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Evaluating artificial shelter arrays as a minimally invasive monitoring tool for the hellbender (Cryptobranchus alleganiensis)
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Hellbenders Cryptobranchus alleganiensis are critically imperiled amphibians throughout the eastern USA. Rock-lifting is widely used to monitor hellbenders but can severely disturb habitat. We asked whether artificial shelter occupancy (the proportion of occupied shelters in an array) would function as a proxy for hellbender abundance and there by serve as a viable alternative to rock-lifting. We hypothesized that shelter occupancy would vary spatially in response to hellbender density, natural shelter density, or both, and would vary temporally with hellbender
seasonal activity patterns and time since shelter deployment. We established shelter arrays (n = 30 shelters each) in 6 stream reaches and monitored them monthly for up to 2 yr. We used Bayesian mixed logistic regression and model ranking criteria to assess support for hypotheses concerning drivers of shelter occupancy. In all reaches, shelter occupancy was highest from June–August each year and was higher in Year 2 relative to Year 1. Our best-supported model indicated that the extent of boulder and bedrock (hereafter, natural shelter) in a reach mediated the relationship between hellbender abundance and shelter occupancy. More explicitly, shelter occupancy was positively correlated with abundance when natural shelter covered <20% of a reach, but uncorrelated with abundance when natural shelter was more abundant. While shelter occupancy should not be used to infer variation in hellbender relative abundance when substrate composition varies among reaches, we showed that artificial shelters can function as valuable monitoring tools when reaches meet certain criteria, though regular shelter maintenance is critical.
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Artificial Nest Box Research
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The use of nest boxes by the hellbender salamander in Western North Carolina
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The hellbender salamander (Cryptobranchus alleganiensis) is a unique, large-bodied amphibian that serves as an excellent water quality indicator species in Western North Carolina. This animal has suffered substantial population declines over the past four decades throughout its range. Increased stream siltation largely attributed to human development fills the concave undersides of large rocks, consequently destroying hellbender breeding habitat. Habitat degradation has contributed to reductions in North Carolinian populations to such a degree that the species is now considered of Special Concern in the state. In order to restore hellbender population sizes under current land use conditions, researchers have recently begun developing artificial nest boxes that exclude sediment and promote increased reproduction. To identify the short-term efficacy of these shelters as substitutes for natural hellbender habitat in Western North Carolina, I constructed and placed 54 boxes across five river sites throughout the region. Following summer nest box installment, I examined each shelter through the breeding season for hellbender in habitation and to determine the quality of water passing through the structures. Additionally, I created a maximum entropy species distribution model and conducted a spatial connectivity analysis for the hellbenders of Western North Carolina to identify ideal locations for nest boxes installation in the future. Although no hellbenders have yet been detected in the artificial shelters, additional structural improvements and time may reveal nest boxes to be useful conservation tools for this iconic species of Special Concern.
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Artificial Nest Box Research
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Movement and habitat use of Eastern hellbenders (Cryptobranchus alleganiensis alleganiensis) following population augmentation
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With amphibian declines at crisis levels, translocations, including population augmentations, are commonly used for amphibian conservation. Eastern Hellbenders (Cryptobranchus alleganiensis alleganiensis) have declined to low densities in many areas of their range, making them ideal candidates for population augmentation. Both wild adults and captive-reared juveniles have been used for augmentations, but their suitability has never been directly compared. Herein, we use radio telemetry with Eastern Hellbenders to examine patterns of site fidelity, movement, and habitat use over a 2-yr period for adult residents, wild adult translocates, and captive-reared juvenile translocates. We used generalized linear models and generalized linear mixed models to identify temporal trends and explore the effects of residential status (resident vs. translocate) and origin/age (captive-reared juveniles vs. wild adults) on various ecological and behavioral traits relating to habitat. Site fidelity was high in adult residents and wild adult translocates, but lower in captive-reared juvenile translocates. Both adult and juvenile translocates had greater mean movement distances than residents, leading to larger home range sizes, but these differences decreased over time. Wild adult translocates had a higher probability of using artificial nest rocks than adult residents or captive-reared juvenile translocates. This pattern was most prevalent early in the study, indicating these shelters are particularly useful during the transition to release sites. Captive-reared juvenile translocates had lower site fidelity and utilized suboptimal habitat (smaller and fewer shelter rocks) compared to wild adults. Compared to previous studies, translocations had fewer negative effects on site residents or wild translocates and might be effective at promoting growth of Hellbender populations. However, translocations of captive-reared juveniles were less successful. As we are uncertain whether captive-rearing or ontogeny led to these differences, both longer head-starting times and conditioning should be explored to improve outcomes in captive-reared juvenile cohorts.
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Artificial Nest Box Research
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Theory and practice of the hydrodynamic redesign of artifical hellbender habitat
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The success of nest boxes in Missouri led researchers to test whether similar management tools could increase C. a. alleganiensis populations in the streams of western North Carolina, where these salamanders are listed as a Species of Special Concern (Messerman 2014). Fifty-four nest boxes were constructed following the boot-shaped design of Briggler and Ackerson (2012) in May 2013, and were installed across five known C. alleganiensis stream sites between late June and early August 2013. Messerman (2014) then monitored each nest box every three to four weeks through November 2013, and the boxes were revisited in August 2014 and July 2015 to observe structural condition and occupancy (Messerman, pers. obs.). Of the 54 nest boxes, only two structures at a single site were confirmed as inhabited in 2014 and 2015, and no breeding events were detected (Messerman, pers. obs.). Moreover, many of these ~50 lb concrete boxes moved in flood events or accumulated sediment at the downstream tunnel entrance (Messerman 2014). The low success of the boot-shaped nest box design in North Carolina may be attributed to the sites generally being narrower and shallower than those in Missouri, with much of the substrate consisting of bedrock slabs covered by relatively thin layers of rock, gravel and silt. Here we address the observed shortcomings of the original North Carolina design through the lens of engineering, and present a new and easily implemented nest box model for use in streams like those found in western North Carolina.
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Artificial Nest Box Research
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Outcomes from Delivery of NRCS's WLFW-Bobwhite in Managed Pine Savannahs
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In 2016, the Natural Resources Conservation Service’s Working Lands for Wildlife partnership began funding management activities designed to enhance, restore, and protect bobwhites habitat on private lands. Through the WLFW program, NRCS is able to assist landowners to voluntarily create and maintain bobwhite habitat in order to support the range-wide recovery of the species. In 2018, NRCS entered into an agreement with the University of Georgia to assess habitat outcomes and bobwhite population response to our conservation actions.
n collaboration with the University of Georgia, NRCS is now looking to monitor some of these managed lands to help tease out habitat features that promote excellent bobwhite habitat. If possible, additional information (e.g., other forestry management actions employed) may also be collected through interviews with landowners and/or conservation partners.
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WLFW Outcomes: Funded Research
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Assessment of Native Grasses for Forage & Bobwhite Habitat
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The University of Tennessee Institute of Agriculture, through its Center for Native Grasslands Management will conduct a study to evaluate the effectiveness of a working lands conservation model for enhancing northern bobwhite and other grasslands wildlife populations. Specifically, we will evaluate native grass forage production within fescue-belt landscapes to determine how effective this strategy is for improved survival and productivity of northern bobwhite and abundance of associated grassland bird species. The study will be conducted in cooperation with partner agencies within the fescue belt.
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WLFW Outcomes: Funded Research
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Economic and Production Performance of Native Grasses as Forage in the Fescue Belt
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The primary purpose of developing this literature review and summary was to inform producers about the potential benefits from utilizing warm-season grasses in the Fescue Belt. Effectively, managing forages is not always straightforward for livestock producers. Summarizing the economic and production benefits from using warm-season grasses could help producers make more informed forage management decision and might encourage producers to consider adopting warm-season grasses. Furthermore, this literature review also gathered information about the potential benefits of using native grasslands as forage to the quail population in this region, which could likely result in an economic benefit to the producer from leasing farmland to hunters.
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WLFW Outcomes: Funded Research
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USDA Agricultural Research Service National Programs
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ARS research is organized into National Programs. These programs serve to bring coordination, communication, and empowerment to approximately 690 research projects carried out by ARS. The National Programs focus on the relevance, impact, and quality of ARS research.
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General Resources Holdings
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USDA Regional Biomass Research Centers (RBRC)
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This USDA-led effort (RBRC), which is coordinated by ARS and the U.S. Forest Service, is tasked with ensuring that dependable feedstock supplies use agricultural and forestry feedstocks to produce advanced biofuels that meet legislated goals and market demand, and maximizing participation of U.S. rural areas in an emerging and profitable biofuels and biobased products economy.
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General Resources Holdings
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USDA Long-Term Agroecosystem Research Network
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The Long-Term Agroecosystem Research (LTAR) Network is a new network developing national strategies for the sustainable intensification of agricultural production.
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General Resources Holdings
