Page "Hamster" Paragraph 14

Most hamsters are strictly solitary.

If housed together, acute and chronic stress may occur, and they may fight fiercely, sometimes fatally.

Some dwarf hamster species may tolerate conspecifics.

Russian hamsters form close, monogamous bonds with their mates, and if separated, they may become very depressed.

This happens especially in males.

Males will become inactive, eat more, and even show some behavioral changes similar to some types of depression in humans.

This can even cause obesity in the hamster.