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Student Award FinalistsEach year, SCB administers a Student Awards program, with prizes that include cash and books. All student authors of 15-minute contributed papers are eligible to enter the award competition. Jami Barnes Bowling Green State University, Bowling Green, Ohio, USA Linking population viability analysis and habitat suitability for the conservation of Audubon’s Crested Caracara (Caracara cheriway) in Florida Florida’s rapidly growing human population creates an urgent need to prioritize land use to reconcile the needs of humans and native species particularly when species of conservation overlap with anthropogenic land use. We used GIS analyses and population viability analyses to address questions regarding the conservation needs of the Audubon’s Crested Caracara, (Caracara cheriway), an opportunistic raptor endemic to Florida. This species is of particular concern because over 80 of known nesting locations occur on private lands. Using information from both the literature and field surveys, we constructed a spatially-explicit, stochastic population viability model to determine the most important demographic parameters for the Caracara, assess viability, and identify criteria for potential habitat. The most important demographic variable impacting viability was adult survival, and our spatially-explicit model indicated that the Caracara population in Florida is stable under current conditions, assuming no future changes. However, if nesting locations on private lands are not maintained our model indicated quasi-extinction. We also found that 5 of the 43 land cover types (e.g., Hardwood Hammocks) identified in Florida are significantly associated with home ranges. This approach provides a means of addressing conservation concerns for species at risk, especially those occurring primarily on private lands. Megan Gahl University of Maine, Orono, Maine, USA Amphibian disease: can landscape features of breeding pools distinguish wetlands at risk? From 1999–2001 in Acadia National Park (ANP), Maine, USA, tadpole die-off events occurred in various small wetlands. Disease events in ANP are unique in their temporal and spatial variability, diversity of pathogens (Ranavirus spp., Ichthyophonus spp., Perkinsus-like organism) and multiple amphibian species affected: wood frogs (Rana sylvatica), green frogs (Rana clamitans), bullfrogs (Rana catesbeiana), and spring peepers (Pseudacris crucifer). We examined landscape attributes of 57 amphibian breeding wetlands of varying hydrology, size, amphibian community, and disease history to determine if there were features specific to wetlands which harbored amphibian die-off events. We developed and evaluated models using logistic regression and model selection criterion (QAICc). High slope position was the most important predictor of amphibian disease, and was present in all competing models. Results also indicated that sites with western aspect and those without a permanent outlet may affect disease susceptibility, suggesting an influence from atmospheric deposition. Conservation and disease containment efforts in ANP should be directed toward higher slope wetlands, especially isolated wetlands without outlets, such as vernal pools. While conservation strategies directly influence ANP wetland management, the diseases and amphibian species present in ANP are widespread and therefore conservation strategies may be instructive for monitoring and conservation efforts elsewhere. Elizabeth Harper University of Missouri, Columbia, Missouri, USA Demographic consequences of buffer zone diameter for pond-breeding amphibian populations Pond breeding amphibians depend on terrestrial as well as aquatic habitat to maintain viable populations. Some states have begun to develop criteria for maintaining terrestrial buffer zones around wetlands, however determining the appropriate diameter has been difficult. Estimates based on data from the literature suggest that core terrestrial habitat for amphibians extends up to 290 m from the shoreline. This area includes 95% of the adult population, however the question most often asked by land managers is what is the minimum terrestrial area necessary to maintain a viable population? Using data available in the literature we constructed a stochastic stage-based matrix population model to determine the potential impacts of different sized areas of core terrestrial habitat on the population growth rate and time to extinction for populations of pond-breeding frogs. We found that buffer diameter influenced the probability of extinction of local populations, with extinction probabilities as much as six times greater for populations with buffer zones of 150 m than 1000 m. Although it is not possible to determine the exact buffer zone diameter that will ensure population persistence, our models demonstrate the demographic consequences of insufficient terrestrial habitat and highlight areas of research necessary for more accurately delineated buffer zones. Wendy Kuntz University of Hawaii, Honolulu, Hawaii, USA Identifying non-breeding habitat in mobile species: seasonal elevational movement in a Hawaiian honeycreeper In Hawaii, endemic forest bird management currently focuses on the habitat protection of high-elevation areas (1530 m). Breeding bird surveys find that most species are nearly extirpated from low-elevation habitat, likely due to introduced mosquito-borne disease. However, little is known about non-breeding behavior, movement, and habitat in the potentially mobile species, including the ’I’iwi (Vestiaria coccinea). To begin to address these questions, I fitted individual ’I’iwi from a high elevation (1920 m) breeding population on the eastern slope of Mauna Kea with radio-transmitters and tracked movements using ground and aerial telemetry. A total of 69 ’I’iwi were fitted during 2003 and 2004; of these, 37 were detected away from the breeding site (1 km). Non-breeding season movement had strong directional and elevational components and, in both years, nearly 50 of the detection points were in mid-elevation (900-1530 m) habitat. Although previously unrecognized, the mid-elevation forest is an important non-breeding habitat for high-elevation populations. Long-term high-elevation population persistence most likely will depend on mid-elevation forest resource protection and management, necessitating cross-agency and private landowner cooperation. These results demonstrate that an understanding of the non-breeding behavior of mobile species is critical for appropriate long-term conservation planning. Carolyn Kurle University of California, Santa Cruz, California, USA Introduced rats indirectly transform island intertidal communities Invasive species on islands are known to have direct deleterious effects on native species primarily through predation. Examples of indirect, cascading effects are rarer, especially on a community-wide, landscape level. The introduction of rats (Rattus norvegicus) onto many of the Aleutian Islands in Alaska provides an opportunity to conduct a large-scale natural experiment to test for differences between invaded and non-invaded islands. I tested the hypothesis that, through chick predation, introduced rats significantly limit the number of marine birds that forage in the intertidal. Thus, intertidal invertebrates are released from heavy foraging pressure by the birds. It was expected that an increase in herbivory by higher numbers of invertebrates would cause reductions in fleshy algal cover further altering the intertidal community. I surveyed the rocky intertidal on several Aleutian Islands (8 with rats and 15 without) during summers 2002–2004 and analyzed USFWS survey data to assess differences in bird densities between islands. Herbivorous invertebrates were significantly higher on islands with rats while the percentage of intertidal area covered by fleshy algae was half that of islands without rats. Densities of birds that forage in the intertidal are an order of magnitude lower on islands with rats. My results demonstrate a rare example of a landscape level trophic cascade induced by an invasive terrestrial predator with repercussions into a marine community. Daniel McGarvey University of Alabama, Tuscaloosa, Alabama, USA The "power" of science: confronting Type II error under the Endangered Species Act In conventional research and hypothesis testing, the benefit of doubt belongs to the null hypothesis, while the burden of proof rests with the alternative hypothesis. This conservative paradigm, which stems from the institutional assumption that Type II error (i.e., failing to detect a significant effect) is preferable to Type I (i.e., erroneously claiming a significant effect), is prudent when the scientific community can afford to replicate experiments many times. It can break down in endangered species management, however, when officials must make decisions with only the "best available data," and a Type II error may permit extinction. Accordingly, I argue that power analysis, which provides unbiased estimates of Type II error probability, should be instituted in all Endangered Species Act reviews. To substantiate this claim, I apply power analysis to a recent review of endangered species management in the upper Klamath Basin (southern Oregon), in which a failed hypothesis test was used as evidence against the need for protective action, despite the fact that Type II error probability exceeded Type I by an approximately 12x margin. I then conclude that hypothesis tests are an adequate basis for endangered species decisions only when they incorporate sufficient statistical power. Jeff Milder Cornell University, Ithaca, New York, USA Assessing the conservation benefits of sensitive land development In the United States, innovative approaches to land development such as limited development projects and conservation subdivisions have been advanced as a way to conserve nature while meeting human demands for development; yet, there has been little critical evaluation of the conservation effectiveness of these practices. To address this deficiency, we created a multi-criteria evaluation method that uses a coarse filter and mesofilter approach to measure the conservation success of such integrated land use projects. The method’s eight indicators quantify a project’s positive and negative impacts to terrestrial and aquatic ecosystems on the site and in the larger landscape. We used this method to assess ten conservation and limited development projects in the eastern United States that were conducted or facilitated by conservation land trusts. The assessment revealed that these projects cost-effectively protected unique and threatened resources, including rare species and ecological communities. It also underscored the method’s utility for helping conservationists, developers, and land use planners to design, improve, and evaluate integrated land use projects that contribute meaningfully to conservation. David Patrick University of Maine, Orono, Maine, USA Effects of forest harvesting on juvenile amphibian dispersal In 2004 and 2005, we studied the effects of forestry on juvenile wood frog dispersal in Maine. Four landscape-scale replicates of four forestry treatments were centered on breeding ponds. A total of 8632 emerging juvenile wood frogs were captured at encircling drift fences and marked. Animals were recaptured at drift fence/pitfall arrays at 16, 50, 100, and 150 m from the ponds. The results indicate that juvenile wood frog select higher quality habitat when dispersing although all treatments showed similar patterns in temporal captures. This selection reduces density in poorer quality habitats such as clearcuts. Clearcuts do not reduce landscape permeability for juvenile wood frogs, however, and appear to be suitable habitat, albeit of a lesser quality. The highest abundance of juvenile wood frogs settled at a distance of 100 m. This result is contrary to many dispersal models where the highest frequency of dispersers is found closest to the source, and may have important implications when defining the minimum area of terrestrial habitat required for amphibian populations. Our study forms the first landscape-scale evaluation of how forest treatments influence juvenile amphibian dispersal, and provides evidence that both density of con-specifics and habitat quality can influence dispersal of juvenile amphibians. Ryan Sensenig University of California, Davis, California, USA Spatial ecology of fire in an East African savannah: effects of burn size and patchiness on the foraging ecology of grazers of varying body size Maintaining habitat heterogeneity is frequently cited as vital to conservation. Ecologists are increasingly aware that an animal’s perception of heterogeneity is scale dependent. Although body size scaling laws have been explored theoretically to explain the coexistence of consumers sharing the same resources, there have been few landscape level manipulations testing these assumptions. We implemented a landscape level prescribed burning project in an Acacia savannah in Laikipia Kenya in order to better understand how herbivores of varying body size respond to habitat heterogeneity at different scales. In 2004 and 2005 we burned more than 470 hectares across 18 plots varying in their extent (1, 9, and 81 ha) and their burn pattern (continuous, patchy, and unburned) to create a complete factorial design. Across all burned sites we found a significant negative relationship between body size and preference for burned sites as measured using dung counts. MANOVA of dung counts from herbivores ranging in body size from hare to elephant indicated overall significant effects of both burn extent and burn patchiness. Consistent with scaling theory we found high similarities between body size and preferred patch size. Maximizing diversity of herbivores sharing the same resources requires explicit attention to the scale of heterogeneity. Jennifer Solomon University of Florida, Gainesville, Florida, USA Polling for poachers: testing a unique method for estimating illegal resource use in protected areas Illegal resource use is considered a major threat to conservation in protected areas throughout the world, yet accurately estimating the number of poachers has been difficult. People violating the law often do not identify themselves for fear of retribution and thus effectively quantifying illegal resource use is limited by methodological constraints. I explore the effectiveness of the randomized response technique (RRT) with a population that is largely illiterate to assist park management in assessing the extent of illegal resource use at Kibale National Park, Uganda. RRT is unique in allowing respondents to disclose sensitive information because the interviewer can not ascertain an individual’s true response to the incriminating question. I found estimates of illegal resource use when measured via RRT significantly higher than when measured by direct questioning for all resources. For example, when directly questioned only 2.5 of the 251 people surveyed admitted to illegally extracting charcoal, while RRT estimated that 51.6 collected charcoal. This study takes the first step toward developing and testing a potentially powerful tool for conservation priority setting and programmatic evaluation in a developing world setting. Christopher Stallings Oregon State University, Corvallis, Oregon USA Indirect effects of fishing on coral-reef fish communities Changes in relative abundance and shifts in dominance of top trophic-level species may have strong top-down effects on the abundances of other species and on community structure. Throughout the greater Caribbean, intense fishing has depleted populations of Nassau grouper (Epinephelus striatus), while populations of the unfished coney grouper (Cephalopholis fulva) have proliferated, possibly due to moderated negative interactions between the two species. I experimentally tested the effects of these two groupers on recruitment of coral reef fishes to spatially isolated reefs in the Bahamas. Total recruitment was 2.65 times higher on reefs occupied by Nassau grouper and on control reefs with no grouper than on reefs occupied by coney grouper. Significantly higher recruitment of four common species occurred on Nassau grouper and control reefs. These results show that different species of top trophic-level predators can have profoundly different effects on lower trophic levels. In particular, overfishing of Nassau grouper allows coney grouper to have strong negative impacts on recruitment of other coral reef fishes. To strengthen marine conservation efforts and increase the sustainability of fished populations, fisheries management should include both the direct and indirect effects of fishing on marine communities. Mya Thompson Cornell University, Ithaca, New York, USA Applied acoustic monitoring: African forest elephant population estimates from Kakum National Park, Ghana Acoustic monitoring has been suggested as an alternative survey technique for vocal taxa living in habitats not conducive to visual surveys. This study applied a model for estimating abundance of African forest elephants (Loxodonta cyclotis) from calling rates to acoustic data from Kakum National Park, Ghana. Kakum harbors a small, closed population of forest elephants. Nine acoustic sensors randomly distributed throughout the 366 km2 park continuously gathered data for three months. Extracted call rate data were used to estimate local abundance of elephants. A sound propagation model was used to estimate an effective detection radius for the acoustic sensors and extrapolate the abundance estimate to unsampled areas. The resulting estimate falls within the confidence bounds of estimates from recent dung transect surveys suggesting that calling rate is an appropriate index of abundance for African forest elephants. Because acoustic surveys can gather data from larger areas and over longer periods, confidence intervals around population estimates are narrower than those gained from traditional dung transect methods. This study provides the first validation of acoustic techniques to estimate abundance and may prove valuable in other wildlife monitoring efforts. | |||||||||||||||||
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