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COPYRIGHT 2005 Wilson Ornithological Society
Over the last 40 years, the distribution of White-winged Doves (Zenaida asiatica) has undergone substantial change (Schwertner et al. 2002). Until the mid-1970s, the breeding range in Texas was limited mainly to four counties (Cameron, Starr, Hidalgo, and Willacy) in the lower Rio Grande Valley (LRGV) at the extreme southern tip of the state (Cottam and Trefethen 1968, George et al. 1994). Since then, White-winged Doves have been expanding their range northward; the species has been recorded in Canada (Rogers 1998), with breeding documented as far north as Kansas (Moore 2001). The majority of breeding individuals in the United States, both currently and historically, resides in Texas (George et al. 1994).
White-winged Dove populations have increased substantially over the past 20 years, but only 16% of the Texas population now occurs in the LRGV (G. L. Waggerman pets. comm.). Large breeding populations of Whitewinged Doves have become established in central Texas, with numerous smaller, satellite populations occurring throughout the state. Concurrent with the northward range expansion, White-winged Dove populations are now concentrated in urban areas (West et al. 1993). This represents a dramatic shift in habitat use away from thorn scrub and riparian woodlands of the Tamualipan biotic province (Blair 1950) that characterizes the LRGV (West et al. 1993, Schwertner et al. 2002).
Loss of native habitat and extensive agricultural and industrial development in the LRGV have influenced the distribution of White-winged Doves in Texas (Hayslette et al. 1996). From 1900 to 1950, about 95% of the historic, native breeding habitat was converted for human uses, resulting in significant loss of old-growth woodlands and water diversions from the Rio Grande and Arroyo Colorado (Kiel and Harris 1956, Cottam and Trefethen 1968). In addition, severe freezes occurring in 1951, 1962, 1983, and 1989 decimated citrus groves that White-winged Doves had used increasingly as nesting sites, most likely in response to loss of native habitat (Cottam and Trefethen 1968, George et al. 1994).
A substantial proportion of White-winged Doves concentrating in urban areas north of the LRGV are non-migratory (George 1991, West et al. 1993, Hayslette and Hayslette 1999). Anecdotal evidence suggests that an extended breeding season by non-migratory doves could lead to increased recruitment, with individuals producing clutches before and after the traditional nesting period (Hayslette and Hayslette 1999).
The objective of our study was to document habitat use and productivity of White-winged Doves breeding in a recently colonized urban environment. To track doves, we used subcutaneously implanted radio transmitters. This is the first radiotelemetry-based study of Whitewinged Dove breeding ecology in a metropolitan area.
METHODS
We conducted our study in Waco, Texas (McLennan County), because of its northern location and relatively recent colonization by White-winged Doves; dove densities are high and the human population (202,983; U.S. Census Bureau 2000) provides potential sources of food, water, and habitat. Whitewinged Doves were first recorded in Waco on the Audubon Christmas Bird Count in 1990, and they were first observed breeding there...
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