Morphological Characteristics

The members of Pelecaniformes are considered to be “higher water birds,” as they spend the majority of their time in or near water and feed on many aquatic organisms, including fish, crabs, and frogs.   These birds also have long, narrow, or prominent bills, which provide insight into the food they eat.  Most members of the order have long legs and necks.

As recently as a few years ago, most current members of this order were classified in Ciconiiformes, and Pelecaniformes consisted of not only pelicans, but cormorants, frigatebirds, boobies, and anhingas as well.  After molecular analysis was conducted, the latter four groups were moved into a new order, Suliformes.

• Ardeids (bitterns, egrets, and herons) tend to have either white or grey, brown, or pale blue plumage.  Their display feathers were highly desirable during the late 19^th and early 20^th centuries, as they were used to decorate hats.  Ardeids are slender with long, thin necks that aid in catching prey.  They generally stand perfectly still, sometimes for hours, waiting for a fish or frog to swim nearby.  The bird then shoots its head and neck forward to grab or spear the prey.   Ardeids fly with their necks retracted in an S-shape, and they have long, narrow, spider-like toes.

Yellow-crowned night heron.  Note the retracted neck while flying.

Great blue heron fishing.

• Members of Threskiornithidae have partly naked faces and partially webbed feet.  They fly with their neck outstretched.   The bills of ibises are very narrow and curve downward, while the bills of spoonbills are flat and broad.  Ibises and spoonbills are morphologically different and easily differentiated from each other, but they are genetically similar – hybridization has been documented.

Partially naked faced and curved bill of a white ibis.

Semipalmated feet of a roseate spoonbill.

• Pelicans (Pelecanidae) are the record holders for the longest bill of any bird – up to 50 centimeters long on the Australian pelican!  Their bills are also unique because of their enormous gular pouches, which are used to scoop up gallons of fish.  Similar to Ardeids, pelicans fly with their necks retracted, but unlike Ardeids, they have webbed feet.  Pelicans have relatively short legs compared to other species in the order, short tails, and long, broad wings.

American white pelican with black flight feather tips to reduce wear.

Sources

1. Alderfer, Jonathan.  2006. Complete Birds of North America, pp. 110-124. National Geographic, Washington, D.C.
2. Peterson, Roger Tory.  2010. Peterson Field Guide to Birds of Eastern and Central North America, 6^th Edition, pp. 76-84. Houghton Mifflin Harcourt, Boston and New York.