Survival, movements, and habitat use of female northern pintails in the Playa Lakes Region
Despite other waterfowl species recently being at or near all-time population highs, numbers of breeding northern pintails (Anas acuta), hereafter pintails, have been declining since the late 1970s. Population estimates remain well below the goal of 5.6 million birds established by the North American Waterfowl Management Plan and reached an all-time low of 1.8 million birds in 2002. A number of hypotheses have been proposed to address current population declines including: low nest success, poor breeding propensity, disease (avian cholera [Pasteurella muttocida], avian botulism [Clostridium botulinum] and lead poisoning), low breeding-season survival of adults, habitat loss, and low survival during migration and wintering periods. The Playa Lakes Region (PLR) of northwest Texas provides migrating and wintering habitat for over a million waterfowl each year and is the second most important wintering area for waterfowl of the Central Flyway. Even with relatively high population levels in 2003, numbers of pintails wintering in the PLR also have been declining since the late 1970s. The objectives of my research were to (1) assess variation in body structure of pintails wintering in the PLR, (2) evaluate body condition of migrating and wintering pintails, (3) estimated and identify variables influencing over-winter survival and mortality, (4) assess the daily cycle of movements for female pintails wintering in the PLR, and (5) discern habitats important to wintering pintails in the PLR.