Ladoga Ringed Seal (Pusa hispida ladogensis) Can Breed on Land: A Case Study of the Nursing Period

Abstract

The ringed seal gives birth and nurses offspring in a subnivean lair in fast ice. Its breeding habitat is transforming under the impact of climate change. Here we report the outcome of an observation of a female freshwater Ladoga ringed seal (Pusa hispida ladogensis) and her pup during the 2020 breeding season, when less than 1% of Lake Ladoga was covered with ice. We located a newborn pup in a coastal zone of an island and tracked its survival on land using the camera trap method during daylight. Altogether, we captured 2978 photos, in which the seals were present in 637. The female nursed the pup at the birth site for 34 – 37 days, which is similar to the lactation period in lairs of the Arctic subspecies (36 – 41 days, 39 days on average). The female either stayed with the pup or spent time in prolonged aquatic bouts during the day. Percentage of suckling was in the range of 2.4% – 4.7% (mean 3.3%, SD = 1.1) on different days. Based on an additional video recording, we found that the pup’s behaviour was characterized by a high level of vigilance in comparison with openly breeding phocid seals. This case study indicates that the ringed seal in Lake Ladoga is able to nurse pups on land from soon after birth to pre-weaning. However, breeding success in warm springs can be constrained by predator pressure.