Hyperoodon planifrons Flower 1882

5. Southern Bottlenose Whale Hyperoodon planifrons French: Baleine-a-bec australe / German: Sidlicher Entenwal / Spanish: Zifio calderén meridional Other common names: Antarctic Bottlenose, Flatheaded Bottlenosed Whale, Flower’s Bottle-nosed Whale, Pacific Beaked Whale Taxonomy. Hyperoodon planifrons Flower, 1882, “found upon the sea-beach of Lewis Island in the Dampier Archipelago, north-western Australia.” This species is monotypic. Distribution. Subantarctic and Antarctic waters from Antarctica to South Africa, S Australia, N New Zealand, and South America. Its occurrence appears to be relatively continuous within its distribution. Descriptive notes. Total length 650- 750 cm; weight ¢.6000-7500 kg. Unlike the closely related Northern Bottlenose Whale (H. ampullatus), there is no evidence that male Southern Bottlenose Whales are larger than females; however, this may be due to a lack of information because there are few accurate measurements of body length. Body is spindle-shaped, with greatest girth around its mid-point. Flukes are wide in relation to body length, and tailstock is compressed laterally. Dorsal fin is small and set approximately two-thirds of the distance between tip of the beak and end of the tail. Coloration is typically dark brown, dark gray, or black. Unlike many other species of beaked whales, Southern Bottlenose Whales do not seem to accumulate white linear scars from intraspecific aggression. Rostrum and lower jaw form a short but well-defined beak, and there are two grooves on the throat. There appears to be similar sexual dimorphism in shape of the forehead of the Southern Bottlenose Whale to that found in the Northern Bottlenose Whale, with the forehead of males becoming enlarged as they mature, but the Southern Bottlenose Whale does not develop large bony crests on maxillary bones of the skull, which is one of the most notable differences between the two species. Unlike many other species of beaked whales, adult male Southern Bottlenose Whales have no functional teeth and lack tusks that are one of the most distinctive features of the family Ziphiidae. Habitat. There is no specific information available for this species, but like all species of beaked whales, the Southern Bottlenose Whale is restricted to deeper oceanic waters. Food and Feeding. Southern Bottlenose Whales are known to consume a wide range of deep-water squid. They may consume deep-waterfish on occasion, but these do not appear to be an important part of their diet. In common with other species of beaked whales, feeding likely occurs at great depth, often over 500 m and possibly as deep as 3000 m or more. Foraging dives may be up to an hour in length. Breeding. There is no specific information available for this species, but based on information from the closely related Northern Bottlenose Whale, the Southern Bottlenose Whale is likely to reach sexually mature at c¢.7-11 years, and individuals may live as long as 37 years. Gestation is presumably about one year, and inter-birth intervals are unlikely to be shorter than two years. Activity patterns. There is no specific information available for this species, but if, as is the case in other species of beaked whales, they consume relatively small prey, individual Southern Bottlenose Whales have to spend a large proportion (60-70%) of their time foraging. Movements, Home range and Social organization. There is no specific information available forthis species, but it appears to occur in small groups of 1-4 individuals, with a maximum group size of ¢.20 individuals. Nothing is known about the composition of these groups. Status and Conservation. CITES Appendix I. Classified as Least Concern on The [UCN Red List. It has been estimated that there may be as many as 600,000 Southern Bottlenose Whales south of the Antarctic that convergence in summer months, and it is thought to be one of the most abundant deep-water predatorsin this region. Unlike the Northern Bottlenose Whale, the Southern Bottlenose Whale was not subjected to commercial whaling, and it is unlikely that its global population has been depleted. Like other species of beaked whales, the Southern Bottlenose Whale may be atrisk from anthropogenic activities such as overfishing of deep-water ecosystems. They may be caught as bycatch in driftnet fisheries and are potentially affected by noise pollution and climate change. Nevertheless, nothing is known about the form or extent of these potential impacts. Bibliography. Kasamatsu & Joyce (1995), MacLeod (2006, 2009), MacLeod & D'Amico (2006), MacLeod et al. (2006), Mead (1989a), Rice (1998).Published as part of Russell A. Mittermeier & Don E. Wilson, 2014, Ziphiidae, pp. 326-357 in Handbook of the Mammals of the World – Volume 4 Sea Mammals, Barcelona :Lynx Edicions on page 349, DOI: 10.5281/zenodo.660848