FEEDING PATTERNS AND AGGRESSIVE-BEHAVIOR IN JUVENILE AND ADULT AMERICAN FLAMINGOS

We studied the feeding and aggressive behavior of adult and juvenile American Flamingos (Phoenicopterus ruber ruber) at a coastal salina in Venezuela. Most birds fed in large flocks in early morning, roosted at mid-day, and resumed feeding in late afternoon-early evening. Flamingos rarely flew, except when disturbed. Adults in our study stepped at the same rates while feeding as did Chilean Flamingos (P. chilensis) feeding in the Chilean and Bolivian Andes. Paired observations of birds within mixed-age flocks revealed that adults stepped more during feeding bouts, but less between bouts, and spent more time overall with their bills in the water filter-feeding, than did juveniles. We calculate that the food-intake rate of juveniles was, at most, 82% that of adults. Both adults and juveniles walk-fed and stamp-fed. Juveniles, but not adults, were twice as likely to be supplanted when stamp-feeding than when walk-feeding. Juveniles were more often involved in aggression, especially as recipients, than were adults. Aggressive encounters significantly affected the amount of time flamingos spent filter feeding.