Linking early diving proficiency from maternal behavior adjustment in Weddell seals: Insights from mother-pup pairs at Terra Nova Bay, Ross Sea, Antarctica

Weddell seal ( Leptonychotes weddellii ) pups undergo rapid growth and learn critical diving skills for independent survival during the lactation period. We investigated the diving behavior of Weddell seal mother-pup pairs using time-depth recorders during the early breeding seasons of November 2022 and 2023 in Terra Nova Bay, Ross Sea, Antarctica. A total of 7297 dives were recorded from 17 mother-pup pairs. Overall, mothers performed significantly longer and deeper dives than pups, whereas post-dive surface recovery times were similar between mothers and pups. In contrast, when comparing paired dives between mothers and pups, they exhibited similar dive durations and maximum depths. Notable similarities in the temporal patterns of dive frequency were observed between mothers and pups with peak diving frequencies. In addition, dive durations and maximum depths got progressively increased in both mothers and pups, and this pattern indicated that pups showed gradual improvement in their diving capacity. Notably, mothers engaged in more foraging dives during solo dives, which were significantly deeper and longer than paired dives. The results of our study suggest that mothers adjust their diving behavior to support pup development through synchronized diving, while maintaining their own foraging needs through opportunistic solo dives. This study highlights a mixed capital–income breeding strategy that demonstrates a trade-off between maternal behavior adjustment and self-maintenance in nursing mothers. Our results provide early diving development in Weddell seals and the ecological role of synchronized diving behavior in mother-pup pairs. • We investigated diving behavior of Weddel seal mother-pup pairs. • In total, 7297 dives were noted from 17 pairs using time-depth recorders. • Mothers were observed to perform significantly longer and deeper dives than pups. • Pups showed gradual improvement in diving over synchronized dive periods. • Results highlight ecological role of synchronized diving behavior in mother-pup pairs in this species.