Leopard seals are pagophilic, "ice-loving" seals, which primarily inhabit the Antarctic pack ice between 50˚S and 80˚S. Sightings of vagrant leopard seals have also been recorded on the coasts of Australia, New Zealand, South America, and South Africa. In August 2018 an individual was sighted in Geraldton on the west coast of Australia. Higher densities of leopard seals are seen in the Western Antarctic than in other regions. Most leopard seals remain within the pack ice throughout the year and remain solitary during most of their lives with the exception of a mother and her newborn pup. These matrilineal groups can move further north in the austral winter to sub-antarctic islands and the coastlines of the southern continents to provide care for their pups. While solitary animals may appear in areas of lower latitudes, females rarely breed there. Some researchers believe this is due to safety concerns for the pups. Lone male leopard seals hunt other marine mammals and penguins in the packed ice of antarctic waters. The estimated population of this species ranges from 220,000 to 440,000 individuals, which puts leopard seals at "least concern". Although with an abundance of leopard seals in the antarctic, they are difficult to survey by traditional visual techniques because they spend long periods of time vocalizing under the water during the austral spring and summer when visual surveys are carried out. This trait of vocalizing underwater for long periods has made them available to acoustic surveys, allowing researchers to gather most of what is known about them.