BEHAVIORAL-PATTERNS AND NEAREST-NEIGHBOR DISTANCES AMONG NONBREEDING AMERICAN AVOCETS

We examined temporal changes in diurnal behavior among nonbreeding Ame rican Avocets (Recurvirostra americana) in South Carolina during 1991 and 1992. We also assessed effects of ambient temperature on foraging, and studied relationships between maintenance activities (e.g., forag ing and loafing), nearest neighbor distances (NND), and microhabitat s election (individual water depth). Only foraging and resting, the two most common activities observed, exhibited temporal variation. Foragin g varied significantly among all temporal variables [year: P < 0.02; m onth: P < 0.03; time of day (morning, midday, and afternoon): P < 0.00 8; and interaction between month and time of day: P < 0.004], whereas loafing differed significantly between years only (P < 0.02). Although rising temperatures were negatively correlated with numbers of foragi ng avocets during both years, the relationship was significant in 1992 only (P < 0.004). Loafing and multiple scything (a tactile foraging m ethod) were carried out in tight, dense flocks (NND < 1 meter) whereas probing (a visual foraging method) was observed primarily in loose ag gregations (NND 1-10 meters). This suggests a strong interaction betwe en maintenance activities and NND. Overall, our study demonstrates tha t avocets occur in flocks throughout the nonbreeding season, suggestin g that flock maintenance is selectively advantageous on the species' w intering grounds.