DAKOTA NATURAL HERITAGE

AMERICAN WHITE PELICAN

Text by Eileen Dowd Stukel
Photo by Doug Backlund

Every spring and fall, we ask South Dakotans to help us track the movements of whooping cranes as these endangered birds migrate through the state. We invariably receive a call or two where the observer describes a large flock of whooping cranes swimming or floating in the middle of a deep wetland. The reporter is often disappointed to learn that the large white birds with black wingtips are almost certainly not whooping cranes, but rather white pelicans. Although not an endangered species, the American white pelican is impressive and interesting in its own right.

In early April, as whooping cranes wing their way north to their Canadian breeding grounds, white pelicans begin arriving in South Dakota, sometimes before the ice on their large breeding lakes has thawed. This species is colonial in almost all facets of life. Birds arrive unpaired, but soon engage in courtship flights in a group that may number several dozen. Nesting colonies in the Dakotas are typically situated on flat to slightly rolling islands or sandbars of large wetlands. A colony may include thousands of nests, divided into subcolonies of pairs that are closely synchronized in their breeding cycle.

White pelicans begin breeding at 3 years of age. Once paired, the male and female are monogamous for the nesting season. The nest is a shallow depression that matches the shape of the sitting adult. The nest may be lined with vegetation from the nest vicinity, but it is often simply an unlined, uninsulated nest bowl. The female lays the first egg about a day after the nest is completed and the second egg about two days later. A typical clutch has two eggs, with the second laid as insurance in case the first egg does not hatch or the older chick does not survive. The pair defends only the area around its nest.

Pelicans have totipalmate feet, meaning that webbing connects the four toes of each foot. Parents alternate incubation duties every 1-3 days. Adults incubate by covering the eggs with their webbed feet, never leaving the eggs unattended. After about 30 days, the first egg hatches, with the second egg hatching approximately 2 days later, a fateful delay for the majority of the younger chicks.

Chicks are altricial, or helpless, after hatching. The older chick is aggressive to its younger sibling, harassing it during feeding times and physically assaulting it. The younger chick typically does not survive, dying from starvation or falling victim to predators after being forced from the nest by its sibling. By two weeks of age, young are covered with dense down. By 2½ weeks, young can regulate their body temperatures. They begin to leave nests to form crèches or pods, groups of similar-aged chicks. The crèche may serve a thermoregulatory function and likely has an antipredator value, since foraging adults leave young for longer periods as the young mature. If disturbed, older young gather quickly in crèches.

Nesting colonies may be located far from favored foraging areas. North America’s second pelican species, the brown pelican, captures prey by diving into the water. White pelicans employ a completely different method, often benefiting from group foraging. Feeding in shallow water, white pelicans dip their huge bills into the water, collecting both water and small "rough" fish. Water is forced out of the corners of the mouth, leaving the prey fish to be swallowed.

White pelicans often gather in semicircular foraging flocks of a few to a dozen or more birds. The flotilla spreads out and drives prey toward shore with a combination of wing-beating and synchronized bill-dipping. A large foraging flock may subdivide into two groups that drive prey toward each other. In North Dakota, researchers found that the white pelicans in their study area fed primarily on larval tiger salamanders, sticklebacks, black bullheads, minnows, and carp. Researchers visiting nesting colonies have found fish hooks and lures in regurgitated food, indicating that pelicans may capture game fish weakened by anglers.

Prey is swallowed, not carried in the gular pouch. The impressive pouch, which can hold several times more food than can a pelican’s stomach, also serves a thermoregulatory function. When overheated, the bird will flutter the pouch while facing away from the sun. After feeding, adults return to the colony to feed young, with the feeding method changing as the chick matures. Young chicks may eat regurgitated food from the ground or from the end of the lower mandible. As chicks mature, they feed from the top of the pouch, finally reaching down the adult’s throat for food. Parents feed their surviving chick until their early fall departure from the nesting colony.

Fall migrants make their way to wintering grounds. White pelicans that breed east of the Rockies migrate southward and eastward to the coast of the Gulf of Mexico, while western breeders travel southward to California and western Mexico.

This species is adapted to the dynamic water conditions that characterize its breeding grounds, able to shift to new sites if previous nesting colonies have too much or too little water. But the white pelican is not invincible. This species is monitored by the South Dakota Natural Heritage Program because, although nesting colonies often contain many nesting pairs, the white pelican is extremely vulnerable to human disturbance. Early in the nesting season, white pelicans will readily desert their colony if disturbed by humans or mammalian predators, such as coyotes. If disturbed after eggs are laid or young have recently hatched, unguarded eggs and young chicks may fall prey to gulls. Young chicks can withstand only 5 minutes of full sun when left unprotected by their disturbed parents. Young may flee the nest prematurely and fall prey to opportunistic predators. Even motorboats and low flying airplanes can disrupt nesting success.

If you are lucky enough to view one of South Dakota’s white pelican nesting colonies, enjoy this sight from a distance. Do not enter the colony on foot or speed by in a motorboat. My dad, a father of nine, used to say that "children should be seen and not heard." A responsible wildlife watcher is neither seen nor heard. And this spring, if you spot large white birds with black wingtips that turn out to be white pelicans instead of whooping cranes, don’t be disappointed. You have just sighted another member of South Dakota’s rich natural heritage.

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