USE OF HABITATS BY FEMALE NORTHERN PINTAILS WINTERING IN SOUTHWESTERNLOUISIANA

The breeding population of northern pintails (Anas acuta) in 1996 was 39% below the long-term average. Because winter habitat quality may in fluence subsequent breeding population size in pintails, identificatio n of habitats used by wintering pintails and factors influencing use o f habitats may be important for managing for population increase. We e xamined variation in diel use of habitats by radiotagged female pintai ls (n = 272) in southwestern Louisiana in relation to age (imm and ad) , winter (1991-92 and 1992-93), and time period within winters (pre-hu nting season, first hunting season, time between split hunting seasons , second hunting season, and post-hunting season). Diurnal use of refu ges was significantly greater during hunting seasons than during immed iately preceding or succeeding nonhunting seasons. Consequently, we re ject Tamisier's (1976) hypothesis that high diurnal use of refuges by pintails in southwestern Louisiana occurs independent of hunting. Noct urnal use of refuges was low (<14%) during all time periods, and decli ned later in winters. Time-period differences in diurnal and nocturnal use of habitats (large permanent pools, marsh, rice, fallow [idle], a nd other agriculture [primarily soybeans]) were not consistent between winters. Diel use of refuges or habitats did not differ in relation t o female age. Females used fallow and rice agriculture extensively par ticularly at night, and these habitats collectively accounted for 68-9 3% of nocturnal use. Differential use of habitats between winters was related to annual differences in relative abundances of rice and fallo w agriculture. Proximity of refuges to agricultural areas should be an important management consideration for wintering pintails and other w aterfowl.