21 |
A TECHNIQUE TO IDENTIFY POTENTIAL ELK HABITAT IN THE WHITE MOUNTAINS OF ARIZONA.Kramer, Susan Spear. January 1983 (has links)
No description available.
|
22 |
Disturbance and habitat factors in a small reserve : home range establishment by black rhinocerous (diceros bicornis minor)Odendaal, Karen 18 January 2012 (has links)
MSc., Faculty of Science, University of the Witwatersrand, 2011 / Black rhinos are being moved to small protected areas in an attempt to expand their range;
and factors commonly found within these small protected areas could influence black rhino
ecology. From the literature we understand how biological factors affect rhino resource
selection but not in the context of small reserves. This study investigates the home range
establishment of black rhinos and those factors commonly associated with small reserves
that affect rhino habitat-use as well as weigh the relative importance of each of them. The
factors considered were human disturbances such as residences, lodges, roads and fences,
slope, elevation, perennial water, burnt areas and vegetation type. Minimum convex
polygon, 50% core and 95% local convex hull (LoCoH) was used to generate home ranges
from sightings data collected for 17 individuals. The mean 95% LoCoH home range was 3.77
km² (95% CI: 2.92- 4.63, n=17), and is comparatively small in relation to the adaptive kernel
home ranges of previous studies. A use-availability resource selection function showed that
black rhinos avoided areas close to residences, lodges, camps, and perennial water, and
these variables played a bigger role than their selection for thicket vegetation. These factors
have a highly significant effect on rhino resource selection, and this effect is magnified due
to the density of human disturbances and water points commonly found in small reserves.
It is essential that this knowledge be applied in the management of reserves protecting
black rhinos.
|
23 |
The use of logistic regression for developing habitat association modelsSjamsoe'oed, Roza 13 May 1994 (has links)
Quantitative habitat models of wildlife-habitat relationships are developed to
formalize our current understanding about an ecological system. A habitat
association model is one of these models that is useful for answering questions
about how the habitat is occupied, how much growth habitat is required by the
animal, or how the animal selects its food and habitat.
Radio telemetry is adopted as a technique for studying home range and habitat
use. The major objective of a radio telemetry study is to collect behavioral or
demographic data in order to be able to estimate population parameters for home
range and habitat selection.
A radio telemetry study is a kind of multinomial experiment. The Logistic
Regression Model is often used for estimating the relationship between animal
activities and the habitat characteristics of the location used (animal preference).
However, this model is not a good model for the telemetry data. Under this model,
the slope parameter estimate becomes lower and farther from the true value as the
Average Habitat Quality (AHQ) increases, with Diversity fixed. The Multinomial
Model is better suited to telemetry data.
Using the Logistic Regression Model, a habitat association study can be
conducted in conjunction with adaptive cluster sampling. In terms of the variance
of the regression parameter estimate, adaptive cluster sampling is better than
simple random sampling. Adaptive sampling plans are also satisfied for habitat
association analysis with imperfect detectability. / Graduation date: 1995
|
24 |
Cumulative effects of land use on salmon habitat in southwest Oregon coastal streamsFrissell, Christopher Andrew, 1960- 30 April 1992 (has links)
As part of a hierarchical approach to classifying watersheds and stream habitats
based on geomorphic and geologic criteria, we defined ten classes of fluvial and
lacustrine habitats at the scale of valley segments. Valley segments are landscape units
which encompass surface waters and the adjacent floodplains and hillslopes with which
they interact over time frames of thousands of years. They form a large-scale template
that constrains the character of aquatic habitat, controls the effects of disturbances in
riparian areas, and mediates responses of streams to upland and upstream events. The
regional distribution of valley segment types in southwest Oregon reflects bedrock
geology and tectonic history of the landscape. Fluvial segment types differ in stream adjacent
landforms, slope erosion processes, floodplain and valley morphology, channel
slope, riparian vegetation, streambank texture, gravel bar morphology, and pool-forming
features. Studies that do not carefully account for inherent differences between valley
segment types could fail to detect critical changes in stream habitat caused by human
disturbance. Alluvial valley and alluviated canyon segment types, which have extensive
floodplains, low channel slopes, abundant woody debris, and ample gravel beds, are of
greatest direct importance for salmon and other native fishes. Virtually all alluvial valleys
in the study area have been heavily disturbed by logging, agriculture, and residential
development. Alluviated canyon segments located in the few drainage basins where
human activity has been limited probably serve as habitat refugia for the last diverse
assemblages and productive populations of salmon in the region. Alluviated canyons in
extensively-fogged basins exhibit increased abundance of large woody debris, fewer
cross-channel debris jams, more extensive bank erosion, reduced pool area and
increased riffle area, shallower riffles, and increased surface concentration of fine
sediments in pools and other habitats, compared to similar segments in lesser-disturbed
basins. These changes in channel morphology and stability appear to be driven by
increased sediment load, caused by logging-related landslides and other erosion
sources. Field studies in Sixes River basin indicated that abundance and diversity of
salmonid fishes declines as maximum stream temperature increases. Changes in
summer distribution of juvenile chinook and coho salmon since 1970 are related to
changes In water temperature. Although some tributaries have cooled, a decline in
rearing distribution in mainstem areas could be caused by long-term loss of channel
complexity and associated coolwater refugia. Analysis of fish habitat structures
constructed by federal and state agencies indicated that failure rates are high. Recovery
of anadromous fish runs in southwest Oregon will require protection of remaining habitat
refugia and reduction of sediment yield from disturbed watersheds. / Graduation date: 1992
|
25 |
The ecological and evolutionary assembly of competitive communities in dynamic landscapes /Pillay, Pradeep. January 2006 (has links)
We use metapopulation models based on a classic competition-colonization trade-off in order to (1) study community responses to spatially structured habitat loss on dynamic landscapes when species are assembled by ecological (biogeographic) processes; and (2) to study how species are assembled into communities by evolutionary mechanisms. In the first part of our study we show how the response of species richness to habitat destruction in dynamic landscapes can be driven by the existence of either the spatial structure of habitat dynamics or by life-history trade-offs among species. In the second part of our study we confirm that competitive trade-off models predict runaway evolution towards stochastic extinction, making it impossible for stable multispecies assemblages to evolve. We demonstrate that by relaxing the strict deterministic nature of competitive exclusion in such models species can avoid selection towards extinction, allowing for the possibility of species co-evolution resulting in stable multispecies assemblages.
|
26 |
Foraging behaviour and habitat use in the European starling, Sturnus vulgaris, in an agricultural environmentWhitehead, Siân Carolyn January 1994 (has links)
Recent changes in agricultural practice have reduced the diversity of habitats for a number of bird species, including the European Starling Sturnus vulgaris. I investigated the distribution of a starling population on farmland, and related this distribution to the availability of suitable habitats by studying the foraging behaviour of individual birds. I observed a preference of the overwintering flock for established pasture fields, particularly those which were closer to the central roost, which had shorter grass and which provided feeding areas further from hedges. I also demonstrated the role of leatherjacket Tipula paludosa availabilities in influencing the starlings' choice of feeding site. These prey were shown experimentally to be preferred over earthworms Lumbricus spp. which were the other main type of invertebrate prey available. I was unable to detect any systematic temporal pattern of habitat use which could have been linked to an appropriate theoretical framework (e.g. Ideal Free Distribution). I investigated the impact of starling foraging on prey availability by observing the behaviour of captive starlings allowed to forage in small enclosures. These experiments indicated that, at the level of foraging pressure expected in natural flocks, there was no significant resource depression during a single flock feeding visit to any one site. Furthermore I proposed that the extent of resource depression during the winter was insufficient to cause a shift in the birds' choice of foraging habitat over this period. The apparent lack of effects of resource depression raised the question of why starlings did not feed in the most preferred fields all the time. Further enclosure experiments investigated how an individual's foraging success might be affected by feeding with conspecifics. I found no evidence for enhancement or depression of foraging success as a result of feeding where another bird had just previously foraged, and little evidence for an effect of feeding in the presence of two other birds, despite changes in vigilance and time spent fighting. A possibly greater heterogeneity of these effects when in the natural flock situation was considered in relation to the observed flock departures. These and other effects (e.g. sampling the environment) were discussed as possible causes for the observed flock movements between fields. A final enclosure experiment investigated the impact of starling foraging on prey availability during the breeding season and demonstrated significant resource depression in a preferred field over the chick-feeding period. I then discussed starling foraging and the availability of suitable habitats in relation to the documented population decline of this species.
|
27 |
Use of radiotelemetry and GIS to distinguish habitat use between Graptemys ouachitensis and G. geographica in the Scioto RiverTemple-Miller, Kathleen G. January 2008 (has links)
Thesis (M.S.)--Ohio University, August, 2008. / Title from PDF t.p. Includes bibliographical references.
|
28 |
Wildlife response to spatial and temporal changes in forest habitatRittenhouse, Chadwick D. January 2008 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2008. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on June 15, 2009) Vita. Includes bibliographical references.
|
29 |
An environmental gradient model predicts the spatial distribution of potential habitat for Hypogymnia duplicata in the Cascade Mountains of northwestern Washington /Lesher, Robin. January 2005 (has links)
Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 59-63).
|
30 |
Graph-theoretic modeling of functional habitat connectivity for linx on the Okanogan Highlands, northern WashingtonJones, Aaron Paul. January 2004 (has links) (PDF)
Thesis (M.S.)--Montana State University--Bozeman, 2004. / Typescript. Chairperson, Graduate Committee: Richard J. Aspinall. Includes bibliographical references (leaves 129-146).
|
Page generated in 0.0707 seconds