Hippos are massive, powerful animals that spend much of their lives in water, often appearing docile as they float in rivers and lakes. This perception can lead to questions about their behavior, especially concerning their young. The reality of hippo life is more complex and can involve surprising interactions within their social groups and with their environment.
Infanticide Among Hippos
Infanticide, the killing of young by an adult of the same species, occurs in hippos, primarily by dominant adult males. While not common, this behavior has been observed. Males may eliminate calves not their offspring as a reproductive strategy, aiming to bring females into estrus sooner for mating. This also reduces future competition for dominance, particularly from young male calves.
Infanticide can be triggered by specific circumstances within a hippo pod. It is more likely when water resources are scarce, leading to overcrowding, or during territorial disputes and shifts in male dominance. When a new dominant male takes over, he may kill existing newborns. While rare, such incidents highlight the intense dynamics within hippo social structures.
Maternal Care and Calf Rearing
Despite male aggression, female hippos exhibit strong protective instincts and dedicated maternal care. A mother hippo forms a close bond with her offspring, which weighs between 25 and 50 kilograms at birth. She typically isolates herself from the main pod before giving birth, often in the water, remaining separate for 10 to 14 days to establish this crucial bond.
During this isolation, the calf learns essential survival skills, including how to suckle underwater. The mother constantly watches over her young, providing a safe “raft” for the calf to rest on her back. She aggressively defends her calf from threats, including predators. This vigilance continues as the calf grows, staying close to its mother for several years until maturity.
Other Perils to Young Hippos
Beyond infanticide, young hippos face numerous environmental dangers. Nile crocodiles are significant predators, often preying on calves when mothers are not vigilant or calves stray too far. Lions and hyenas also pose threats, particularly on land. While adult hippos are largely safe due to their size and defense, calves remain vulnerable.
Accidental deaths are another concern for young hippos. Calves can be inadvertently crushed or trampled by adults, especially in densely populated areas or during pod disputes. Getting caught in territorial fights between adult males can also result in injury or death. Environmental factors like drought exacerbate these risks, forcing hippos into smaller, crowded water sources, increasing stress and competition.
Human activities also contribute to challenges faced by young hippos. Habitat loss due to expanding agriculture and urban development reduces their available living spaces. Poaching for meat and ivory, along with human-wildlife conflict from crop damage, can lead to retaliatory killings that impact hippo populations, including their young.