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Why are many seal pups born on sea ice?

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A crabeater seal (Lobodon carcinophagus) lies on snow-covered ice with its mouth open, surrounded by broken sea ice in East Antarctica. — seal Crabeater seal (*Lobodon carcinophagus*).

Many seal species, such as the harp seal, rely on sea ice as a vital platform for giving birth and rearing their young.1

The primary reason for this behavior is that the ice serves as a necessary whelping platform, providing a stable environment for pups during their early development. For species like the harp seal, gestation is specifically timed to ensure that birth occurs when sufficient pack ice is available.1

This environment is critical for the survival of the pups, which are often born with a white coat for camouflage and lack the thick layer of blubber found in adults. While on the ice, these pups rely on their mothers' fat-rich milk to rapidly gain the blubber necessary for insulation and survival before they transition to independent feeding in the water. Other species, such as the ringed seal, further utilize this habitat by digging dens into the snow on the ice to protect their young.12