Migratory insights from singing humpback whales recorded around central New Zealand.

Victoria E Warren,Michael Noad,Rochelle Constantine,Claire Garrigue,Ellen C Garland

doi:10.1098/rsos.201084

Abstract

The migration routes of wide-ranging species can be difficult to study, particularly at sea. In the western South Pacific, migratory routes of humpback whales between breeding and feeding areas are unclear. Male humpback whales sing a population-specific song, which can be used to match singers on migration to a breeding population. To investigate migratory routes and breeding area connections, passive acoustic recorders were deployed in the central New Zealand migratory corridor (2016); recorded humpback whale song was compared to song from the closest breeding populations of East Australia and New Caledonia (2015–2017). Singing northbound whales migrated past New Zealand from June to August via the east coast of the South Island and Cook Strait. Few song detections were made along the east coast of the North Island. New Zealand song matched New Caledonia song, suggesting a migratory destination, but connectivity to East Australia could not be ruled out. Two song types were present in New Zealand, illustrating the potential for easterly song transmission from East Australia to New Caledonia in this shared migratory corridor. This study enhances our understanding of western South Pacific humpback whale breeding population connectivity, and provides novel insights into the dynamic transmission of song culture.

Highlights

Large-scale animal movements, known as migrations, are commonly exhibited when a spatial disparity exists in the location of resources [1]
Autonomous passive acoustic instruments deployed in the marine environment of central New Zealand recorded singing humpback whales on their northward migration to western South Pacific breeding grounds from June until early August
Song detections revealed that the predominant migration route from the east coast of the South Island was through Cook Strait, rather than along the east coast of the North Island

Summary

Introduction

Large-scale animal movements, known as migrations, are commonly exhibited when a spatial disparity exists in the location of resources [1]. Recent studies using satellite tags, photographic mark–recapture and genetic analyses have revealed that humpback whales spread across a vast range of circumpolar longitudes during the feeding season and mix with whales from other breeding areas [2,5,11,15,16,17,18,19,20,21,22] This complexity in movement, in conjunction with limited resources to study their lengthy migration patterns, results in a paucity of understanding about the migratory routes of humpback whales that breed in the South Pacific

Objectives

Methods

Results

Discussion

Conclusion