Then we have the example of the ducks, ducks make terrible lovers. In fact, ducks routinely exhibit actual forceful mating rituals that would be characteristically referred to as rape, sometimes even gang bangs. Yes it is true that the male of the species forces themselves onto the female in order to reproduce. The males are not choosy, rather opportunistic and forceful. Mother nature is clever though, and the female, although weak in comparison to the male has a little trick up her skirt. The drakes penis is in the shape of a corkscrew. Thus the female duck has evolved a corkscrew pathway towards fertilization, and it is counterclockwise to the drakes. Thus forceful mating will not result in fertilization as the pathways do not line up. If the female duck is willing she will relax her coil and increase the chances for procreation.
So with examples like this in the animal kingdom, why for so long have people relied upon the monogamous penguin, or the pigeon to propagate why humans should practice monogamy? We cannot pick and choose which animals to mould our relationships or bondings after. We need to realize that there is an abundance of variety in the animal kingdom and thus the same within our species. As more studies are published we see penguins have been found to not only be monogamous, but sometimes homosexually monogamous. So even variation exists among the monogamous species. And the moral of the story? Sometimes looking to the animals is not always the best way explain our human sexual desires or relationship groups unless you are planning to use it as an example of variation and unlimited possibilities.