Survival, habitat use, and movements of female mallards wintering in the playa lakes region

The objectives of this study were to determine survival rates, habitat use, and monitor movements of female mallards in the Playa Lakes Region (PLR) of the Southern High Plains. In addition, the effects of body condition (body weight/wing length), age, and year upon the survival and habitat use were evaluated. The survival rate of 153 radio-tagged female mallards in the Playa Lakes Region during the winters of 1986-87, 1987-88, and 1988-89 was 77.7%. Log-rank comparisons did not detect any age or annual differences in survival. In some cases, however, at specific times (31 December, 31 January, and 1 March) within the survival distributions of 1986-87, and 1987-88, age differences were found. Survival was lowest in 1987-88 (68.7%) when emergent-vegetated playas were least available. Juveniles experienced the most variable survival between years. Survival rates were highest for individuals in high condition (> median). Almost 93% of the 2 6 recorded mortalities occurred within the low (< median) condition class. Mortality from hunting was minimal; one female died from hunting during each winter. Natural factors accounted for the balance of the mortality. The minimal losses due to hunting indicate that the PLR is unique relative to other areas of the country (e.g., lower Mississippi River Valley) in terms of hunting pressure on mallards. In light of this, maintenance of the High Plains Mallard Management Unit seems justified.

Feedlot sites were most preferred by female mallards. Entrenched draws were also preferred while emergent-vegetated playas were generally used in proportion to their availability. Tailwater pits were used least relative to the other habitat types. Range playas were avoided except during 1988-89. No differences in habitat use were attributed to age. Seasonal differences occurred with tailwater pits, and feedlot sites being used more during late winter relative to the other habitat types examined. Mallards in highest condition used tailwater pits and feedyard sites most while birds in lower condition used emergent-vegetated playas most. As playa lakes froze over during severe weather, mallards generally moved south of Lubbock into more saline playas and riparian draws where open water was available. Overall, female mallards displayed a strong fidelity to the area they were originally captured. Management practices should emphasize increasing water availability in entrenched draws and utilize feedlot lakes and draws as refuge-type habitat. Management of water levels of 7-10 ha, emergent-vegetated playas should also be stressed. Waterfowl managers should pursue landowner implementation of conservation easements of saline draws and playas in the southern PLR.