Loyal in Love
In the human world, most people practice monogamy and value fidelity towards their partners. This is not the case in the animal kingdom, as it is not conducive for reproduction. Most wild animals mate with several partners of the opposite sex in their lifetime, as this not only increases reproductive rates but also allows them to spread their genes far and wide. However, some animals remain unwaveringly loyal to a single partner. What exactly drives them to develop such long-lasting devotion?
Biologists classify monogamy in nature into two types - social monogamy, where one lives with a single partner of the opposite sex within the same territory during a specific period of time (usually throughout the mating season) while still mating with other partners; and reproductive monogamy, where one mates exclusively with the same partner during a specific period of time without necessarily living together. However, some animals possess characteristics of both types, which means they live and mate with only one partner at a time. Such fidelity is a rarity in the natural world!
Responsible Parents
Long-eared Owls (Asio otus) are surrounded by members of the opposite sex in their day-to-day circles, but genetic analysis reveals a significant overlap between the genes of Long-eared Owls living in the same nest and those of their parents, which is proof that Long-eared Owl couples do not engage in "affairs" outside of their union and live together to care for their offspring. Biologists believe that the cost of raising offspring is high for Long-eared Owls, requiring both parents to share the burden of caring for their offspring to ensure their survival, which is the reason behind their fidelity to one another.
Devoted Lovers
Male Kirk's dik-diks (Madoqua kirkii) are the very picture of devotion when it comes to their partners. Studies have found that they spend over 60% of their lifetime in the company of their partners, especially when their partners are in oestrus, during which they double their protective behaviours, such as extensively marking their territory by leaving scent marks with dung piles, and aggressively chasing away any potential invaders. Female Kirk's dik-diks find it challenging to cheat on their mates under such close surveillance. At the same time, they stay close to their mates to avoid inciting physical conflicts among the males.
Bonded for Life
Fanfin Angler (Caulophryne jordani) inhabits the deep sea at depths of up to 10,000 metres. One can just imagine how incredibly low their chances of encountering a member of the opposite sex are in the vastness of the deep sea! This is why when a male Fanfin Angler comes across a female, he will "latch" onto her, after which their bodies will slowly merge into one, whereupon they become bonded for life! Once they become fused together, the female takes on the responsibility of providing sustenance to the male. This phenomenon is known as "sexual parasitism", which guarantees the female opportunities for fertilisation during the spawning season.
The male has the absolute advantage here, being significantly smaller in size, but considering how unlikely it would be for them to encounter one another in the deep sea, such extreme courtship is perfectly understandable!