken
Publisher:
ISBN:
Category : Burrowing owl
Languages : en
Pages :
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