Habitat Use of Female Northern Pintails in the Playa Lakes Region of Texas

Playas and other wetlands of the High Plains provide important winter and migration habitats for the continental population of northern pintail (Anas acuta). Factors hypothesized to influence habitat use by pintails in the Playa Lakes Region of Texas (PLR) include wetland type, annual rainfall, and natural and anthropogenic disturbance. We assessed patterns of habitat use for 133 and 164 radio-tagged female pintails 23 October 2002-18 February 2003 and 10 October 2003-18 February 2004, respectively, in the PLR. Birds were continuously monitored for a 24-hour period at least three times a week. We used log-linear models to compare habitat use (playa wetlands, reservoirs, feedlot lakes, irrigation tailwater pits) among months (October-February), daily time periods (predawn, morning, mid-day, and evening), surrounding landuse, (e.g., agricultural fields, Conservation Reserve Program [CRP] grasslands, urban areas, and mixed [two or more habitat types in association with one wetland]), and percent emergent vegetation cover within wetlands (0-25, 25-50, 50-75, 75-100%). Playa wetlands were the predominant habitat used by pintails, accounting for over 98% of observations for both years. During 2002-03, female pintails used playas surrounded by mixed watersheds more than other habitats in October and during evening, and playas surrounded by CRP for the remainder of the winter and other time periods. During 2003-04, playas surrounded by CRP watersheds were used in greater proportion during morning and mid-day time periods during November, January, and February. In 2002-03, playas with greater percent vegetative cover were used in greater proportion during December, January, and February than October and November, and during the morning, mid-day, and evening time periods. During 2003-04, female pintails used playa wetlands with greater vegetative cover during December, January, and February, with greater use of more percent cover occurring throughout all daily time periods. Playas with increasing cover of emergent vegetation were increasingly used possibly due to decreasing water levels, increased food availability, protective microhabitats, and disturbance avoidance in heavily vegetated playas.

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