this time, males must find females. Typically, female snakes lay down a trail of pheromones for the males to follow, but how the males of this species track a female's scent is still unclear. Another possibility is that the female releases an airborne stimulant. This theory is supported by the observation of females that remain motionless, while many males move towards them from all directions. Male anacondas also frequently flick their tongues to sense chemicals that signal the presence of a female. Many males can often find the same female. This results in odd clusters referred to as "breeding balls", in which up to 12 males wrap around the same female and attempt to copulate. The groups can stay in this position for two to four weeks. This ball acts as a slow-motion wrestling match between the males, each one fighting for the opportunity to mate with the female. During mating, males make use of their spurs to arouse the female. They aggressively press their cloacal regions hard against the female body, while continuously scratching her with their spurs. This can produce a scratching sound. Mating approaches its climax when the stimulus of the males' spurs induces the female snake to raise her cloacal region, allowing the cloacae of the two snakes to move together. The male then coils his tail, surrounding the female, and they copulate. The strongest and largest male is often the victor. However, females are physically much larger and stronger and may decide to choose from among the males. Courtship and mating occur almost exclusively in water. Mating is followed by a gestation period of six to seven months. The species is ovoviviparous, with females giving birth to live young. Litters usually consist of 20 to 40 offspring, although as many as 100 may be produced. After giving birth, females may lose up to half their weight. Neonates are around long and receive no parental care. Because of their small size, they often fall prey to other animals. Should they survive, they grow rapidly until they reach sexual maturity in their first few years, after which they continue to grow at a slower pace. However, when no male anacondas are available to provide offspring, facultative parthenogenesis is possible. In August 2014, West Midlands Safari Park announced that on 12 August 2014 a female green anaconda, which was being kept with another female anaconda, through parthenogenesis had