The Chinese alligator (Alligator sinensis), also known as the Yangtze alligator or historically the muddy dragon, is a crocodilian endemic to China. It and the American alligator (A. mississippiensis) are the only living species in the genus Alligator of the family Alligatoridae. The Chinese alligator is an opportunistic feeder, meaning that it can prey on a variety of different animals depending on what is available. As an apex predator in its restricted habitat, the Chinese alligator's diet reflects its adaptability and crucial role in the Yangtze River ecosystem.
Physical Characteristics and Habitat
The critically endangered Chinese alligator differs from its American counterpart in subtle ways. It's smaller, the head is more robust and its snout is slightly upturned. The eyelids of the Chinese alligator have a bony plate that is missing in the American alligator. Chinese alligators usually grow to about 5 feet (1.5 meters). The largest Chinese alligator measured in recent times was 7 feet and 1 inch--about half the size of the largest living American alligators. The Chinese alligator is the only member of the eight species in the Alligatoridae family to exist outside of the Americas. The Chinese alligator is almost completely black or dark gray in color as an adult. It has a short and broad snout, which points slightly upwards and narrows at the end. Its head is robust, more so than that of the American alligator, with a bony septum dividing its nostrils. It has 72-76 teeth, of which 13-14 are maxillary, five premaxillary, and 18-19 mandibular. Unlike the American alligator, the Chinese alligator is fully armored, including its belly. It contains up to 17 rows of scales across its body, which are soft on its belly and side and rougher on its back. Its upper eyelids have bony plates on them, a feature usually not present in the American alligator. Its tail is wider than that of the American alligator.
In historical times, the Chinese alligator was found in the extensive lakes and marshlands of the middle-lower Yangtze River region and along the river from Shanghai to Jianling City in the Hubei Province. Chinese alligators are found in slow-moving freshwater rivers and streams, including lakes, ponds and swamps. The habitat of the Chinese alligator is bodies of fresh water, particularly wetlands and ponds, in areas transitioning between subtropical and temperate climates. It lives at the base of mountains, in areas where grass and shrubs are common. Habitat loss has also forced it to live at higher elevations than it prefers, where the weather is colder and the soil is unfit for burrow digging.
Dietary Habits
The Chinese alligator is a carnivore, mostly eating fish and invertebrates, such as crustaceans, insects, mussels, clams, and snails. When possible, it eats rodents, other small mammals, and aquatic birds as well. The Chinese alligator is the apex predator where it lives and is an opportunistic carnivore predator that will eat any animal it can handle. Because the alligator is small, it eats smaller animals such as ducks, rats, and other rodents, fish, snails, aquatic crustaceans, amphibians, and insects. A study of the alligator in 1985 showed that snails were the most common animal in its diet at 63%, with 65% of that being river snails and 35% spiral-shelled snails.
Young waterfowl and rodents will be taken if available. It has dull teeth, which allow it to eat prey with shells more easily. There is some speculation that they may prey on turtles as well.
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Hunting and Feeding Behavior
The Chinese alligator is nocturnal in summer. Chinese alligators do most of their hunting at night. This alligator digs burrows, some of which are extensive, with multiple rooms and even indoor swimming pools. Each year in April, the alligators emerge from their winter burrows and find sunny spots in which to bask. It spends its winters brumating or undergoing the reptile version of hibernation. During the warmer months, it basks in the sun since it’s cold-blooded, but hunts at night, largely to avoid humans, its only predator.
Social Behavior and Communication
Social life begins before hatching, as nest mates communicate egg to egg and with parents who open the egg chamber when synchronized hatching begins. Young vocalize to bring the group together and maintain its cohesion, while adults respond to juvenile distress calls. Chinese alligators advertise their location to other alligators through roars, bellows, and hisses. They also snap their jaws and use their lower jaw to slap the water. During the mating season, males cause vibrations in the water that are attractive to females and that a human can just barely hear.
The Chinese alligator is a vocal species, making many different sounds in multiple situations. When communicating with nearby alligators, it produces sounds such as head slapping, hissing, and whining, which have a low sound pressure level (SPL). To communicate long-distance, it produces bellows, which have a high SPL. Both sexes participate in bellowing choruses during the mating season as adults. Lasting an average of 10 minutes, the alligators remain still for the entirety of the chorus, with both sexes responding equally in rough unison. The main purpose of these bellows is to call out to alligator specimens to collect at a specific pond, where individuals choose mates and engage in copulation. Alligators may also bellow to publicize their size, a behavior which occurs in multiple other vertebrates. Young Chinese alligators often communicate with each other and their parents using vocal signals to "maintain group cohesion". Young also make sounds when in danger, which alert adults to help and caution nearby young of the threat. Embryos produce distinctive sounds inside their eggs, which alert the adult female that the nest is ready to be opened.
Reproduction and Life Cycle
Females mature at about four to five years. Chinese alligators are ready to breed when they’re between five and seven years old. Mating occurs in early summer, with the females building nests about two to three weeks later and laying up to four-dozen eggs; fewer than two-dozen is common. Mating occurs in early summer, with the rate of mating being highest in mid-June. The alligator breeds earlier in the year if temperatures are higher. During the time of mating, males commonly search around ponds to find a mate and both male and female specimens are often aggressive to each other. The species exhibits polygamy, with single males mating with multiple females and/or a single female mating with several males. A study of 50 clutches showed multiple paternity in 60% of them, with up to three males contributing.
Nests are typically built about 2-3 weeks after mating, from July to late August. Constructed by the females, they are composed of rotting plants, such as leaves, and are 40-70 centimetres (16-28 in) high. Females prefer to assemble them in areas that have a thick canopy and are far from human disturbance. Generally laid at night, mating typically produces 20-30 eggs, although according to the International Union for Conservation of Nature (IUCN), clutch size ranges between 10 and 40 eggs. After the eggs are laid, the females sometimes leave the nest, but other times stay to protect the eggs. The eggs are about 6 centimetres (2.4 in) in length, 3.5 centimetres (1.38 in) in diameter, and 45 grams (1.59 oz) in weight, making them smaller than the eggs of any other crocodilian. They are typically incubated for about 70 days. On average, the temperature of incubation is 25-26 °C (77-79 °F), including the day and night. This temperature controls whether a young alligator will be male or female (temperature-dependent sex determination), a feature present in many other reptiles. Hatchlings generally emerge in September. Before they hatch, the baby alligators call from inside their eggs to let their mother know to uncover them. She will then, with great tenderness, carry the hatchlings in her otherwise fearsome mouth to the water. She may even, also with tenderness, crack the eggshell in her mouth if the hatchling is having trouble getting out. The mother alligator not only does this but continues to protect her babies until the winter.
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The alligator grows quickly in its first few years, with its growth rate slowing at age five. According to the National Zoological Park, females reach maturity roughly four to five years after birth, although other sources estimate that they mature at age six to seven. It can live to over 50 years, and has been known to reach age 70 in captivity.
Conservation Status and Threats
The population of Chinese alligators is classified as Critically Endangered on the IUCN’s Red List, which means the animal is basically on the edge of extinction. As of 2021, there is a population of between 100 and 150 Chinese alligators left in the wild. The modern range of the Chinese alligator is extremely restricted. Historically, the alligator was widely distributed in the Yangtze river system.
One of the sadder facts of Chinese alligator life is that their only real predator is the human. Humans used to eat the Chinese alligator and may still do so illegally. People also not only hunt them but destroy their habitat through the building of dams and rice paddies. The alligator was even accidentally killed by a poison meant to kill snails. Now, it is legally protected, and killing and capturing a wild Chinese alligator is forbidden. The development of rice paddies caused habitat loss for the Chinese alligator.
The population of the Chinese alligator began to decline in 5000 BC, when human civilization started to grow in China, after having been very abundant in the lower Yangtze area. This area was one of the first places in the world to farm rice, causing much of the alligator's habitat to be destroyed in favor of rice farms. In the 1700s, much of the Chinese alligator's habitat was replaced with farming fields after a large number of people had moved into the area. By the 20th century, its range was reduced to a few small areas around the Yangtze. In the 1950s, the alligator was in three distinct areas: the southern area of the Yangtze (Chang Jiang) from Pengze to the western shore of Lake Tai (Tai Hu), the mountainous regions of southern Anhui, and the provinces of Jiangsu and Zhejiang, primarily in lakes, streams, and marshes.
Chinese alligators are an extremely rare species now found only in a small area of protected reserve along the lower Yangtze River in the Anhui province of China. They were once widely distributed in eastern China throughout the entire Yangtze watershed. These mysterious and little known crocodilians spend much of their time in underground burrows or in water and do most of their hunting at night. They hibernate from early fall until late spring in burrows that they dig into the banks of rivers or wetlands.
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The eggs and hatchlings of Chinese alligators are vulnerable to predation by other alligators, fish, and birds. Adults are threatened only by humans but this threat is significant. People have displaced Chinese alligators from most of their historic range. Encounters between people and alligators usually end badly for the alligators. Despite their protected status, local farmers have been known to kill them out of fear or frustration. Chinese alligators will prey on domestic ducks given the chance, and sometimes dig burrows into the banks of irrigation channels, causing them to collapse.
Conservation Efforts
However, they are being successfully bred in such places as the St. Augustine Alligator Farm and the Bronx Zoo. These zoos and other organizations are helping to restore the wild population of these alligators. As of 2016, at least 20,000 Chinese alligators are living in captivity due to captive-breeding programs, the first initiated in the 1970s. Captive-born Chinese alligators have been reintroduced into their native range, boosting the wild population. Six specimens were released from captivity in 2007, followed by six more in June 2015. As of June 2016, the largest group of Chinese alligators to have been released in the wild was when 18 specimens were reintroduced to Langxi County, part of the species' native habitat, on May 22, 2016. These releases have proven successful, with individuals adapting well to a life in the wild and breeding. A year after the 2007 release, 16 young alligators were found living in the wild. 60 alligator eggs were observed in 2016, distributed in three nests at a wetland park.
The two largest breeding centers for the Chinese alligator are in, or near, the areas where Chinese alligators are still found in the wild. The Anhui Research Center for Chinese Alligator Reproduction (ARCCAR) is the largest of them, housing roughly 15,000 Chinese alligators as of 2016. The center is 5 kilometres (3.1 mi) from the city of Xuancheng, where it makes use of a series of ponds in a small valley. Founded in 1979, the ARCCAR was stocked with 212 alligators collected from the wild over the first decade after its establishment, and received alligator eggs collected by the area's residents and the ARCCAR's own staff from the nests of wild alligators as well. In 1988, the first eggs by human-bred alligators were laid. In 2003, the ARCCAR received a donation of $1.2 million from the State Forestry and Grassland Administration of China (SFGA) and $740,000 from the government of Anhui. This allowed the organization to create two new breeding areas to hold the alligators, 1.6 hectares (4.0 acres) each, as well as heighten the existing fence.
The Chinese alligator is also kept and bred at many zoos and aquariums in North America and Europe. Some individuals bred there have been returned to China for reintroduction to the wild. The first time the alligators were ever transported internationally is believed to have been when several were taken from China to the United States in the 1950s. Among the North American zoos and aquariums keeping this species are the Bronx Zoo, Cincinnati Zoo, Great Plains Zoo, Sedgwick County Zoo, Philadelphia Zoo, San Diego Zoo, Santa Barbara Zoo, Smithsonian National Zoological Park, and St.