Journal Article
Occurrence of false killer whales ( Pseudorca crassidens ) and their association with common bottlenose dolphins ( Tursiops truncatus ) off northeastern New Zealand
Jochen R. Zaeschmar; Ingrid N. Visser; Dagmar Fertl; Sarah L. Dwyer; Anna M. Meissner; Joanne Halliday; Jo Berghan; David Donnelly; Karen A. Stockin
Marine Mammal Science · Vol. 30, Issue 2 · pp. 594-608 · 2014
Abstract
On a global scale, false killer whales ( Pseudorca crassidens ) remain one of the lesser‐known delphinids. The occurrence, site fidelity, association patterns, and presence/absence of foraging in waters off northeastern New Zealand are examined from records collected between 1995 and 2012. The species was rarely encountered; however, of the 61 distinctive, photo‐identified individuals, 88.5% were resighted, with resightings up to 7 yr after initial identification, and movements as far as 650 km documented. Group sizes ranged from 20 to ca . 150. Results indicate that all individuals are linked in a single social network. Most observations were recorded in shallow ( Tursiops truncatus ) were observed. Photo‐identification reveals repeat inter‐ and intraspecific associations among individuals with 34.2% of common bottlenose dolphins resighted together with false killer whales over 1,832 d. While foraging was observed during 39.5% of mixed‐species encounters, results suggest that social and antipredatory factors may also play a role in the formation of these mixed‐species groups.