Rivas has documented a few cases of cannibalism in anacondas, in which females have regurgitated mates after eating them. It’s unclear if this female ate her mate; Candisani says they couldn’t see her after she pulled the male into the grass. (See “Cannibalism—the Ultimate Taboo—Is Surprisingly Common.”)
The reason is simple: The male is good protein for an expecting mother, especially one who fasts the whole seven months of pregnancy.“A full 30 percent of her bodyweight goes into making babies. Getting an extra seven or eight kilos of meat before you go into that stage isn’t such a bad idea,” he says.
Males average around nine feet and females average 12, although up to 17 feet is common, Rivas says. Candisani estimated the snake he saw at 23 feet long, which would be unusual. (See “Giant Python Meals That Went Bust.”)However, Rivas noted that the area where Candisani captured the photo, not far from Bonito City in the state of Mato Grosso do Sul, is consistently wet.“
In areas with a strong dry season, [anacondas] can hibernate for months under the mud because life is hard,” he says.But in places that are flooded all the time, they probably have a better food supply, and so might grow larger.” (Read how snakes know when to stop squeezing their prey.)No one has reported seeing the snake since Candisani took his incredible picture, but he hopes that she’s still out there—perhaps looking for another male.
Source : http://news.nationalgeographic.com/2017/02/anacondas-sex-death-brazil-mating/