Flow Alteration of the Lower Rio Grande and White-Winged Dove Range Expansion and Monitoring Techniques
Small, Michael Fielden
Beginning with mechanized farming practices in the 1920s and escalating in the 1950s, native biotic communities have been systematically converted for agricultural land practices and municipal development. Subsequent water demands in the region have increased, particularly for irrigation. Water withdraw ls and construction of Falcon Lake Dam in the 1950s to meet these increased water demands have greatly altered the natural flow regime of this stretch of the Rio Grande. Among the multiple species affected by habitat change, colonial breeding eastern White-winged Doves (Zenaida asiatica asiatica) lost critical riparian habitat. Coinciding with these changes in land-use practice and the destruction of native riparian habitat, has been a change in distribution of eastern White-winged Doves. Eastern White-winged Doves historically reached the northern extent of their breeding range in the LRGV, but have been expanding northward in Texas into urban habitats in concert with the phenology of land-use change in the region. Currently in Texas more breeding White-winged Doves occur north of the LRGV than within it. I evaluated changes in flow of the lower Rio Grande and its effect on habitat loss in the LRGV. I then monitored a recently established population of White-winged Doves in Mason, Texas (Mason County). I evaluated techniques used for monitoring White-winged Doves to determine the most effective method(s) and improved the efficiency of these techniques. Among monitoring techniques evaluated was the use of subcutaneously implanted radio-transmitters, mark-recapture population monitoring, and distance sampling. Currently, distance sampling of White-winged Dove populations is being integrated into a state-wide monitoring program by the Texas Parks and Wildlife Department (TPWD). This technique seems to be an effective and robust method for monitoring White-winged Doves on an ecoregion level in Texas. I evaluated distance sampling methodologies and have elucidated methods for refining the efficiency of the technique. My results will allow the TPWD to maximize resources and more efficiently monitor urban White-winged Doves.
white-winged doves, habitats, riparian areas, environmental monitoring, Lower Rio Grande Valley
Small, M.F. (2007). Flow alteration of the lower Rio Grande and white-winged dove range expansion and monitoring techniques (Unpublished dissertation). Texas State University-San Marcos, San Marcos, Texas.