Members of the weasel family, otters are adorable creatures populating fresh and saltwater habitats throughout the world. There are 13 species of otters in total, the vast majority living in rivers, lakes, or wetlands. No matter what species they are, otters generally live in family groups. That makes people believe that they are monogamous. But do otters mate for life?
The table below outlines the different species of otters along with their relationship type formation and approximate gestation period:
|Otter Species||Relationship type||Gestation period|
|Northern River Otter||Polygamous||58 – 62 days|
|Sea Otter||Polygamous||122 – 365 days|
|Giant Otter||Monogamous||68 – 70 days|
|Marine Otter||Monogamous||60 – 65 days|
|Southern River Otter||Polygamous||300 – 365 days|
|Neotropical Otter||Polygamous||57 – 86 days|
|Eurasian Otter||Polygamous||60 – 70 days|
|Hairy-Nosed Otter||Monogamous (possibly)||60 – 70 days|
|Smooth-Coated Otter||Monogamous||61 – 65 days|
|Small-Clawed Otter||Monogamous||60 – 65 days|
|Cape Clawless Otter||Polygamous (possibly)||58 – 63 days|
|Congo Clawless Otter||Polygamous (possibly)||57 – 65 days|
|Spotted Neck Otter||Polygamous||60 – 60 days|
Do Otters Mate For Life?
Yes, some otters mate for life. However, most otter species are polygamous and do not mate for life. Monogamous otters may or may not mate for life. Small-clawed otters mate for life and generally choose not to find another partner if their original partner dies. However, otters in other monogamous species may find a new partner in case of their original partner’s demise.
Polygamous vs. Monogamous Otters
Depending on the species, otters can be polygamous or monogamous.
Most otter species (eight out of 13) are polygamous and have multiple partners throughout their life. Male otters of polygamous species are generally solitary, while the females live in groups with their pups.
For example, in Northern river otters (or North American river otters), males and females only associate during the mating season.
Southern river otters display a similar behavior; family groups consist of females and their young, while males are usually solitary.
Monogamous species choose one partner, usually for life. In these species, the family groups consist of both parents and the pups. Male otters assist the female with the nest building and food procurement, including caring for the pups before and after the weaning period.
Monogamous otter species include giant otters and marine otters – not to be mistaken for sea otters that are a different, polygamous species.
Both otter species found in North America – the Northern river otter and the sea otter – are polygamous.
Sexual Maturity And Reproductive Cycles
North American otter species reach sexual maturity between three and five years of age, on average. A study evaluating the sexual maturity of Northern river otters concluded that male otters are generally sexually mature at about three to four years of age. Female otters also reach reproductive maturity at around the same age.
Similarly, scientists concluded that female sea otters reach sexual maturity between two to five years of age. However, male sea otters have a slower developmen and only become sexually mature at about five to six years.
Other otter species develop at more or less the same rate, young otters reaching reproductive maturity at 3-4 years, on average.
Most otter species have an estrous cycle of 28 days and an actual duration of the estrous of three days, but the reproductive cycles and periods can vary from species to species.
With the exception of sea otters and Southern river otters, most species have a gestation period of about two months. However, some otters can employ the delayed implantation of a fertilized egg, so the young may be born even a year after sexual intercourse despite the short gestation period.
While most people see otters as pacific animals, they generally display violent mating behavior. Males generally approach females indiscriminately until they find a receptive one. Then, the partners begin a vigorous play of swimming and chasing before copulation.
In some species, the male partner bites the female’s nose and upper jaw, often leaving injuries and scars. The behavior is sometimes aggressive enough to kill the female.
Do Otters Pair Bond?
All otter pairs bond for a determined period of time, but only some bond for life.
Polygamous otter pairs only bond for a few days during the mating season. The rest of the time, male and female otters may live in the same habitat, but they will only tolerate each other. Polygamous female otters form social bonds with their pups and create strong family units. Males in these species generally lead solitary lives.
Monogamous otter pairs bond for life. Species like the small-clawed otter share incredibly strong bonds with their partners and may choose not to find another partner if their original partner dies. However, otters in other monogamous species may find a new partner if their original partner dies.
These bonding patterns can help researchers determine the most likely mating behavior of less-known otter species. These species include the hairy-nosed otters, Cape clawless otters, and Congo clawless otters.
While these endangered species can rarely be observed in the wild due to their low numbers, scientists assume that hairy-nosed otters are monogamous – the limited evidence suggests that they live in groups formed by two parents and pups – whereas Cape clawless otters and Congo clawless otters are most likely polygamous since males have solitary lives.
Number of Pups (Litter)
Most otters give birth to one to six pups per litter, with the exception of sea otters and Southern river otters.
These two species have long gestation periods: between four and 12 months and ten and 12 months, respectively. Both species only give birth to one or two pups per litter.
The pups are generally born with fur but are otherwise helpless. Weaning generally begins when the pups are three months old, but the young will remain in their natal range for another three to nine months after weaning.
Otter Reproduction Facts
There are many species of otters, all with their own reproduction peculiarities. Here are a few facts you might like to know:
- Almost all otters give birth on land. Of all otter species, the only one that gives birth in water is the sea otter.
- Some otter pups can be heavy. We talk about sea otters once again. A newborn pup can weigh about five pounds. By comparison, most other otter pups weigh under five ounces at birth.
- Otter parents entice pups with food. About ten days after the pups open their eyes, they start venturing outside the natal dens to take their first swimming lessons. At this stage, females may use food to attract them in water.
- Males swim faster during mating season. When courting, males adopt a face-down swimming posture that enables them to swim faster than normal.
- Some otters can delay implantation. Delayed implantation allows females to keep the fertilized egg in a sort of stand-by and only proceed with the gestation when the time is right.
Do otters kill their mates?
Otters don’t kill their mates on purpose, but the injuries inflicted during mating could kill a female otter.
Do sea otters live alone?
Male sea otters generally live alone, whereas females create family groups with their young.
How long do sea otters stay with their mother?
Sea otters stay with their mothers for about six months until they develop survival skills. However, some pups may stay longer, up to 12 months.
Otters are adorable animals, but not all of them mate for life. In fact, most otter species are polygamous. However, the ones that mate for life may refuse to find a new partner if their original partner dies.
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