Survival of Female Northern Pintails Wintering in the Playa Lakes Region of Northwestern Texas

The continental population of northern pintails (Anas acuta; hereafter pintails) has declined since the late 1970s, possibly due to poor breeding propensity, low nest success, and low survival rates in response to habitat loss. Survival estimates are unavailable for several winter and migration areas including the Playa Lakes Region (PLR) of northwestern Texas, USA. We investigated winter survival rates, documented periods of mortality, and identified possible causes of mortality for 159 and 168 radiotagged female pintails during 23 October 2002–18 February 2003 and 10 October 2003–18 February 2004, respectively. We located all radiotagged pintails at least once weekly to verify survival status and usedknown fate modeling in program MARK to test the influence of capture period, female age class, body mass, and capture location on survival rates. Cumulative survival for the 119-day period in 2002–2003 was 0.925 (95% CI 1⁄4 86.0–96.3). During 2003–2004, for a 134-day period, survival estimates declined to 0.694 (95% CI1⁄4 57.1–79.5). The period of highest mortality occurred during the pintail hunting season with 88% of deaths during 2002–2003 and 34% of deaths during 2003–2004 occurring during this period. Age class and capture period did not affect survival rates either year. There was a positive linear correlation between body mass at time of capture and survival rates during winter for 2003– 2004. The lower survival during 2003–2004 was probably due to fewer wetlands being available in the PLR. Our results suggest that habitat conditions and hunting disturbance impact survival of pintails in the PLR of Texas. To maintain or increase wintering pintail survival in the PLR, management should expand wetland availability to wintering waterfowl, enhance food resources, provide refuging areas, and initiate a means for perpetual conservation of playas. (JOURNAL OF WILDLIFE MANAGEMENT 70(3):777–783; 2006)