Behavioral Patterns and Nearest Neighbor Distances among Nonbreeding American Avocets

We examined temporal changes in diurnal behavior among nonbreeding American 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., foraging and loafing), nearest neighbor distances (NND), and microhabitat selection (individual water depth). Only foraging and resting, the two most common activities observed, exhibited temporal variation. Foraging varied significantly among all temporal variables [year: P < 0.02; month: P < 0.03; time of day (morning, midday, and afternoon): P < 0.008; 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 foraging avocets during both years, the relationship was significant in 1992 only (P < 0.004). Loafing and multiple scything (a tactile foraging method) were carried out in tight, dense flocks (NND < 1 meter) whereas probing (a visual foraging method) was observed primarily in loose aggregations (NND 1-10 meters). This suggests a strong interaction between maintenance activities and NND. Overall, our study demonstrates that avocets occur in flocks throughout the nonbreeding season, suggesting that flock maintenance is selectively advantageous on the species' wintering grounds.