Yellow-Billed Cuckoo (Coccyzus americanus occidentalis) Habitat Identification Using GPS Surveys and GIS Analysis

Author: Michael R. Kunzmann
Organization: USGS Sonoran Desert Field Station/University of Arizona

125 Biological Sciences East
Tucson, AZ 85721
USA

Phone: (520) 621-7282
Fax: 520) 670-5001
mrsk@sherpa.srnr.arizona.edu

The yellow-billed cuckoo (Coccyzus americanus occidentalis), a widely distributed inhabitant of the interior southwestern cottonwood-willow riparian forest and the mixed broadleaf riparian forest types (Brown, 1982), has become increasingly scarce in the United States. Western yellow-billed cuckoos have been petitioned for possible listing under the Endangered Species Act (1973, as amended). Habitat fragmentation, degradation of riparian woodlands, and the use of pesticides are possible causes of cuckoo decline in the United States (Hughes, J.M., 1999). Unfortunately, habitat factors important to cuckoos have not been convincingly defined (Magill, 1999:2). Dense broadleaf gallery riparian forests with abundant shrub understory are presumed to form an ideal habitat in Arizona. Yet cuckoos are found resident in pecan orchards and other stands that appear to be less than ideal. To delineate potential yellow-billed cuckoo habitat, cost-effective field data collection strategies were utilized, and GIS and modeling efforts were refined to include higher resolution spatial data and a wider array of secondary database attributes required to succinctly define habitat requirements.

Geolink was critical in illustrating the shape and size of yellow-billed cuckoo habitat patches (polygons) in the field. Examination of the vegetation data collected indicates that the field methodologies are sensitive enough to delineate differences in riparian vegetation communities that change as a function of the perpendicular distance from the primary stream course.