I don’t know how to start this, but I do not want to start from the beginning since I find the beginning of the penguin life most interesting and disturbing.
So, the penguins live in the groups for around eight months until the time for mating comes. The mating season is in the summer, at least for the King Penguin, that I saw in this one documentary. When the season comes they come back to the island they were born to find a mate. That means that they often mate with the sibling or a cousin which causes a lack of genetic diversity.
Once they find a mate, the couples will stay together throughout the season and they practice their own song, or a mating call so they can find each other the next mating season.
In spite of that, less than one third of the penguins stay monogamous.
Once they bond they indulge in a mating ritual after which they have shared responsibilities raising chicks.
Which brings us to the beginning.
After the egg hatches, there is a chance that the parents have abandoned it, and the hatching goes for in a search for the new parent.
There are parents who lost their eggs and they are more than happy to adopt the lone chick, they are so happy that they compete with other parents that want the chick as well, that in many cases the chick itself get trampled to death by the parents who want to adopt it.
I do not know much about penguins.