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Occurrence of false killer whales ( Pseudorca crassidens ) and their association with common bottlenose dolphins ( Tursiops truncatus ) off northeastern New Zealand
Author(s) -
Zaeschmar Jochen R.,
Visser Ingrid N.,
Fertl Dagmar,
Dwyer Sarah L.,
Meissner Anna M.,
Halliday Joanne,
Berghan Jo,
Donnelly David,
Stockin Karen A.
Publication year - 2014
Publication title -
marine mammal science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.723
H-Index - 78
eISSN - 1748-7692
pISSN - 0824-0469
DOI - 10.1111/mms.12065
Subject(s) - foraging , biology , bottlenose dolphin , intraspecific competition , ecology , cetacea , zoology , geography , fishery
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 (<100 m) nearshore waters. Occurrence in these continental shelf waters is likely seasonal, coinciding with the shoreward flooding of a warm current. During 91.5% of encounters, close interspecific associations with common bottlenose dolphins ( 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.