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From fishermen to family members: What is unique about the reproductive behavior of Eurasian otters?
The Eurasian otter (Lutra lutra), also known as the European otter or Old World otter, is a semiaquatic mammal found in the waters of Eurasia and North Africa. This otter is known for its graceful size and intense fishing abilities, but its reproductive behavior is also particularly unique.
"Although Eurasian otters are known for their non-seasonal reproduction, the flexibility of their reproductive behavior gives us high hopes for the survival of their offspring."
Unlike many other species, Eurasian otters are not bound by seasonality, and males and females can breed at any time of the year. This flexibility in the breeding period depends mainly on the otter's physiological condition. Female otters generally reach sexual maturity between 18 and 24 months of age and usually give birth at around 2.5 years of age. This reproductive strategy enables them to maximize the use of available resources under suitable environments and conditions, thereby increasing the survival rate of offspring.
The gestation period is usually 60 to 64 days, and the female otter gives birth to 1 to 4 pups per litter. When a baby otter is born, it weighs only about 10% of its mother's body weight. For the first 13 months of life, they are completely dependent on their mother's care. Although male otters do not directly participate in raising young otters, female otters usually live within the male otter's territory. This living arrangement may help improve the survival chances of young otters.
Eurasian otters are extremely competitive in their territories, and otters use their feces (called "otter dung") to mark their territories, not only as a means of preventing intrusion by other otters of the same species, but also as a way of maintaining ecological balance. Typically, an otter's territory is 1 to 40 kilometers long, with an average of about 18 kilometers, depending on the abundance of food in the area. Although this creature is primarily solitary in habit, its territory may overlap with that of an otter of the opposite sex during the breeding season, providing an opportunity for reproduction.
"The process of territorial marking and selective mating reflects the wisdom and adaptability of organisms in evolution."
When food sources are sufficient, Eurasian otters live in a wide range of environments, from clear freshwater lakes and rivers to coastal saltwater areas. After obtaining the food they need, they will choose an environment that is suitable for living. . Their diet mainly consists of fish, and when the environment is cold, they will also prey on amphibians, insects and small mammals. This eating habit not only meets their ecological needs, but also enables them to maintain a high survival rate during the breeding season each year.
While ecosystem health plays an important role in the reproductive behavior of Eurasian otters, they are still threatened by environmental pollution and habitat destruction. In the second half of the 20th century, these otters' populations declined significantly due to environmental pollutants, however, with the promotion of conservation efforts, the Eurasian otter population has gradually recovered in many areas.
"In the UK, for example, the number of locations where the Eurasian otter is seen increased by 55% between 1994 and 2002."
This recovery trend is by no means accidental. First, Europe has banned many harmful pesticides since 1979, which has improved water quality and gradually increased food sources. At the same time, legal protections for the Eurasian otter are being implemented in many countries to ensure the survival of these precious creatures.
The reproductive behavior of Eurasian otters is unique in that they can flexibly adjust their mating and reproduction plans according to changes in the local environment. This not only shows the resilience of these animals in nature, but also reminds us how important it is to protect their ecological environment.
So how can we further protect and understand these fish-catching specialists and their unique reproductive behaviours in a changing world?
