Temporal variation in the vocal behaviour of southern right whales in the Auckland Islands, New Zealand

Autonomous recorders are frequently used for examining vocal behaviour of animals, and are particularly effective in remote habitats. Southern right whales are known to have an extensive acoustic repertoire. A recorder was moored at the isolated sub-Antarctic Auckland Islands for a year to examine w...

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Bibliographic Details
Published in:Royal Society Open Science
Main Authors: T. A. Webster, S. M. Van Parijs, W. J. Rayment, S. M. Dawson
Format: Article in Journal/Newspaper
Language:English
Published: The Royal Society 2019
Subjects:
Q
Online Access:https://doi.org/10.1098/rsos.181487
https://doaj.org/article/76f43be2c52c44df90e057839a257a13
Description
Summary:Autonomous recorders are frequently used for examining vocal behaviour of animals, and are particularly effective in remote habitats. Southern right whales are known to have an extensive acoustic repertoire. A recorder was moored at the isolated sub-Antarctic Auckland Islands for a year to examine whether the acoustic behaviour of southern right whales differed seasonally and throughout the day at their main calving ground in New Zealand. Recordings were made in each month except June, and vocalizations were audible in all months with recordings except January. A total of 35 487 calls were detected, of which upcalls were the most common (11 623). Call rate peaked in August (288 ± 5.9 [s.e.] calls/hour) and July (194 ± 8.3). Vocal behaviour varied diurnally with highest call rates detected at dusk and night, consistent with the concept that upcalls function primarily as contact calls. Zero-inflated model results confirmed that seasonal variation was the most important factor for explaining differences in vocal behaviour. An automated detector designed to expedite the analysis process for North Atlantic right whales correctly identified 80% of upcalls, although false detections were frequent, particularly when call rates were low. This study is the first to attempt year-round monitoring of southern right whale presence in New Zealand.