Cannibalism helps rattlesnakes recover after birth

Researchers from Mexico, the United States and Spain have recently obtained the first quantitative description of the cannibalistic behavior of Crotalus polystictus after studying 190 reptile individuals. . Research shows that these animals consume an average of about 11% of the mass of postpartum life forms (especially dead eggs and young offspring) to restore energy to the next reproductive cycle.

Lack of information about the cannibalistic behavior of Crotalus polystictus, which led scientists to conduct research in 2004, they continued this study for 3 years in central Mexico where snakes were Bell tail is endemic. They studied 'cannibalistic behavior' in 190 females hatching 239 eggs. They also confirmed that this phenomenon can be justified by 'helping the mother snake recover and regain strength'.

Estrella Mociño and Kirk Setsor, the main authors of the study and researchers at the University of Granada along with Juan Manuel Pleguezuelos, said: 'The cannibal rattlesnake can restore energy. lost for the reproductive process without having to hunt, which is a dangerous act that requires time and energy. '

The study, published in the latest issue of Animal Behavior, shows that the cannibalistic behavior in rattlesnakes is an evolutionary result of their predatory behavior due to the prey of rattlesnakes often dying before being caught. eat meat. Mociño said: 'Vipe snakes generally eat rotten flesh, so it is not uncommon for them to eat eggs that cannot grow in its nest after losing a lot of energy. quantity for reproduction '.

According to the team, this behavior may be explained by four biological factors: birth date (females laying eggs at the end of July tend to eat more cannibals because they have less time to find food. eat and prepare for the next spawning), the rate of young offspring in an egg nest, the level of investment of the mother snake (the more eggs there are, the higher the number of undeveloped eggs, the higher the number of eggs This will later be taken by the mother snake as food), and finally the pressure of being caught ( researchers locked the snakes on average for about 21 days).

Crotalus polystictus rattles in Mexico. ( Photo: Estrella Mociño / SINC)

Of all the females studied, 68% of the mothers ate a part or all of the dead babies, 83% of them ate all and waited a while to do that (about 16 hours) , while some feed immediately after spawning. The remaining 40% 'no cannibalistic behavior' . According to scientists, the cannibalistic behavior 'is not an unusual behavior', and it is not 'offspring attack' because it is not the same as 'those who kill babies'. because the young are dead. It simply restores part of what the mother snake has spent on reproduction, and to prepare for the next birth.

Snakes can distinguish alive or dead cubs

Scientists have shown that there is a very low risk of a snake eating healthy baby snakes, although they look very similar to those who died when they got out of the membrane for 2 hours . During the study there was only one snake mother who ate the live snake.

Mociño and Setser said: 'Mother snakes do not play the same role as mammals or birds, but research shows that they also exhibit evolutionary behaviors, helping children and young children to reproduce and develop. good'.

Crotalus polystictus rattles are classified as 'endangered animals' on the list of protected native wildlife species in Mexico. Limited living environment, urban expansion and agricultural development have become a major threat to snakes.

So far, scientists have identified more than 2,000 individuals of this snake with an average length of 50 to 90 cm, and they have different survival strategies similar to other rattlesnakes in the north. Mexico and the United States.

This reptile has a very fast reproductive rate, which suggests it also undergoes a relatively high mortality rate due to external causes. The results of this study not only offer scientific knowledge about cannibalism in an evolutionary perspective but also 'make people less aggressive towards these snakes'.

Refer:
Mocinodeloya et al.Cannibalism of nonviable offspring by postparturient Mexican lance-headed rattlesnakes, Crotalus polystictus.Animal Behavior, 2009;77 (1): 145 DOI: 10.1016 / j.anbehav.2008.09.020