Name:Red-footed Booby
Alias:Sula sula
Outline:Waterfowl
Family:Suliformes Sulidae Sula
length:68-75cm
Weight:1kg
Life:10-20year
IUCN:LC
Red-footed Booby is a black and white or smoky brown booby with three subspecies.
Red-footed Booby is a resident bird and does not migrate long distances. It mainly feeds on fish, especially Spanish mackerel, and also eats squid and crustaceans. Its throat is loose and pouch-like, so it can swallow larger fish and store them for a long time. The distribution area of the red-footed booby is exactly where typhoons frequently blow, and the typhoon season is long. Whenever a typhoon hits, it can no longer go to the sea to find food. During this period, it mainly relies on the food stored in its throat pouch to survive, and sometimes it is forced to stay near houses to avoid the strong wind. After the red-footed booby has worked hard to catch food, it is often suddenly attacked by predatory birds such as frigatebirds and is forced to give up its prey, so it has formed the habit of spitting out the food stored in its throat after being frightened. Because it is not easy to obtain food, it has a strong ability to endure hunger and can go without food for about half a month. After the typhoon, it will fly and circle in the air far away from the land for a long time every day. When flying, it stretches its neck, lifts its feet backward, and bends its head slightly downward, concentrating on the activities of fish schools on the sea surface and waiting for opportunities to hunt. When flying in groups, they line up in a vertical column, sometimes in a slightly "V" shape, soaring along a wave-shaped route. If it finds prey, it will fold its wings to its body from 20 to 30 meters above the sea surface, dive into the water with a swift posture, capture the prey underwater, and then fly back into the air again. At this time, the sea water will splash like flowers because of the flock of birds jumping into the water, forming a magnificent natural scenery.
Red-footed boobies are typical tropical marine birds, with strong flying ability, good at swimming and diving, and powerful walking on land. At night, it has a strong tendency to be attracted to light, so sometimes it is lured to the deck of a ship or the garden of an islander by light. It flies to the sea to forage every morning and returns to its habitat in the evening. It is very regular, so fishermen can not only find the location of the fish school according to its flying direction and the place where it clusters, but also follow its flying route to determine the direction of return when it loses its way at sea, so it is also called the "navigation bird". It is silent when flying at sea and only makes sounds when it nests.
Red-footed boobies breed on the coast and islands. The time varies from region to region, often starting in March and ending in early autumn. They often nest together in groups, on small trees or dense bushes. Sometimes there are several nests on the same tree, less than 60 cm above the ground, and occasionally on rocks. The nest is large but very simple, in the shape of a platform or disk, made of some branches, weeds and seaweed, with a diameter of about 70 cm. The male and female birds build the nest together. The male is mainly responsible for the transportation of materials, while the female is mainly responsible for the construction. Sometimes they also use old nests and make some repairs before laying eggs. Each nest lays one egg, and occasionally two eggs. The eggs are white and the surface is rough, as if coated with a layer of lime. The size of the egg is 62×41 mm. The parents take turns to incubate the eggs. The incubation method is very interesting. Instead of lying on the eggs like ordinary birds, they step on the eggs under their feet and transfer body temperature to the eggs through the vascularized skin on their feet. The incubation period is 42-46 days.
During incubation, the parent bird places its large webbed feet on the eggs, and the weight of its body is mainly supported by the tarsus. When the weather is very hot, the parent bird does not need to incubate the eggs, but instead stands next to the eggs, using its body to block the strong sunlight to maintain a constant temperature. If there is any interference during the incubation period, the parent bird will take off quickly, rush towards the intruder, and spray feces like raindrops. In order to avoid the attack of frigate birds, red-footed boobies have to go to the sea to forage in groups. When returning, they suddenly "brake" during normal flight and return to their nests in an instant to confuse the "robbers" chasing them. After the incubation period, the parents take turns to forage, but they do not feed with caught fish, but regurgitate the chyme in their stomachs as food. The chicks need to be fed by the parents with half-digested food in their stomachs to grow up. After 3 weeks, they can fly to the sea with their parents. After 5 months, they can fly to the deep sea and live independently.
Despite being protected by legislation, red-footed boobies continue to be illegally hunted in the Cocos Islands, with an estimated 2,000-3,000 birds killed each year between 2004 and 2018. Some degree of hunting also occurs in breeding grounds on many other small Pacific islands. However, this does not seem to significantly affect the nesting of the species there. Clearing of nesting trees for fuel wood or land conversion has occurred on many islands throughout the distribution range, reducing the nesting sites available to the species (Carboneras et al., 2018), but this does not seem to have much impact on this widespread species population.
In October 2022, the red-footed booby "appeared" in Shanghai for the first time.
Listed in the "Red List of Threatened Species of the World Conservation Union" (IUCN) 2018 ver 3.1-Least Concern (LC).
Listed in the Chinese Red Book of Endangered Animals: Vulnerable, effective year: 1996.
Listed in the second level of China's "National Key Protected Wildlife List" (February 5, 2021).
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