Monitoring of the leopard seal population (Hydrurga leptonyx) in waters of the Argentine Islands (Antarctica)

• Published in: Theriologia Ukrainica
• Main Author: Pavlo B. Khoyetskyy
• Format: Article in Journal/Newspaper
• Language: English; Ukrainian
• Published: National Academy of Sciences of Ukraine. National Museum of Natural History 2020
• Subjects: hydrurga leptonyx; pygoscelis papua; lobodon carcinophagus; antarctica; population size; population structure; animal feeding; Zoology; QL1-991; Argentine; Argentine Islands; Hydrurga; Antarc*; Antarctica; Crabeater Seals; Hydrurga leptonyx; Leopard Seal; Leopard Seals; Lobodon carcinophagus; Pygoscelis papua
• Online Access: https://doi.org/10.15407/TU1916; https://doaj.org/article/e3d2ec13311a4849be54f03a0c724582

The state of the leopard seal population (Hydrurga leptonyx Blainville, 1828) in waters of the Argentine Islands was studied during the periods April 2015 — March 2016 and April 2018 — March 2019 according to the objectives of the State Target Scientific and Technical Research Programme of Ukraine in Antarctica for the period 2011–2020. During the study period, 14 males and 16 females were recorded within the archipelago (1M : 1.1F ratio). About 7 % of the seals were young individuals and more than 90% were adults. Leopard seals were recorded during all periods of the year. In the summer-autumn period, within the archipelago, there were 2 to 4 individuals simultaneously. The maximum period of stay of the predators in waters of the archipelago was about two weeks. Two individuals for at least two weeks were recorded twice in waters of the archipelago. The maximum period of absence of the seals in waters of the archipelago was 118 days. It was found that the occurrence of leopard seals and hence the traces of their life activities in various years were of different nature. In the autumn (April–May) of 2015, they were seen less frequently, on average every 6.3 ± 2.5 days, and in the autumn of 2018, on the contrary, more frequently, on average every 2.5 ± 0.5 days. The activity of the leopard seal in the winter (June, August) of 2015 decreased by half. It was recorded that the animals appeared in waters of the archipelago on average every 12.7 ± 5.5 days, and in the winter of 2018 — 5.5 ± 1.9 days. In the autumn of 2018, the predators and traces of their vital activities were seen less often — every 6.6 ± 1.6 days. During the study period, out of 78 recorded cases of the leopard seal’s occurrence, about 56 % of cases were recorded when they were on ice floes, in other cases (44 %) — when they were in water. In addition, several crabeater seals were recorded three times on an ice floe at an insignificant distance from a leopard seal. One of the main prey items for leopard seals within the archipelago are birds, in ...