New Zealand orca facts

 

New Zealand orca researcher, Ingrid Visser, conducted a PhD research project, from 1992-1997, on the orca population in New Zealand.

Ingrid continues to research this population, made possible by funding from Adopt an Orca NZ. Research findings include (up to, and including, 1997):

  • 117 individual orca have been photo-identified in NZ waters. The population estimate ranges between 65 and 167.
  • 65% of groups were comprised of 11 or less animals, with an average group size of 4.5 animals (range = 2-22).
  • 83% of groups contained at least one calf and/or juvenile. · Some animals have been sighted exclusively in the South Island, some exclusively in the North Island, and others move between the two, suggesting three possible sub-populations.
  • Some individual animals have been known to travel up to 170 km per day on average. The largest known range of a NZ orca is 4200 km's.
  • Antarctic orca travel to NZ waters, as a group of animals sighted off the Bay of Islands in May 1997 had the pigmentation pattern of Antarctic orca.
  • Orca are most frequently seen in the Bay of Plenty/East Cape/Hawke's Bay region in June, and often from October to December.
  • Unlike British Columbia, the orca in NZ do not stay in large rigid pods, but appear to have a more fluid society comprised of smaller groups.
  • NZ orca feed on a variety of prey, the most common being rays (long-tailed and short-tailed stingrays, eagle rays, and torpedo rays), but also sharks (blue, mako, basking, and school sharks), a variety of fin-fish (yellow-fin tuna, bluenose grouper, kahawai, and sunfish), and a blue penguin on one occasion. NZ orca have also been observed attacking and consuming other cetacean species (common dolphins, bottlenose dolphins, dusky dolphins, Hector's dolphins, sperm whales, pilot whales, humpback whales, and southern right whales).
  • NZ orca are often observed 'food-sharing', most commonly ray species, but also other cetacean species, and occasionally fish species.
  • Each individual animal has unique eye-patches.