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DETECTABILITY AND OCCUPANCY OF THE COMMON RAVEN IN CLIFF HABITAT OF CENTRAL APPALACHIA AND SOUTHEASTERN KENTUCKYFelch, Joshua Michael 01 January 2018 (has links)
Nearly extirpated from the Central Appalachians, USA by the mid-1900s as a result of human persecution, loss of forests, and absence of large mammal carrion, remnant populations of common ravens (Corvus corax) have recolonized portions of their historical range. One such area of recolonization is southeastern Kentucky where the species is listed as state threatened. Southeastern Kentucky appears to have extensive suitable breeding habitat, but raven records remain relatively rare with sightings and a few nests being confirmed during the past three decades. Because little is known about local ecology or population status of this reclusive corvid in Kentucky, I assessed distribution and occupancy of ravens in available cliff habitat to quantify factors that affect detectability of ravens, identify landscape attributes important to raven breeding locations at multiple scales, and develop a protocol for monitoring occupancy of potential raven breeding habitats in Kentucky. Based on surveys of 23 cliff sites during 2009–2010, I found that ravens are highly detectable (p=0.90 (95% CI = 0.81–0.95)) at known occupied cliff sites, suggesting a survey effort consisting of two visits, each lasting one hour, will enable occupancy to be determined with 95% confidence. Using this and the habitat information associated with occupancy (cliff area and horizontal strata orientation), a monitoring protocol was developed and initiated in 2011 that should be useful to wildlife managers and land stewards interested in long-term monitoring, management, and conservation of common ravens in Kentucky’s cliff habitat.
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Common Raven Density and Greater Sage-Grouse Nesting Success in Southern Wyoming: Potential Conservation and Management ImplicationsDinkins, Jonathan B 01 August 2013 (has links)
My research was focused on greater sage-grouse (Centrocercus urophasianus; hereafter "sage-grouse") nest-site selection, nest success, and hen survival in relation to avian predators. The trade-off between using habitat and avoiding predators is a common decision for prey species including sage-grouse. In Chapter 2, I compared avian predator densities at sage-grouse nest and brood locations to random locations. Sage-grouse were located where densities of small, medium, and large avian predators were 65-68% less than random locations.
The effects of anthropogenic and landscape features on habitat use of sage-grouse hens have not been evaluated relative to avian predator densities. In Chapter 3, I compared anthropogenic and landscape features and avian predator densities among sage-grouse locations (nest, early-brood, late-brood) and random locations. I found sage-grouse hens chose locations with lower avian predator densities compared to random locations, and selected locations farther away from anthropogenic and landscape features.
Depredation of sage-grouse nests can be an influential factor limiting their productivity. Predator removal has been simultaneously proposed and criticized as a potential mitigation measure for low reproductive rates of sage-grouse. In Chapter 4, I hypothesized that sage-grouse nest success would be greater in areas where Wildlife Services lowered common raven (Corvus corax: hereafter "raven") density. I found that Wildlife Services decreased raven density by 61% during 2008-2011 but I did not detect a direct improvement to sage-grouse nest success. However, sage-grouse nest success was 22% when ravens were detected within 550 m of a sage-grouse nest and 41% when no raven was detected within 550 m. In Chapter 5, I assessed interactive effects of corvid densities relative to anthropogenic and landscape features on sage-grouse nest success. I found that sage-grouse nest success was positively correlated with rugged habitat.
Survival of breeding-age birds is the most important demographic parameter driving sage-grouse abundance. In Chapter 6, I evaluated the effect of raptor densities, proximity to anthropogenic and landscape features, and hen behavior on survival of sage-grouse hens. I found that sage-grouse hen survival was negatively correlated with golden eagle (Aquila chrysaetos) density, proximity to anthropogenic and landscape features, and hen parental investment (nesting and brood-rearing).
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