Short-Term Forest Management Effects on a Long-Lived Ectotherm

Timber harvesting has been shown to have both positive and negative effects on forest dwelling species. We examined the immediate effects of timber harvests (clearcuts and group selection openings) on ectotherm behavior, using the eastern box turtle as a model. We monitored the movement and thermal ecology of 50 adult box turtles using radiotelemetry from May–October for two years prior to, and two years following scheduled timber harvests in the Central Hardwoods Region of the U.S. Annual home ranges (7.45 ha, 100% MCP) did not differ in any year or in response to timber harvests, but were 33% larger than previous estimates (range 0.47–187.67 ha). Distance of daily movements decreased post-harvest (from 22 m±1.2 m to 15 m±0.9 m) whereas thermal optima increased (from 23±1°C to 25±1°C). Microclimatic conditions varied by habitat type, but monthly average temperatures were warmer in harvested areas by as much as 13°C. Animals that used harvest openings were exposed to extreme monthly average temperatures (~40°C). As a result, the animals made shorter and more frequent movements in and out of the harvest areas while maintaining 9% higher body temperatures. This experimental design coupled with radiotelemetry and behavioral observation of a wild ectotherm population prior to and in response to anthropogenic habitat alteration is the first of its kind. Our results indicate that even in a relatively contiguous forested landscape with small-scale timber harvests, there are local effects on the thermal ecology of ectotherms. Ultimately, the results of this research can benefit the conservation and management of temperature-dependent species by informing effects of timber management across landscapes amid changing climates

A Decision Tool to Identify Population Management Strategies for Common Ravens and Other Avian Predators

Some avian species have developed the capacity to leverage resource subsidies associated with human manipulated landscapes to increase population densities in habitats with naturally low carrying capacities. Elevated corvid densities and new territory establishment have led to an unsustainable increase in depredation pressure on sympatric native wildlife prey populations as well as in crop damage. Yet, subsidized predator removal programs aimed at reducing densities are likely most effective longer-term when conducted in tandem with subsidy control, habitat management, and robust assessment monitoring programs. We developed decision support software that leverages stage structured Lefkovitch population matrices to compare and identify treatment strategies that reduce subsidized avian predator densities most efficiently, in terms of limiting both cost and take levels. The StallPOPd (Version 4; available at https://doi.org/10.7298/sk2e-0c38.4) software enables managers to enter the area of their management stratum and the demographic properties (vital rates) of target bird population(s) of interest to evaluate strategies to decrease or curtail further population growth. Strategies explicitly include the reduction in fertility (i.e., eggs hatched) and/or the culling of hatchlings, non-breeders and/or breeders, but implicitly comprise reduction in survival or reproduction through subsidy denial. We illustrate the utilities of the software with examples using common ravens (Corvus corax; ravens) in the Mojave Desert of California, USA. Unfortunately, the survival and reproduction effects of each unit of a particular subsidy in that system have remained elusive, though this is the priority of current research. Because the software leverages a life history representation that is known to characterize hundreds of wildlife species in addition to ravens, the work expands the suite of tools available to wildlife managers and agricultural industry specialists to abate bird damage and impacts on sensitive wildlife in habitats with persistent human subsidies

Burmese pythons in Florida: A synthesis of biology, impacts, and management tools

Burmese pythons (Python molurus bivittatus) are native to southeastern Asia, however, there is an established invasive population inhabiting much of southern Florida throughout the Greater Everglades Ecosystem. Pythons have severely impacted native species and ecosystems in Florida and represent one of the most intractable invasive-species management issues across the globe. The difficulty stems from a unique combination of inaccessible habitat and the cryptic and resilient nature of pythons that thrive in the subtropical environment of southern Florida, rendering them extremely challenging to detect. Here we provide a comprehensive review and synthesis of the science relevant to managing invasive Burmese pythons. We describe existing control tools and review challenges to productive research, identifying key knowledge gaps that would improve future research and decision making for python control. (119 pp

Effects of forest management on the ecology and behavior of Eastern Box Turtles

Declines in long-lived and geographically widespread forest animals, such as the case with Eastern Box Turtles (Terrapene carolina carolina ), warrants investigation. Despite declines, this species\u27 ability to endure in a range of available habitat and its physiological ties to environmental flux make it ideal for study of habitat use and selection amid anthropogenic disturbances. For my thesis work, I focused on investigating the ecology and behavior of Eastern Box Turtles following timber harvests. As part of the Hardwood Ecosystem Experiment, I used nine experimental forest management sites to investigate the effects of clearcut harvest openings and group selection harvest openings on box turtles. I used standard homing radiotelemetry to collect GPS location, morphometric, temperature, and behavior data on 50 adult Eastern Box Turtles. I conducted the majority of this work during the active seasons (May–October) but during the winter of 2010 I investigated the hibernal thermal ecology within clearcut harvest openings. Combined with the radiotelemetry data previously collected on these turtles from 2007-08, I was able to measure the effects of the harvests by analyses of movement parameters and temperatures. I found that timber harvests had no effect on the typical measurement of home range size, 100% Minimum Convex Polygons (MCP), however the MCPs here are 33% larger than any other published report for this species. Additionally, I found that turtles decreased the daily distances they traveled by approximately 30%, but their thermal optima increased by 8% following the harvests. Microclimates inside the timber harvests were significantly warmer (29%) in the summer and colder (31%) in the winter than forested habitats, effectively excluding many animals from consistently using them. Instead of leaving the harvested areas, however, turtles continued to use them differently. During the active season, box turtles used the edges of harvest areas apparently for behavioral thermoregulation and possibly for foraging. Turtles that used the harvest areas maintained 9% higher body temperatures during the active season than those that did not. During the winter, turtles generally burrowed to 10 cm for overwintering, but depth varied by slope and gender. I found that the depth influenced the emergence timing, which was also correlated with a soil-surface temperature inversion. A single female turtle that hibernated in a group-selection harvest opening had an estimated burrowing depth of nearly 30 cm to maintain her hibernal body temperature. Moreover, I estimated the annual survival rate (96.2%) of box turtles in our population, the first for the Midwest. The investigation of ecological mechanisms underlying species declines has become paramount in conservation literature. Simply reporting the extirpation of populations without testing mechanistic causes does little to promote conservation management. Herein, I investigated temporal thermal habitat availability, habitat use, thermal behavior, survival, and intersexual differences among Eastern Box Turtles within the framework of a managed forest setting

Habitat and Animal Temperature Ranges.

<p>Mean monthly temperature maxima (Tmax), mean (Tmean), and minima (Tmin) over two years (2009–2010) by habitat type (clearcut openings, group selection openings, harvest-adjacent forest (Harv. Adjacent), and forested control) (a). Maxima, means, and minima monthly eastern box turtle body temperatures (Tb) for the same period (b).</p

Published studies involving home range estimates from native populations of <i>T. carolina.</i>

<p>Published studies involving home range estimates from native populations of <i>T. carolina.</i></p

Thermal Optima.

<p>Scatter plot of daily distances traveled by eastern box turtles (steplengths; y-axes) by ground temperature (T_g in °C; x-axes). All 2007–10 steplengths (in meters per day) by ground temperature (a.) and the log-transformed steplength by ground temperature (b.). Pre-harvest (2007–08) steplength in meters per day by ground temperature (c.) and post-harvest (2009–10; d.). Plots show 95% (black ellipse) and 50% (grey ellipse) density ellipses around points and histogram densities along plot boarders. Darkened areas represent the peak of activity temperatures (22–26°C; thermal optimum) in these data.</p

Pre vs. Post Movements.

<p>Average steplength (m/day) moved by eastern box turtles each month for both harvest periods (pre-harvest [2007–08] and post-harvest [2009–10]; bars). The average ground temperatures (Tg; °C) recorded at turtle location each harvest period are also plotted (lines).</p

Pre-harvest (Pre-harv.; 2007–2008) and post-harvest (Post-harv.; 2009–2010) home ranges of female and male eastern box turtles.

*<p>The associated management class (Mngmnt Class).</p>†<p>biennial Minimum Convex Polygons (MCP) home ranges.</p>‡<p>Only the 95% kernel isopleths areas are listed here, as they are the only relevant comparisons to 100% MCP.</p