Komodo Dragon

Rather than chasing down prey, the Komodo dragon relies on ambush. It waits for hours along game trails, and most hunting attempts fail. When it strikes, its serrated teeth open wounds, and venom glands in the lower jaw release toxins that lower blood pressure, prevent clotting, and can send prey into shock. The saliva also carries about 50 bacterial strains, at least seven of them highly septic, and sources disagree on how much the bacteria and the venom each contribute to the kill. Prey bitten by a dragon typically dies within a few days, sometimes up to four. The dragon can smell carrion from up to 4 km (2.5 mi) away, and some sources say 8 km (5 mi), which helps it find the body. Adults leave about 12 percent of a kill uneaten.

The Komodo dragon’s digestion suits a feast-or-famine lifestyle. An adult can eat up to 80 percent of its body weight in one meal, and up to 88 percent of a carcass. Flexible skull joints and loosely articulated jaws let it swallow chunks of flesh without chewing. It can eat up to 2.5 kg (5.5 lb) of meat in one minute, and in one zoo example a 46 kg (101 lb) dragon ate a 41 kg (90 lb) pig in 20 minutes. Afterward it regurgitates indigestible material as gastric pellets and basks to aid digestion. Dragons have about 60 teeth, and they can survive on a few meals a year. All ages scavenge carcasses. Adults take goats, pigs, horses, deer, water buffalo, and smaller dragons, but carrion makes up a major portion of the diet.

Young Komodo dragons live dangerously because large dragons eat smaller ones. Cannibalism makes up about 10 percent of an adult’s diet. Hatchlings, about 40 cm (16 in) long and weighing about 100 g (3.5 oz), emerge the following April and climb trees to escape the adults below. Sources disagree on how long they stay up there, from about the first 8 months to roughly the first 5 years. Young dragons eat insects, small lizards, snakes, eggs, and birds, and from about age 5 they move to larger prey. At age 5, a dragon weighs about 25 kg (55 lb) and measures about 2 m (6.5 ft). Juveniles come down to feed only after the adults have left the carcass, and females mature at about 5 to 7 years.

Komodo dragons are largely solitary, but a large carcass can draw several together. At a kill, the largest males eat first, followed by smaller males and females, and juveniles come down from the trees to feed after the adults leave. Adults can fight seriously over food, and young dragons perform ritualized appeasement walks around feeding circles. Gatherings at carrion also create courtship opportunities, which matters for a species that spends most of the year apart. During the mating season, normally solitary males leave their home ranges to look for receptive females. In some places males outnumber females by more than three to one, so clashes between evenly matched rivals are frequent. Males patrol up to 2 km (1.2 mi) per day, and Rinca may hold up to 1,500 dragons while Nusa Kode has about 100.

During the mating season, which sources place between May and August, overlapping the driest part of the year, males wrestle rivals upright, trying to throw them to the ground, and the fights often draw blood. The winning male then courts a female by rubbing his chin on her head, scratching her back, and licking her body. Females give off a scent in their feces that males can detect, signaling readiness to mate. The tongue tip is the main scent detector, and some males stay with a female for a few days after mating to keep other males away. About a month after mating, the female digs a nest chamber and lays about 20 to 30 eggs, usually in September. She covers them with earth and leaves, and incubation takes about 7 to 9 months.

Female Komodo dragons can reproduce without a male, a process called parthenogenesis. It was first documented in 2006, when a female at Chester Zoo in the UK produced eggs without mating, and a second UK female did the same within eight months. At London Zoo, four had hatched, and Chester Zoo’s mother, Flora, was awaiting eight babies. All the offspring were male. Females carry ZW sex chromosomes and males carry ZZ, and WW is not viable, so offspring made from the mother’s doubled chromosomes are always male. Nature News described a hypothetical island scenario: a stranded female could wait two or three years, then reproduce on her own and found a population. Without genetic mixing, harmful genes are not masked, so fitness can decline. The article did not say this has happened in the wild.