The world is fairly simple, when you're a kid. We quickly and easily identified black and white, for example, “good” and “bad” animals. Herbivores are the good guys, who live together and don't hurt anyone. While predators are the bad guys, that prevent herbivores to live in harmony and sometimes kill them.
Growing up, we learned about the balance of forces in nature, about food chains, evolution and comprehended the basics of biology. And it became clear that predators are not to blame for what they do, they just want to eat. We understood that this is the law, so it should be, this is normal.
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<a href="https://www.moya-planeta.ru/files/holder/4f/ef/4fef5d915e10a45df06768cc158631a3.jpg">image source</a></center>
My world turned upside down when I was 11 years old. It was a story on Discovery Channel about the population of wild deer, that live in the North of Scotland. There was a small piece of land, which was in the sea, and deer loved to graze on it. But at high tide the water is completely blocked the passage back to the mainland and the deer were forced to spend there quite a long time.
It was a small island, mainly consisting of bare rocks without vegetation, but with large populations of nesting birds, think it was seagulls. And that's when the deer felt hungry, but didn't find no grass, they realized that birds are also food. I still remember a snippet of a video as an adult beautiful deer scored baby bird with hooves, and then began to eat him. But that's not all…
# Giraffes suck bones of dead animals
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Let's start with the relatively normal things. Quite often people can see giraffe, who chews the bones of dead animals, especially buffaloes or elephants. Looks a bit creepy, if you consider the fact that usually peacefully giraffe chews the little leaves from the tops of trees.
<center>https://youtu.be/pCy7dY8oREs</center>
However, there is a simple explanation, which justify such behavior. In the bones of the dead animal contains large amounts of calcium and phosphorus, which are necessary for the giraffe to maintain the strength of his own skeleton. This is known as <a href="https://en.wikipedia.org/wiki/Osteophagy">Osteophagy</a>.
Giraffes don't eat the bones, but only chew them, using the saliva to dissolve the nutrients. It is noteworthy that the older the giraffe, the more often he prefers to eat bones.
# Seals eat sharks
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Seals are not herbivores and fish is their main diet, but usually not so huge fish… in 2012, scientists for the first time recorded an attack of a seal on an adult shark. The size of the seal was 2.5 meters, while the shark reached lengths of almost 4 meters… she had no chance.
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<a href="https://www.newscientist.com/article/dn27236-killer-seals-develop-a-taste-for-shark-guts/">source</a></center>
Later another scientist noticed how the seal killed 5 adult sharks and ate their internal organs, rich in nutrients. It is worth noting that usually seals eat shellfish, squid and small fish, but not the predatory inhabitants of the ocean. Scientists are at a loss to answer why this species started to hunt for big fish, when their habitat is full of familiar food.
# Ducks eat other birds
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This case has shocked even experienced biologists. The usual mallards attack the chicks of other species (<a href="https://en.wikipedia.org/wiki/Wagtail">Wagtail</a> and <a href="https://en.wikipedia.org/wiki/Redstart">Redstart</a>) with the purpose of food. The mallard's female caught up with the wagtail, and having seized it with a beak began to drown her, then swallowed a dead bird. After some time, an adult drake found a young redstart, the chick did not have time to fly away. Using the beak drake began to drown this bird too.
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<a href="http://www.bbc.com/news/science-environment-40445379">source</a></center>
The scientists are at a loss to explain this behavior of ducks, because their digestive system is not adapted for the digestion of feathers and bones. Presumably, in this way mallards make up for the deficiency of protein in their diet. Due to the contamination of water bodies decreased the number of shellfish and small fish, which they ate before.
# Parrots hunt on sheep
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Small parrots Kea (Nestor Notabilis) from New Zealand, did not know the taste of meat, before the arrival of Europeans to the Islands. Initially, their powerful beak and claws were only meant for climbing trees, in search of fruits and berries. But after some time the parrots realized that they can use them for others task.
<center>https://youtu.be/N6bYV3Xj-rc</center>
Defenseless sheep are very easy and nutritious prey for the replenishment of protein in the parrot’s diet. The parrot jumps on the back of a sheep and using a sharp beak trying to reach subcutaneous fat. The victim dies from blood loss, after that, the parrots gradually eat corpse.
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<a href="http://nzbirdsonline.org.nz/sites/all/files/1200472IMG_0214anew.JPG">image source</a></center>
The use of embedded devices (claws beak) for the new functions is called preadaptation.
### All these changes in the diet of harmless herbivores associated primarily with changes in their habitats. The balance between the hunters and the prey, existed for millennia, was a broken by humans. The introduction of new species in closed ecosystems, deforestation and the capture of pastures, pollution of habitats. All this makes animals adapt in all available ways. Most likely, we will continue to observe more and more deviations in the behavior of well-studied species.
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*sources: <a href="http://www.tandfonline.com/doi/abs/10.2989/1814232X.2015.1013058#.VRUaOvmsUmc">www.tandfonline.com</a>, <a href="http://www.bbc.com/news/science-environment-40445379">Wild ducks caught on camera snacking on small birds</a>, <a href="http://www.nat-geo.ru/nature/1102451-pochemu-zhiraf-obgladyvaet-kosti-buyvola-video/">National Geographic</a>, <a href="https://news.nationalgeographic.com/2017/07/giraffes-eat-skeletons-bones-spd/">Giraffes Seen Feasting on Skeleton—Here's Why</a>, <a href="https://en.wikipedia.org/wiki/Kea">Nestor notabilis</a> images from Google Search.*
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