Occupancy, Abundance, and Landscape Connectivity Analyses of Ring-necked Pheasant in Ohio
Grant Ravary
Advisor: William Peterman
Ring-necked Pheasants (Phasianus colchicus, herein referred to as pheasant) are an introduced game bird that occupy a contemporary niche in Ohio’s agricultural ecosystems, serving as an analogue for the native prairie Galliformes. After their introduction in the 1800’s pheasants reached a peak density in the 1930’s and then began a steady decline. This decline is attributable to the advent of commercial farming and crop subsidies introduced by Roosevelt’s New Deal (1933). These subsidies led to drastic land use change in rural Ohio, replacing grassland and fallow fields with large commercial farms. Like the rest of North America, loss of nesting and winter habitat to commercial agriculture has led to the decline of pheasants in Ohio. This loss of habitat has also led to fragmentation and reduced habitat connectivity between suitable patches. Our current understanding of pheasants’ response to land cover lacks the context of scale and habitat connectivity. These concepts are important for conservation as changes in arrangement and surrounding cover type may render some habitat unusable despite being the preferred cover type. My objectives were to find suitable patches, connections between them, and areas that would improve connectivity. To better inform the conservation of pheasant, I investigated pheasants’ response to cover type and its scale of effect along with habitat connectivity. Using a novel multiscale framework, I analyzed landscape suitability by modeling the influence of cover types on pheasant occupancy and density. To quantify habitat connectivity, I used combination of circuit theory and graph theory to find areas of high importance for connectivity. Conservation Reserve Programs and grassland were both positively related to pheasant occupancy and density at a relatively fine scale, and developed areas and forests had a large negative impact at a broad scale. Additionally, the majority of the state has a low degree of habitat connectivity for pheasant. There are only a few connected clusters of habitat across the state, each with varied degrees of connectivity. By using the outputs from the connectivity and suitability analysis we can better understand what cover types need conservation for the persistence and spread of pheasants across the state of Ohio. This project will help the ODNR locate those areas in need of conservation and restoration in a cost-effective manner to help recover pheasant populations.