$2$ puffins or only $1$ penguin. In order to get all four animals to the opposite side, what is the minimum number of times the rowboat must cross the sea if at least one penguin or puffin must be in the boat during each crossing?

Two penguins and two puffins are all standing together on the edge of an iceberg and wish to cross to the opposite side to get to the other iceberg. They have a rowboat. Due to the weight capacity of the boat, they can only cross in groups of only