Ibises are a group of long-legged wading birds found in wetlands and plains across the world. There are several different species of ibis that come in a variety of colors. The plumage of ibises enables them to camouflage well in their natural habitats.
Plumage Colors of Common Ibis Species
Here are some of the most common ibis species and the colors they exhibit:
Sacred Ibis
The sacred ibis (Threskiornis aethiopicus) is an all-white ibis with black wingtips. It has a long downcurved bill and red legs and feet. Its white plumage helps it blend into the reedy marshes where it feeds.
Glossy Ibis
The glossy ibis (Plegadis falcinellus) has dark brown plumage that glosses purple and green in sunlight. It has a dark brown face and neck with a bronze-green back. Its wings appear purple-chestnut colored. The underparts are reddish-brown.
Australian White Ibis
As the name suggests, the Australian white ibis (Threskiornis moluccus) has predominantly white plumage. However, its wings have black tips and edges. Adult ibises develop a straw-like color on the neck and head during breeding season.
Scarlet Ibis
One of the most colorful ibis species is the scarlet ibis (Eudocimus ruber). It has vivid scarlet plumage covering its entire body except for its black wingtips. Its bill and legs are red too.
Northern Bald Ibis
The northern bald ibis (Geronticus eremita) has an unfeathered red face and head. Its neck has a ruff of white feathers tipped with black. The rest of its plumage is glossy blue-black with green and coppery sheens.
Purpose of Ibis Plumage Colors
Ibises exhibit a range of plumage colors from white to scarlet to brown. Here are some of the main functions of their coloring:
Camouflage
Species like the glossy ibis have dark plumage that allows them to blend into swampy environments filled with dark-colored vegetation. The white plumage of sacred ibises matches the color of reeds and egrets they live amongst.
Signaling
Bright plumage colors like the scarlet ibis’ red feathers may help in mating displays. The brightly colored bare skin on an ibis’s face and head can also assist in signaling and communication.
Heat Regulation
Light colors like white may serve to reflect heat in hot environments. Darker plumage absorbs more heat from the sun which can help keep the bird warm.
Breeding Indicator
Some ibises develop different feather colors during breeding season. The straw-like neck feathers of Australian white ibises signal they are ready for breeding.
Plumage Differences Between Males and Females
In most ibis species, males and females have identical plumage colors. The sexes can be nearly impossible to distinguish in the field. Here are some small differences between males and females:
- Male sacred ibises tend to develop longer plumes on the rump during breeding season.
- Male glossy ibises may exhibit a slightly glossier sheen to their plumage.
- Female northern bald ibises are typically a bit smaller than males.
Aside from those subtle differences, male and female ibises exhibit the same plumage colors year-round.
Plumage Color Changes Throughout the Year
While their main plumage colors stay the same, some ibis species do undergo changes during breeding season or as juveniles:
Breeding Plumage
- The necks of Australian white ibises turn straw-like brown.
- Sacred ibises grow long decorative plumes on the rump.
- Scarlet ibises become brighter red with more black on the wings.
Juvenile Plumage
- Juvenile scarlet ibises are orange-brown before gaining red plumage.
- Young northern bald ibises have black feathers before they turn white.
- Glossy ibis chicks are covered in gray down before molting.
Diet Affects Ibis Plumage Colors
The main foods an ibis eats can influence the intensity of its plumage colors. Here are some connections between ibis diet and coloration:
Carotenoids
Scarlet ibises get their bright red coloring from carotenoid pigments in the crustaceans and other aquatic life they eat. If their dietary intake of carotenoids declines, so does the vibrancy of their plumage.
Crustaceans
The pinkish-reddish plumage of glossy ibises may result from pigments obtained from eating shrimp, crayfish, and other crustaceans.
Algae
The straw-colored neck feathers of Australian white ibises during breeding season are due to carotenoid pigments from algae. More carotenoid-rich algae can produce darker straw colored feathers.
Conclusion
Ibises exhibit a diverse array of plumage colors and patterns that serve functions like camouflage, heat regulation, and communication. While colors are generally consistent between sexes, some species develop special breeding plumages. Juvenile birds may also be colored differently until they molt into mature adult plumage. Diet can significantly impact the intensity of carotenoid-based colors in ibises like reds and pinks. Overall, ibis plumage allows these tactile wading birds to thrive in the wetland ecosystems they inhabit.