The kids are too small to survive on their own without a parent though. Look how tiny they are. Assuming the parent is fully adult, those kids aren't even koyukkuris yet. They can't find food or shelter on their own and will probably die the next time it rains.
In addition, from a evolutionary fitness perspective, the kids have a serious disadvantage to the parent. They have to wait however many weeks or months until they can produce offspring successfully. So let's say, for the sake of argument, the kids did somehow survive and grow into adults. They'd still have a 2? 3? week period before they could have offspring.
The adult Reimu, on the other hand, assuming she survives the encounter, can immediately mate and produce more offspring, without having to wait. So even if the Marisa's babies survive, the shithead traits in the Reimu are still being selected for.
Nicehead traits are selected against in nature. Selfishness is rewarded with survival and the ability to reproduce, whereas the kids of the nicehead has no guarantee for survival.
The whole parental abandonment of offspring is a trend you see in the natural world, actually. It occurs mostly among species in which the adults have no defenses against their predators.
If there is no reasonable chance of the adults being able to defeat a predator, it's advantageous for the parents to dump their offspring (butterflies, mosquitos, grouse, kangaroos, opossums) and live to breed another day.
It's only when the parent itself has a reasonable chance to defeat or drive off a predator that it's advantageous to defend the young (scorpions, cattle, deer, bears, big cats, crocodilians, crabs).
Since yukkuri parents generally are helpless against the creatures that predate them, like remilias, flandres, humans, and flocking birds, it's better for them to run and let their children be eaten. Their reproductive strategy of high births and low survival rates of offspring is also geared towards this.
Everything I've read and seen on them suggests that they're one of those species that defends their offspring aggressively due to low birth rate and slow growth rate of calves >_>;
zidana123 said: Are you sure on the elephants for that one? O_O
Everything I've read and seen on them suggests that they're one of those species that defends their offspring aggressively due to low birth rate and slow growth rate of calves >_>;
Yeah elephants are one of the most maternal mammals out there there... Never heard about the drought thing either :O