From a boat and from the air: size and composition of humpback whale groups estimated by onboard observers and drone videos

Authors

  • Anabela Miranda Departamento de Ciências Biológicas - Universidade Estadual de Santa Cruz (Ilhéus - Rodovia Jorge Amado, Km 16 - BA - Brazil)
  • Thomas Foucart Ecosul Turismo (Santa Luzia - Fazenda Santa Luzia - Estrada Santa Luzia, Km 14 - Una - 45865-000 - BA - Brazil)
  • Alice Lima Departamento de Ciências Biológicas - Universidade Estadual de Santa Cruz (Ilhéus - Rodovia Jorge Amado, Km 16 - BA - Brazil)
  • Kalyane Ramos Departamento de Ciências Biológicas - Universidade Estadual de Santa Cruz (Ilhéus - Rodovia Jorge Amado, Km 16 - BA - Brazil)
  • Yvonnick Le Pendu Departamento de Ciências Biológicas - Universidade Estadual de Santa Cruz (Ilhéus - Rodovia Jorge Amado, Km 16 - BA - Brazil)

DOI:

https://doi.org/10.1590/

Abstract

This study compared the size and composition of humpback whale groups estimated from boat-based observations and drone video analysis during the 2022 and 2023 breeding seasons in Ilhéus, Brazil. Data from 43 groups showed that drone consistently recorded larger group sizes than boat-based observations, with a strong positive correlation between the two methods (r=0.94, p<0.001). Drone also enabled more accurate identification of group composition, detecting additional individuals and more complex group types - such as large competitive groups - than the boat-based method. A significant association between method and group composition was found (p<0.001), with drones identifying more groups composed of four or more adults or a mother-calf pair with several escorts. These findings underscore the advantages of drone-based surveys for improving assessments of group structure, contributing to more accurate data to monitor and conserve cetacean populations.

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Published

12.12.2025

How to Cite

From a boat and from the air: size and composition of humpback whale groups estimated by onboard observers and drone videos. (2025). Ocean and Coastal Research, 73. https://doi.org/10.1590/