to forage mostly at depths of , but some have been observed by NOAA submersibles at a depth of . They prefer hunting in wide-open spaces, enabling them to use their speed more effectively. They are successful bottom-feeding hunters; some have even been observed lifting slabs of rock in search of prey. They have no natural predators. Reproduction and development Very little is known of the Mediterranean monk seal's reproduction. They are thought to be polygynous, with males being very territorial where they mate with females. Although no breeding season exists, since births take place year round, a peak occurs in October and November. This is also the time when caves are prone to wash out due to high surf or storm surge, which causes high mortality rates among pups, especially at the key Cabo Blanco colony. Pups make first contact with the water 2 weeks after their birth and are weaned around 18 weeks of age; females caring for pups go off to feed for an average of 9 hours. Most individuals are believed to reach maturity at 4 years of age. The gestation period lasts close to a year. However, monk seals of the Cabo Blanco colony may have a gestation period lasting slightly longer than a year. Mediterranean monk seals generally live to be 25 to 30 years old. Hawaiian monk seals are polygynous. The breeding season takes place throughout the year, excluding the fall, but peaks during April and May. Shark attacks cause a high pup mortality, from 19% to 39%. Pups are thought to be weaned around 6 weeks and reach sexual maturity at 3 years. Their typical lifespan is 25 to 30 years. Not much is known of the Caribbean monk seal's reproduction. They likely bore a single pup every two years. Their gestation period, lactation period, and sexual maturity age are unknown. Interactions with humans Hawaii Threats In the 19th century, many seals were killed by whalers and sealers for meat, oil, and skin. U.S. military forces hunted them during World War II, while occupying Laysan Island and Midway Island. Human disturbances have had immense effects on the populations of the Hawaiian monk seal. They tend to avoid beaches where they are disturbed; after continual disturbance, the seals may completely abandon the beach, thus reducing habitat size, subsequently limiting population growth. For instance, large beach crowds and beach structures limit the seal's habitat.