Monitoring Shorebird Habitat Using Softcopy Photgrammetry: The Case of Western Snowy Plover in the Coal Oil Point Reserve, Santa Barbara, California

[摘要] Abstract The goal of this study was to determine how softcopy digital photogrammetrycan be used to describe and monitor shorebird habitat. I focused on applyingmonitoring methods previously used for beach erosions studies of tourist beaches toshorebird habitat concentrating on the habitat requirements of Western SnowyPlovers. I investigated how the physical habitat of Western Snowy Plovers haschanged over time at Sand Beach, which is part of Coal Oil Point Reserve in SantaBarbara, California, from 1928 to the present day, using width, area, and elevationdata gathered from a series of aerial photographs. For two-dimensional analysis, Iused single georeferenced photographs to measure width at regular intervals and areafor each year a photo was available. Next, for three-dimensional analysis, Iemployed digital elevation models (DEMs) built from stereo photographs to explorewhether the available photos can be used to document changes in the elevation ofSands Beach.The results were mixed. Georeferenced aerial photographs can be used toobtain quality measurements of beach area and width. Orthorectification is notnecessary if photos can be georeferenced with minimal error. The amount of errorpresent in the georeferenced images was indicated by the root mean squared error. Ahigher root mean squared error in the referencing process resulted in lower accuracy.Given the available photos and ground control points, I was unable to build digitalelevation models with high enough quality to compare elevation from one year to thenext. This was more likely due to a need for more ground control points than to theimage scale or image errors.The area of Sands Beach was found to be increasing in area. This was duemainly to the retreat of the vegetation line as the mouth of Devereux Slough shiftedin 1992 rather than an accumulation of sand on the beach.

[发布机构] University of Michigan

[效力级别] Science

[关键词] Natural Resources and Environment;Science;Natural Resources and Environment