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 used-known 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 = 86.0–96.3). During 2003–2004, for a 134-day period, survival estimates decli...