Pelicans are among the most iconic and easily recognized birds, known for their large bill and majestic presence on water bodies.

One of the most fascinating aspects of pelicans is their occasional color change, particularly the transformation some species undergo, which can result in a distinctive pink hue.

But what causes this change? Let's explore the reasons why pelicans turn pink, the biology behind their color change, and the environmental and behavioral factors involved.

Understanding Pelican Species

Before diving into the specific reasons why pelicans turn pink, it's important to understand that not all pelican species undergo this transformation. Pelicans belong to the family “Pelecanidae”, and there are eight known species globally. Among these, the most well-known for turning pink are the Great White Pelican (Pelecanus onocrotalus) and the Dalmatian Pelican (Pelecanus crispus).

In general, pelicans have pale plumage, often ranging from white to gray, depending on the species. However, during certain periods of their life cycle, especially the breeding season, some pelicans develop a pinkish or rosy tinge. This color change is most pronounced in the Great White Pelican, which can develop bright pink skin and feathers under specific circumstances.

The Role of Diet

One of the primary reasons pelicans turn pink is related to their diet. Like flamingos, pelicans' diet largely influences the color of their plumage. Both birds eat a significant amount of fish and other aquatic creatures rich in carotenoids. Carotenoids are naturally occurring pigments that are responsible for the red, orange, and yellow colors found in various plants and animals. When ingested by pelicans, carotenoids are broken down and deposited into their feathers and skin, resulting in a pinkish hue.

The main source of carotenoids for pelicans comes from the fish they consume, which, in turn, get their carotenoid content from crustaceans, plankton, or algae. In pelicans, this color change is particularly noticeable in the breeding season when their diet intensifies and the carotenoid intake is at its peak. The extra boost of carotenoids helps give them a brighter, more striking appearance, which plays a role in attracting mates.

Hormonal Changes and Breeding Season

Beyond diet, hormonal changes during the breeding season also play a critical role in the pelican's color transformation. As pelicans prepare to breed, their bodies undergo hormonal shifts that trigger changes in their physiology, including the enhancement of pink coloring. The reason behind this is tied to mating displays and courtship rituals.

In many bird species, bright or vibrant coloration serves as a signal of good health and genetic fitness. Pelicans with more intense pink coloring are likely to be seen as more attractive mates, as their coloration may indicate their superior foraging ability and overall vitality. This seasonal color change, therefore, is not just a biological curiosity but a crucial part of the pelican's reproductive strategy.

During the breeding season, pelicans are also known to undergo other physical changes, including the development of bright, vibrant facial skin colors and a raised bump on their bills, known as a "nuptial tubercle," which disappears after the season ends.

Environmental Factors and Health

While diet and hormones are key to pelicans turning pink, environmental conditions can also play a role. Pelicans living in regions with abundant fish rich in carotenoids tend to have brighter pink coloration. In contrast, pelicans in areas where these types of fish are less common might not exhibit the same vibrant colors.

Moreover, the health of a pelican can influence its coloration. Healthy pelicans are more likely to display the pink hues associated with high carotenoid consumption, while stressed, sick, or malnourished pelicans may lose their pink coloring and revert to a duller, more washed-out appearance. This indicates that the pink coloration can serve as a sign of both environmental richness and individual health in pelican populations.

Species-Specific Variations

Though the Great White Pelican and Dalmatian Pelican are most famous for turning pink, not all pelicans undergo this color change. The Brown Pelican (Pelecanus occidentalis), for instance, remains predominantly brown and does not develop the pinkish hue, as it lives in different habitats and feeds on a different variety of prey with less carotenoid content. Other species, like the American White Pelican (Pelecanus erythrorhynchos), may show slight color changes but do not turn as distinctly pink as their European counterparts.

The pink coloration in pelicans is a fascinating example of how diet, biology, and environmental factors interplay to influence animal appearance. Carotenoid-rich diets, hormonal changes during breeding season, and the overall health of the bird contribute to this transformation. Not only does turning pink have aesthetic value, but it plays a crucial role in pelican mating rituals, allowing them to signal their health and vitality to potential mates.

As iconic symbols of wetland and coastal ecosystems, pelicans continue to captivate us with their striking beauty and unique biological traits. The pink pelican stands as a testament to the wonders of nature’s intricate designs, where color plays a vital role in survival and reproduction.