As They Say, The Bluer the Feet …

There’s only one bird with a funny name and equally funny-looking feet. The blue-footed booby is native to the subtropical regions of the Pacific, where it enjoys coastal temperatures and sunshine. One of this bird’s quirkiest features is its feet. With such an unusual color, the question is often asked: why are the blue-footed booby’s feet so blue — especially these two birds we spotted on @wildlifeandrescue‘s Instagram page? As it turns out, there’s a perfectly logical reason.

Its Diet Causes the Boobies’ Blue Feet

The main diet of a blue-footed booby consists of fish, specifically anchovies and sardines. These fish contain carotenoid pigments responsible for their unique coloration. Therefore, the overall health of the birds is also determined by the vibrancy of their feet. If a bird has bold, bright blue feet, they’ve likely been eating well. The flock often views birds with dull, lackluster feet as weak or unhealthy.

Carotenoids give the birds pigmentation but also serve another purpose. The nutrients contain antioxidants which strengthen the immune systems of blue-footed boobies. However, most of this goes to their feet rather than other parts of their bodies. This evolutionary decision is directly related to the survival of the species.

A Blue Mating Ritual

In a flock of blue-footed boobies, appearance matters. The more vibrant a bird’s feet, the better their chances of finding a mate. Shades of blue determine the male hierarchy of a flock. The bolder and more vibrant a blue-footed booby is, the more females notice him. Bright blue feet mean a healthier bird, which means stronger hatchlings.

According to the Galapagos Conservation Trust, this trait alone determines the winner of a mating dance. During mating season, males parade in front of females to show off their blue feet. During this courtship, male birds’ posture and flaunts are used to get a female’s attention. She chooses based on who has the bluest feet, instinctively knowing this will produce the healthiest offspring. This tactic ensures the survival of the species and explains why carotenoids go to a booby’s feet rather than its immune system. It’s also a testament to how good a bird is at hunting. The more it can consume, the better it is at catching fish, which is highly appealing to females.