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SPATIAL ECOLOGY OF SNAPPING TURTLE (CHELYDRA SERPENTINA) WITHIN AN URBAN WETLAND COMPLEXZachary Robert Kellogg (11559850) 22 November 2021 (has links)
The
conversion of natural habitat to urban areas has lasting impacts on wildlife
and biodiversity. Known effects to urban wildlife include direct mortality
while crossing roads, reduced species diversity, and habitat fragmentation and degradation.
Among wildlife occupying urban areas, turtle populations can be particularly
impacted in anthropogenic landscapes. Snapping Turtle (<i>Chelydra serpentina</i>)
is one of the most common species found within urban wetlands, but populations
are beginning to show declines in northern portions of their geographic range.
The preservation and management of this species is aided by knowledge related
to its spatial ecology. I investigated <i>C.
serpentina</i> home range, movement, habitat use, and habitat selection in a midwestern
USA urban wetland complex during two active seasons (May-August 2019 and 2020)
using radiotelemetry. Home range sizes and movement did not differ between sex
or sample year except the mean movement of males decreased from 2019 to 2020.
No differences in mean monthly movement were found between sexes but mean
monthly movement did differ between month and year. Habitat use was skewed
during the active season and did not differ between sex or year, but there were
positive habitat associations between forested wetlands and modal centers of
activity (MCA). Habitat selection was tested at two spatial scales by comparing
random points to home ranges and turtle locations using Euclidean Distance
Analysis. Turtles appeared to select home ranges from available habitat site-wide
but did not select habitat within home ranges. Home range selection included
semi-permanent open water, trail, road/barrier, permanent open water, scrub-shrub,
ditches, shoreline, and vegetated ponds, while upland forest, field and
agriculture habitat were avoided. Home ranges appear to be constrained by
available habitat and movement differences between years may be due to anthropogenic
change in water levels. The use of space seems to be more affected by wetland
size and connectivity than proximity to barriers, which suggests that
management practices that protect turtles from accessing roads and railways
will benefit populations. Additionally, habitat selection and association
indicate that ditches are utilized as corridors between wetland areas. When
feasible, increasing the connectivity of large wetlands containing many habitat
types should have positive impacts on the persistence of populations in human
dominated landscapes.
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Bat Community Structure and Habitat Selection Across an Urban-Agricultural LandscapeGalen Edward Burrell (13171299) 29 July 2022 (has links)
<p> </p>
<p>Bats serve important ecological and economic roles in their communities. However, due to anthropogenic land use and human-introduced disease, bat populations in North America are facing unprecedented declines. To better inform conservation efforts for bat species in northeastern Indiana, I studied two aspects of bat ecology: (1) the effects of urbanization and agriculture on bat community composition in northeastern Indiana and (2) the roosting behavior of a population of state endangered/federally threatened northern long-eared bats (<em>Myotis septentrionalis</em>; hereafter northern myotis) in a restored mesic forest adjacent to a moderately sized city (Fort Wayne, IN). To study the first aspect, I deployed acoustic detectors in green spaces throughout Fort Wayne and the surrounding rural areas of Allen County. For each detector site, I compared species occupancy rates with site-specific characteristics at the plot scale (e.g., % canopy cover, midstory density) and at multiple landscape scales (e.g., % impervious cover within 1 km). Across 429 survey nights, acoustic detectors recorded calls from eight unique bat species, of which six species were abundant enough to conduct occupancy modeling. In four of the six species, measures of the amount of forest and forest edge in the landscape were included in one or more of the top models. The top models for the two other bat species, tricolored bats (<em>Perimyotis subflavus</em>) and silver-haired bats (<em>Lasionycteris noctivagans</em>), included measures of urban land cover and revealed a negative relationship between probability of occupancy and the proportion of high-density urban land in the area. The effect of habitat scale also differed between species. For example, models in the confidence set for eastern red bats (<em>Lasiurus borealis</em>) included variables associated with the plots surrounding detectors and with landscape features within 100 m of detectors. In contrast, the top models for hoary bats (<em>Lasiurus cinereus</em>) included landscape features at larger scales, within 500m and 1 km of detector sites. These findings suggest that both generalist and forest-obligate bat species in this study area selected spaces with greater levels of forested habitat. Furthermore, heavily urbanized areas were less likely to support the same levels of bat diversity as areas with forests and other green space.</p>
<p>To accomplish the second aspect of my project, I captured bats in Fox Island County Park (Fort Wayne, IN) using mist-nets and affixed temperature-sensitive radio transmitters to four northern myotis individuals. I tracked these individuals back to day roosts, where I recorded roost characteristics (e.g., tree height, # of roost trees within 0.1 ha) and monitored bat skin temperatures (Tsk). I compared the characteristics of selected roosts to those of randomly assigned available trees in the same landscape to determine trends in roost selection preferences. Northern myotis in this study strongly preferred standing dead trees within a 31-ha patch of flooded forest on the northern border of Fox Island. These trees were highly exposed to solar radiation and were consistently warmer than ambient weather conditions, which suggests they may provide important thermoregulatory benefits to reproductive females and other members of the population.</p>
<p>My research offers valuable information regarding resource use by bat communities in a landscape dominated by anthropogenic development. Urban areas containing large stretches of forests with trees in various stages of decay will be more likely to meet the needs of bats that would otherwise struggle in developed landscapes. The results of this study can be used to inform conservation efforts aimed at protecting populations of bats throughout Indiana and the Midwestern United States.</p>
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