Contrary to human notions of romance, true lifelong monogamy in the wild is a rarity.
Only about 3–5% of mammals can be considered monogamous, and for most of them, such unions are primarily related to the joint upbringing of offspring rather than absolute fidelity. Such species include the California deer mouse, the Ethiopian wolf, the Eurasian beaver, and the African wild dog, where the dominant pair leads the pack.
The situation is markedly different for birds. Up to 90% of their species practice monogamy: swans, geese, albatrosses, barn owls, and sea eagles form stable, often long-term pairs. However, even among the so-called 'symbols of fidelity,' such as penguins, unions do not always last a lifetime, and cases of partner switching have been documented among parrots.
Humans, according to the evolutionary scale of the University of Cambridge, occupy an intermediate position: we are more monogamous than lions or chimpanzees, but we fall short of the stability of pairs found in species like the California deer mouse.
