White Ibises occur in many types of wetlands including swamps, mangroves, flooded pastures, freshwater marshes, and shallow ponds. They forage most often in wet areas with less than 8 inches of water and sparse, short vegetation, but they also forage on lawns and in parks, especially in southern Florida where they are now accustomed to humans. They nest in colonies in trees and shrubs near fresh, brackish, or salt water. During the nesting season, they forage more frequently in freshwater wetlands because nestlings cannot safely consume large amounts of salt. During the nonbreeding season, they use coastal wetlands more frequently. Back to top
White Ibises probe for insects and crustaceans beneath the surface of wetlands. They insert their bill into soft muddy bottoms and feel for prey. When they feel something, they pinch it like a tweezer, pulling out crayfish, earthworms, marine worms, and crabs. They also stab or pinch fish, frogs, lizards, snails, and newts. Many of their prey are swallowed on the spot, but for really muddy items they carry them away to wash the mud off before eating. They break harder crustaceans with their bills and remove claws from crabs and crayfish before eating them. Back to top
Females choose where to build the nest within the colony. They typically build nests in forks of live or dead trees such as black elderberry, red bay, black mangrove, willow, and cypress. If taller nest sites are unavailable, they often nest in clumps of grasses or sedges. Nest height ranges from 0.5–12 feet above the ground. The location of breeding colonies often changes from year-to-year.
The male gathers sticks for the nest either from the ground, a nearby nest, or a dead tree. He gathers most of the nest material, but the female does gather some sticks on her own. He gives the sticks to the female, which she arranges into a messy platform about 10 inches wide and 2–4 inches tall. Occasionally the male helps place the sticks into the nest or they do it together. It takes about 7 days to build a nest, and they continue to maintain the nest throughout the nesting cycle.
|Egg Description:||Cream to blue-green eggs with brown splotches.|
|Condition at Hatching:||Helpless with closed eyes. Body covered in black and gray down.|
White Ibises are social birds; they forage in groups, fly in groups, and nest in colonies. They walk slowly through wetlands probing for prey in muddy bottoms or picking prey off the surface. In flight they alternate between rapid wingbeats and glides and can travel around 30 miles per hour. Although they are birds of wetlands, they roost and nest in trees. When they reach the nesting colony they free fall into the tree or shrub in a rather ungainly manner. Males gather in large groups at the colony site prior to breeding to attract a female. They perform several displays that involve head shaking, preening, group flights, bathing, and bill popping. During group flights, males spiral up and down near the colony to show off. They also take group baths, preen extensively in front of females, and nibble on twigs with their bills—called bill popping. Once they've wooed a mate, they grab and shake the head of their female, sometimes causing her to bleed. After the somewhat brutal courtship, they continue to bond by greeting each other with sticks, crossing their necks, and preening each other. Males and females form seemingly monogamous pairs, but males often mate with more than one female, a behavior known as extra-pair copulation. Males defend their nest and their female from rival males and predators. If a male feels threatened, he lunges at a rival male and snaps his bill. If a rival gets too close, the territory owner attacks by biting or holding down the rival's wing or head. Both males and females incubate the eggs and care for the nestlings. Parents feed the chicks for 40–60 days after they leave the nest (but before they leave the colony) until they can forage by themselves. Even so, juveniles take a while to learn the finer points of foraging and often keep to the periphery of the group where they can practice. Flying in a flock also takes some practice; juveniles don't master the technique until they are 2 months old. Back to top
White Ibises are common and their populations have grown by 4% per year from 1966–2015, according to the North American Breeding Bird Survey. They now occur in relatively urbanized areas especially in southern Florida where they have become habituated to humans (some are even being hand fed). Partners in Flight estimates the global breeding population at 290,000. The White Ibis rates 12 out of 20 on the Continental Concern Score, which means it is not on the Partners in Flight Watch List. White Ibis like other wading birds rely on wetlands for breeding and foraging, thus changes to wetlands by altering water levels can affect breeding success and survival. Back to top
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