Respiration Patterns of Southern Right Whale ( Eubalaena australis ) Mothers and Calves in Southern Brazil

Abstract

Respiration is a key physiological process in cetaceans, closely linked to energy expenditure, behavior, and physiological state. Using drone‐based surveys, we quantified respiration patterns of southern right whale ( Eubalaena australis ) mother–calf pairs in southern Brazil across two reproductive seasons (2020–2021). Based on over 100 h of observation from 43 identified pairs, we found marked differences between classes: respiration rates were 2.6‐fold higher in calves than their mothers, with median respiration rates of 1.8 and 0.7 breaths per minute, respectively. Respiration rates were significantly influenced by behavioral state, surface duration, and individual identity, decreasing during resting behavior and longer surface intervals. No statistically significant seasonal variation in respiration rates was detected. Comparative analyses revealed that lactating females in Brazil and Argentina exhibited similarly elevated respiration rates, both exceeding those reported for Australian females, suggest population‐level differences that are not solely explained by local environmental conditions. In contrast, calf respiration rates were highest in Argentina, potentially reflecting the combined effects of kelp gull harassment and colder water temperatures. Our findings demonstrate the sensitivity of respiration to behavioral, physiological, and environmental drivers and highlight the value of drone‐based observations for advancing physiological and conservation monitoring of baleen whales.

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