BREEDING BIOLOGY AND HAUL-OUT PATTERN OF THE NEW-ZEALAND FUR-SEAL, ARCTOCEPHALUS-FORSTERI, AT CAPE-GANTHEAUME, SOUTH AUSTRALIA

New Zealand fur seals, Arctocephalus forsteri, breed at Cape Gantheaum e (36 degrees 04'S,137 degrees 28'E), Kangaroo Island, South Australia , on broken rock platforms. In 1988-89, pups were born between late No vember and mid-January, 90% of them over 34 days between 3 December an d 6 January. The median date of birth was 21 December. A re-analysis o f data for this species from three breeding seasons at the Open Bay Is lands (South Island, New Zealand, 43 degrees 52'S,168 degrees 53'E) in dicates that: (i) the breeding season at Cape Gantheaume occurs 5-12 d ays later than at the Open Bay Islands, (ii) the period containing 90% of births was the same duration for both populations, and (iii) the m edian date of birth spanned seven days in three seasons at the Open Ba y Islands. In addition, the timing and duration of the pupping season varied within the Cape Gantheaume colony, it being later in recently c olonised areas. We suggest that this pattern is a consequence of chang es in the age distribution of females through the colony. The sex rati o of pups born in the colony over four breeding seasons did not differ significantly from 1:1. Females were mated on average 7.4 days after birth and left for sea 2.3 days later. The mean date of observed matin ,os was 29 December; copulations lasted about 13 min. The operational sex ratio (OSR) in the colony was 8.6 females per territorial male (th e maximum ratio of territorial males to pups was 1:16), which was with in the range reported for other southern fur seal species. In two cons ecutive breeding seasons, the estimated fecundity rate of adult female s averaged 67%. Non-breeding animals (sub-adult males, juveniles and y earlings) occurred in areas not occupied by breeding animals. The numb er of juveniles ashore increased after the breeding season, but no pat tern was found for sub-adults and yearlings. Yearlings were uncommon i n the colony at all times; it is suggested that they are mostly pelagi c and do not moult in their second year.