5 results on '"Magness, Dawn R."'
Search Results
2. EVALUATION OF SMALL UNMANNED AERIAL SYSTEMS AS A CENSUS TOOL FOR ALEUTIAN TERN ONYCHOPRION ALEUTICUS COLONIES.
- Author
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MAGNESS, DAWN R., ESKELIN, TODD, LAKER, MARK, and RENNER, HEATHER M.
- Subjects
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SEA birds , *TERNS , *DRONE aircraft , *COLONIAL birds , *BIRD population measurement - Abstract
Aleutian Tern Onychoprion aleuticus numbers in Alaska appear to be in decline; however, colonies are difficult to count for the purposes of monitoring due to their co-occurrence with Arctic Terns Sterna paradisaea, low nesting densities, high variability in attendance, sensitivity to human disturbance, and remote terrain. We paired visual observations with unmanned aerial systems (UASs) to test the feasibility of using this technology to survey a small colony of nesting Arctic and Aleutian terns in southcentral Alaska. We used counts of terns in the air and nest attendance to test for disturbance from UAS flights. We conducted 11 UAS flights over seven days at altitudes ranging from 15-30 m and located 23 nests in the 4.1 ha (0.041 km²) colony site (5.6 nests ha-1) by systematically searching the orthomosaics. We were most likely to distinguish tern species in the 18-m and 15-m altitude photos; the white forehead was most visible in side angle rather than top-down. Nest attendance and the number of aerial birds were not influenced by the UAS in this colony, which experiences high Larus gull activity. Aleutian Terns arrived on 19 May and were attending nests by 02 June; nest attendance declined throughout June. We believe the best approximation of total nesting pairs will be achieved by counting nests 7-10 d after first initiation. In mixed species colonies, we recommend that UASs fly in a 'lawn mower' pattern with overlap to maximize side angle images and aim for an image resolution of < 4 mm (which was achieved by 15-m altitude flights with our camera setup). In single species colonies, 30 m is sufficient and can be achieved more efficiently. [ABSTRACT FROM AUTHOR]
- Published
- 2019
3. Arthropod and oligochaete assemblages from grasslands of the southern Kenai Peninsula, Alaska.
- Author
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Bowser, Matthew L., Morton, John M., Hanson, John Delton, Magness, Dawn R., and Okuly, Mallory
- Subjects
TAIGAS ,ARTHROPODA ,CLIMATE change ,GRASSLANDS - Abstract
Background By the end of this century, the potential climate-biome of the southern Kenai Peninsula is forecasted to change from transitional boreal forest to prairie and grasslands, a scenario that may already be playing out in the Caribou Hills region. Here, spruce (Picea × lutzii Little [glauca × sitchensis]) forests were heavily thinned by an outbreak of the spruce bark beetle (Dendroctonus rufipennis (Kirby, 1837)) and replaced by the native but invasive grass species, Calamagrostis canadensis (Michx.) P. Beauv. As part of a project designed to delimit and characterize potentially expanding grasslands in this region, we sought to characterize the arthropod and earthworm communities of these grasslands. We also used this sampling effort as a trial of applying high-throughput sequencing metabarcoding methods to a real-world inventory of terrestrial arthropods. New information We documented 131 occurrences of 67 native arthropod species at ten sites, characterizing the arthropod fauna of these grasslands as being dominated by Hemiptera (60% of total reads) and Diptera (38% of total reads). We found a single exotic earthworm species, Dendrobaena octaedra (Savigny, 1826), at 30% of sites and one unidentified enchytraeid at a single site. The utility of high-throughput sequencing metabarcoding as a tool for bioassessment of terrestrial arthropod assemblages was confirmed. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
4. Factors influencing individual management preferences for facilitating adaptation to climate change within the National Wildlife Refuge System.
- Author
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Magness, Dawn R., Lovecraft, Amy Lauren, and Morton, John M.
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CLIMATE change research , *WILDLIFE refuges , *WILDLIFE management , *BIOLOGISTS , *INTRODUCED species - Abstract
National Wildlife Refuge System policies reference both historical condition and naturalness, but these concepts may not be valid management goals in a world with rapid climate change. Currently, within the refuge system, managers and biologists can individually decide whether management actions to maintain historical condition (retrospective) or actions to promote and enhance future condition (prospective) are appropriate. In February 2008, we surveyed 203 refuge system managers and biologists (via email) about climate change and management strategies to facilitate adaptation to climate change. Our goal was to explore factors that influence preference for retrospective or prospective strategies. Most managers and biologists (76%) believe that climate change has already influenced their refuge, but land-use change and invasive species were considered more important landscape drivers. We did not find evidence that refuge purpose or inclusion of climate change in planning documents influenced individual preferences about strategies to facilitate adaptation. However, managers and biologists who conceptualize climate change as anthropogenic in origin were more likely to prefer retrospective strategies. Written responses indicate that managers and biologists prefer historical condition, but believe that retrospective strategies will be costly or impossible. Written comments also indicate that managers and biologists prefer strategies that allow species to adapt naturally and without intervention. We conclude that land management agencies need to provide the rationale for how climate change should be conceptualized in the short and long terms. Explicitly addressing conservation values may help to refine agency priorities in a rapidly changing world and to build the consensus necessary to strategically coordinate management across individual units in conservation reserves. © 2012 The Wildlife Society. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
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5. Satellite-Based Assessment of Grassland Conversion and Related Fire Disturbance in the Kenai Peninsula, Alaska.
- Author
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Hess, Katherine A., Cullen, Cheila, Cobian-Iñiguez, Jeanette, Ramthun, Jacob S., Lenske, Victor, Magness, Dawn R., Bolten, John D., Foster, Adrianna C., and Spruce, Joseph
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GRASSLANDS ,BIOCONVERSION ,SPRUCE beetle ,FOREST fires ,INSECT mortality ,GEOSPATIAL data ,DIGITAL elevation models - Abstract
Spruce beetle-induced (Dendroctonus rufipennis (Kirby)) mortality on the Kenai Peninsula has been hypothesized by local ecologists to result in the conversion of forest to grassland and subsequent increased fire danger. This hypothesis stands in contrast to empirical studies in the continental US which suggested that beetle mortality has only a negligible effect on fire danger. In response, we conducted a study using Landsat data and modeling techniques to map land cover change in the Kenai Peninsula and to integrate change maps with other geospatial data to predictively map fire danger for the same region. We collected Landsat imagery to map land cover change at roughly five-year intervals following a severe, mid-1990s beetle infestation to the present. Land cover classification was performed at each time step and used to quantify grassland encroachment patterns over time. The maps of land cover change along with digital elevation models (DEMs), temperature, and historical fire data were used to map and assess wildfire danger across the study area. Results indicate the highest wildfire danger tended to occur in herbaceous and black spruce land cover types, suggesting that the relationship between spruce beetle damage and wildfire danger in costal Alaskan forested ecosystems differs from the relationship between the two in the forests of the coterminous United States. These change detection analyses and fire danger predictions provide the Kenai National Wildlife Refuge (KENWR) ecologists and other forest managers a better understanding of the extent and magnitude of grassland conversion and subsequent change in fire danger following the 1990s spruce beetle outbreak. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
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