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Leopard seal (Hydrurga leptonyx)

Tracey L. Rogers (1), Jaume Forcada (2), Douglas J. Krause (3)

(1) Centre for Marine Science and Innovation & Evolution & Ecology Research Centre, School of BEES, University of New South Wales, Sydney, Australia
(2) British Antarctic Survey, Natural Environment Research Council (UKRI), Cambridge, UK.
(3) Antarctic Ecosystem Research Division, Southwest Fisheries Science Center, NOAA Fisheries, La Jolla, USA.

  • The IUCN Red List conservation status of the leopard seal is ‘Least Concern’. Nonetheless, sea-ice habitat loss, reduced krill stocks and increased fishing may combine to impact the species.
  • The last surveys of this species were in 1999/2000.
  • The leopard seal is the only animal among the Pinnipeds to hunt large vertebrate prey and yet also filter feed to eat small invertebrate prey.

Leopard seal (Hydrurga leptonyx) Order Carnivora, Family Phocidae.


The leopard seal has a circumpolar distribution in the Southern Ocean1, with the highest known densities in the Antarctic Peninsula2. Most leopard seals remain year-round in the Antarctic pack ice3,4 although some animals move north, out of the pack ice, to sub-Antarctic islands5,6,7 or occasionally further north.8 This is a non-breeding partial migration9, where migrants and non-migrants of the same population breed in the pack ice but overwinter at different locations. Most migrants are juveniles, regularly seen at sub-Antarctic islands, with the greatest numbers in September and October.1,10,11 The majority of migrants at sub-Antarctic islands are only observed on the one occasion, and only a few older individuals return multiple times. For these, migratory routes back to the pack ice may change from year to year. Vagrants are sighted in warm temperate latitudes, for example off eastern Australia, in winter months.1  Small resident populations also have been reported in New Zealand12, and Chile.8,13

Habitat and Ecology

Figure 1. Leopard seal predating on a juvenile fur seal. Image credit: Camile Toscani, British Antarctic Survey.

Female leopard seals are slightly larger (2.9 to 3.8 m and weighing up to 500 kg) than the males (2.8 to 3.3 m and weighing up to 300 kg).5 Pups are 1.0 to 1.6 m in length and weigh 30 to 35 kg at birth. The age at sexual maturity is probably four years for females and 4.5 years for males and longevity is estimated to be over 26 years.5

In the austral spring females haul out on the ice floes of the pack ice to give birth. Pups are born from late October to late December.13 The pups are weaned at approximately four weeks old, at which time the females are ready to mate (i.e., they go into oestrous).5 Mating has only been observed in captivity and occurs in the water.1

The leopard seal is the only known Pinniped both to hunt large vertebrate prey and also filter feed to eat small invertebrate prey.1 Leopard seals eat a wide range of different prey types,5,15,16 and their diet may vary based on their sex, body size17 and local food availability.

Leopard seals that hunt large vertebrates, for example other seals,18,19,20,21 penguins17,22 and large fish,17,18 need to break apart these large meals into smaller pieces to swallow.1 This is difficult for a marine predator where the prey cannot be held between flippers and partly why marine mammals feed typically on small prey that is swallowed whole. Leopard seals process large prey at the water’s surface by gripping a carcass with their teeth and thrashing it in an arc to tear smaller pieces away for consumption.1

Leopard seals hunt Antarctic fur seals,17,19 southern elephant seals,21 Weddell seals18 and crabeater seals.18 Young crabeater seals are probably the most frequently attacked, indeed 78% of crabeater seals have parallel scars suggesting escape from a leopard seal attack.23 Young, newly fledged naïve penguins are most vulnerable, but adult birds are taken as well. Birds are ambushed as they transit to and from colonies.22 This includes chinstrap, Adélie, gentoo, king, emperor, rockhopper, and macaroni penguins. They can also prey on flying seabirds of any size, from diving petrels to giant petrels as well as on fish and squid.18,24 Leopard seals also feed on small prey, like Antarctic krill,17,18,24 and use suction and filter feeding when hunting these small prey.25

In the Antarctic Peninsula and sub-Antarctic Islands (e.g., Bird Island), leopard seals may have a significant role in driving population dynamics of their prey species, such as the Antarctic fur seal.17,26,27 Where multiple prey is available, they tend to consume the most abundant prey species, depending on prey availability and seasonality, which in turn relates to the time the individual leopard seals spend at a particular location.27 While leopard seals have been preyed upon by killer whales, such observations are rare.1

Figure 2. Leopard seals resting on an ice floe. Image credit: Camile Toscani, British Antarctic Survey.


The conservation status of the leopard seal was assessed in 2015 as ‘Least Concern’ under the IUCN Red List Criteria.28 The justification for this classification was: widespread distribution; circumpolar estimate of leopard seal abundance (conducted in 1999/2000) of more than 35,000 individuals; and no indication of population decline. Caution was noted, however, as population estimates are substantial underestimates, with considerable uncertainty, consequently population trends are unknown, further, as leopard seals depend on sea ice for reproduction, they could be adversely affected by a future reduction in sea ice due to continued climate warming4.

International management of the leopard seal falls under the auspices of various agreements that are part of the Antarctic Treaty System; notably measures adopted at Antarctic Treaty Consultative Meetings, the Protocol on Environmental Protection to the Antarctic Treaty (Madrid, 1991), and the Convention for the Conservation of Antarctic Seals (CCAS; London 1972).

Annex II to the Protocol on Environmental Protection to the Antarctic Treaty (1991), provides for the conservation of Antarctic fauna and flora, and prohibits taking or harmful interference with native fauna and flora except in accordance with a permit.  Annex II also provides for the conditions under which permits should be issued which includes scientific research (as per Article 4 of CCAS).

The Convention for the Conservation of Antarctic Seals (CCAS), under the Antarctic Treaty, was signed on 1 June 1972, and entered into force in 1978, and aims to protect the stocks of Antarctic seals, including the leopard seal, from commercial exploitation. Although the leopard seal has never been part of a commercial harvest, Annex I of CCAS provides for commercial harvests of a limited numbers of leopard seals, with a global quota of 12,000 animals annually.

Article 4 of CCAS allows for special permits to be issued for scientific research to take a small number of leopard seals to collect information on life history and ecology that might provide a basis for conservation and management within the framework of the Antarctic Treaty.

Figure 3. Leopard seal chasing penguin. Image credit: John Dickens, British Antarctic Survey.

Interactions with humans

Attacks on humans by leopard seals are rare, and only one event has been fatal.29 In the sea ice in Eastern Antarctica researchers report being ambush-hunted by leopard seals, whereas divers in the Antarctic Peninsula report non-harmful interactions. Leopard seals are reported to be attracted to the vibrations of outboard motors and bite the oars and pontoons of rigid inflatable boats; however, if hunting and territorial behaviours are avoided danger to humans is likely minimal.30


In the western Antarctic Peninsula, the region of highest leopard seal densities, the seals’ sea-ice habitat has decreased by 21–28%.2 Alongside this habitat loss, there has been a decline in krill in the region, and an increase in fishing pressure, which could indirectly reduce leopard seal food.2 These factors may combine to potentially impact the leopard seal.

The high dependence on sea ice as a primary breeding and resting platform makes the leopard seal vulnerable to changes in the sea ice environment. Long-term changes in the seasonal sea ice extent as driven by climate can affect the availability of a proper breeding environment and also affect access to food where Antarctic krill is a main prey for the Antarctic food web. Changes in the sea ice environment also affect the migration timing, the number of migrants and the time that those chose to stay in their temporary non-breeding grounds.31 This in turn may have consequences for the population dynamics of prey consumed.

Circumpolar aerial and shipboard surveys were last conducted in 1999/2000 and at the time were believed to underestimate the true leopard seal population.2,32,33,34 The leopard seal is difficult to study via traditional ship-based visual surveys32,34 due to the fact that when surveys are conducted (in the austral spring/summer) seals sing underwater34,35 and are unavailable to visual surveys.32,34 However, as the leopard seals produce loud36 vocalisations in a regular pattern37 for many hours, passive acoustic monitoring provides a cost-effective method,34 alongside traditional techniques, to identify spatial distribution and habitat use.34 In parallel, small unoccupied aerial systems (a.k.a., drones) can provide accurate, scalable platforms that can greatly increase spatial and temporal survey coverage.38,39,40

  • The leopard seal has a circumpolar distribution with highest densities off western Antarctic Peninsula.
  • Sea-ice habitat loss, reduced krill stocks and increased fishing may combine to potentially impact the leopard seal.
  • Assessing the full impact of environment change on the species is restricted by poor knowledge of the population status and trends. The last surveys of this species were in 1999/2000, and an update of population estimates is urgently needed.

Other information:

  1. T.L. Rogers, Leopard seal: Hydrurga leptonyx. In Encyclopedia of marine mammals (Academic Press, New York, 2018) pp. 550-552 doi:
  2. J. Forcada, P.N. Trathan, P.L. Boveng, I.L. Boyd, J.M. Burns, D.P. Costa, M. Fedak, T.L. Rogers, C.J. Southwell (2012) Responses of Antarctic pack-ice seals to environmental change and increasing krill fishing. Biology Conservation 149, 40–50 (2012) doi:
  3. T. L. Rogers, C.J. Hogg, A. Irvine, Spatial movement of adult leopard seals (Hydrurga leptonyx) in Prydz Bay, Eastern Antarctica. Polar Biology 28, 456–463 (2005) doi:
  4. J. Meade, M.B. Ciaglia, D.J. Slip, J. Negrete, M.E.I. Márquez, J. Mennucci, T.L. Rogers, Spatial patterns in activity of leopard seals Hydrurga leptonyx in relation to sea ice. Marine Ecology Progress Series 521,265–275 (2015) doi:
  5. T. L. Rogers, Leopard seal: Hydrurga leptonyx. In Encyclopedia of marine mammals (Academic Press, New York, 2009) pp. 673-674 doi:
  6. E. S. Nordøy, A.S. Blix, Movements and dive behaviour of two leopard seals (Hydrurga leptonyx) off Queen Maud Land, Antarctica. Polar Biology 32,263–270 (2009) doi:
  7. I. J. Staniland, N. Ratcliffe, P.N. Trathan, J. Forcada, Long term movements and activity patterns of an Antarctic marine apex predator: The leopard seal. PLoS ONE 13, e0197767 (2018) doi:
  8. A. Aguayo-Lobo,  J. Acevedo, J.L. Brito., P. Acuna, M. Bassoi, E.R. Secchi. 2011. Presence of the leopard seal, Hydrurga leptonyx (de Blainville, 1820) on the coasts of Chile: an example of the Antarctic and South America connection in the marine environment. Oecología Australis (Special Edition) 15(1): 69-85. doi: 10.4257/oeco.2011.1501.07.
  9. A.K. Shaw, S.A. Levin, To breed or not to breed: a model of partial migration. Oikos 120, 1871-1879 (2011).
  10. T.R. Walker, I.L. Boyd, D.J. McCafferty, N. Huin, R.I. Taylor, K. Reid, Seasonal occurrence and diet of leopard seals (Hydrurga leptonyx) at Bird Island, South Georgia. Antarctic Science 10, 75-81 (1998) doi:
  11. M. J. Jessopp, J. Forcada, K. Reid, P.N. Trathan, E.J. Murphy, Winter dispersal of leopard seals (Hydrurga leptonyx): environmental factors influencing demographics and seasonal abundance. Journal of Zoology 263, 251-258 (2004) doi:
  12. K. Hupman, I.N. Visser, J. Fyfe, M. Cawthorn, G. Forbes, A.A. Grabham, R. Bout, B. Mathias, E. Benninghaus, K. Matucci, T. Cooper, L. Fletcher, D. Godoy. From vagrant to resident: occurrence, residency and births of leopard seals (Hydrurga leptonyx) in New Zealand waters. New Zealand Journal of Marine and Freshwater Research 54, 1-23 (2020) doi:
  13. J. Acevedo, A. González, S. Garthe, I. González, R. Gómez, A. Aguayo-Lobo. Births of leopard seals Hydrurga leptonyx in southern Chile. Polar Biol 40, 713–717 (2017).
  14. C. Southwell, K. Kerry, P. Ensor, E.J. Woehler, T. Rogers, The timing of pupping by pack-ice seals in East Antarctica. Polar Biology 26, 648-652 (2003) doi:
  15. A. I. Guerrero, J. Negrete, M.E.I. Márquez, J. Mennucci, K. Zaman, T.L. Rogers, Vertical fatty acid composition in the blubber of leopard seals and the implications for dietary analysis. Journal Experimental Marine Biology 478,54-61 (2016) doi:
  16. S. Botta, E.R. Secchi, T.L. Rogers, J.H. Prado, R.C. de Lima, P. Carlini, J. Negrete, Isotopic niche overlap and partition among three Antarctic seals from the western Antarctic Peninsula. Deep-Sea Research II 149, 240–249 (2018) doi:
  17. D. J. Krause, M.E. Goebel, C.M. Kurle, Leopard seal diets in a rapidly warming polar region vary by year, season, sex, and body size. BMC Ecology 20, 32 (2020).
  18. S.A. Hall-Aspland, T.L. Rogers, Summer diet of leopard seals (Hydrurga leptonyx) in Prydz Bay, Eastern Antarctica. Polar Biology 27, 729 –734 (2004) doi:
  19. L.M. Hiruki, M.K. Schwartz, P.L. Boveng, Hunting and social behaviour of leopard seals (Hydrurga leptonyx) at Seal Island, South Shetland Islands, Antarctica. Journal of Zoology 249, 97-109 (1999). https://doi:10.1111/j.1469-7998.1999.tb01063.x
  20. D. Krause, M. Goebel, G. Marshall, K. Abernathy, Novel foraging strategies observed in a growing leopard seal (Hydrurga leptonyx) population at Livingston Island, Antarctic Peninsula. Animal Biotelemetry 3,24 (2015) doi:
  21. D.J. Krause, T.L. Rogers, Food caching by a marine apex predator, the leopard seal (Hydrurga leptonyx). Canadian Journal Zoology 97, 573–578 (2019) doi:
  22. T. Rogers, M.M. Bryden, 1995. Predation of Adélie penguins (Pygoscelis adeliae) by leopard seals (Hydrurga leptonyx) in Prydz Bay, Antarctica. Canadian Journal of Zoology 73, 1001-1004 (1995) doi:
  23. D.B. Siniff, J.L. Bengtson, Observations and hypotheses concerning the interactions among crabeater seals, leopard seals, and killer whales. Journal of Mammalogy 58, 414-416 (1977).
  24. L.F. Lowry, J.W. Testa, W. Calvert, Notes on winter feeding of crabeater and leopard seals near the Antarctic Peninsula. Polar Biology 8, 475–478 (1988) doi:
  25. D.P. Hocking, A.R. Evans, E.M. Fitzgerald, Leopard seals (Hydrurga leptonyx) use suction and filter feeding when hunting small prey underwater. Polar Biology 36, 211-222 (2013) doi:
  26. P.L. Boveng, L.M. Hiruki, M.K. Schwartz, J.L. Bengtson, Population growth of Antarctic fur seals: limitation by a top predator, the leopard seal? Ecology, 79, 2863-2877 (1998). doi:10.1890/0012-9658(1998)079[2863:PGOAFS]2.0.CO;2
  27. J. Forcada, D. Malone, J.A. Royle, I.J. Staniland, Modelling predation by transient leopard seals for an ecosystem-based management of Southern Ocean fisheries. Ecological Modelling 220, 1513-1521 (2009).
  28. L. Hückstädt, Hydrurga leptonyx. The IUCN Red List of Threatened Species e.T10340A45226422 (2015). doi:
  29. S.F. Muir, D.K.A. Barnes, K. Reid, Interactions between humans and leopard seals. Antarctic Science 18, 61–74 (2006). doi:
  30. T.E. DeLaca, J.H. Lipps, G.S. Zumwalt. 1975. Encounters with leopard seals (Hydruga leptonyx) along the Antarctic Peninsula. Antarctic Journal of the United States. X(3).
  31. J. Forcada, I. Staniland, Leopard seal migration phenology responds to long-term variation in sea ice extent. World Marine Mammal Science Conference, December 9-12, 2019, Barcelona, Spain. Book of Abstracts, Pages 242-243 (2019).
  32. C. Southwell, C.G. Paxton, D. Borchers, P. Boveng, T. Rogers, K. William, Uncommon or cryptic? Challenges in estimating leopard seal abundance by conventional but state-of-the-art methods. Deep-Sea Res I 55, 519–531 (2008) doi:
  33. J.L. Bengtson, J.L. Laake, P.L. Boveng, M.F. Cameron, M.B. Hanson, B.S. Stewart, Distribution, density, and abundance of pack-ice seals in the Amundsen and Ross Seas, Antarctica. Deep-Sea Research II 58,1261−1276 (2011) doi:
  34. T.L. Rogers, M.B. Ciaglia, H. Klinck, C. Southwell, Density can be misleading for low-density species: Benefits of passive acoustic monitoring. PLoS ONE 8, e52542 (2013) doi:
  35. I. van Opzeeland, S. van Parijs, H. Bornemann, S. Frickenhaus, L. Kindermann, H. Klinck, J. Plötz, O. Boebel, Acoustic ecology of Antarctic pinnipeds. Marine Ecology Progress Series 414, 267–291 (2010) doi:
  36. T.L. Rogers, Source levels of the underwater calls of a male leopard seal. Journal Acoustic Society America 136, 1495–1498 (2014) doi:
  37. T.L. Rogers, Calling underwater is a costly signal: size-related differences in the call rates of Antarctic leopard seals. Current Zoology 63, 433-443 (2017) doi:
  38. K.L. Sweeney, V.T. Helker, W.L. Perryman, D.J. LeRoi, L.W. Fritz, T.S. Gelatt, et al. Flying beneath the clouds at the edge of the world: using a hexacopter to supplement abundance surveys of Steller sea lions (Eumetopias jubatus) in Alaska Journal of Unmanned Vehicle Systems 4,70–81 (2015).
  39. C. Pfeifer, A. Barbosa, O. Mustafa, H-U. Peter, M-C. Rümmler, A. Brenning. Using Fixed-Wing UAV for Detecting and Mapping the Distribution and Abundance of Penguins on the South Shetlands Islands, Antarctica. Drones 3(2):39 (2019).
  40. D.J. Krause, J.T. Hinke, W.L. Perryman, M.E. Goebel, D.J. LeRoi, An accurate and adaptable photogrammetric approach for estimating the mass and body condition of pinnipeds using an unmanned aerial system. PLOS ONE 12, e0187465 (2017). doi:


IUCN Red List of Threatened Species entry for leopard seals: