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Ramont, M., Smith, K. A., Muzzy, M., & Miller, L. J. (2026). Behavioral development in beluga whale (Delphinapterus leucas) and pacific white-sided dolphin (Aethalodelphis obliquidens) calves at the Shedd Aquarium. Animal Behavior and Cognition, 13(3), 303-318.  https://doi.org/10.26451/abc.13.03.06.2026

Knowledge of Odontocete developmental patterns is important for general comparative understanding and the implementation of informed husbandry policies. Although beluga whale (Delphinapterus leucas) calf behavioral development has previously been assessed in the literature, no previous studies have attempted to observe the behavioral development of Pacific white-sided dolphins (Aethalodelphis obliquidens). Seven beluga whale calves and four Pacific white-sided dolphin calves were observed for the first 30 days of life to determine the first occurrence and developmental trajectory of several typically monitored behaviors. Generalized linear mixed models (GLMMs) were used to evaluate the first 30 days for each behavior in successful calves. Beluga calves nursed for significantly longer duration (s/bout), but not frequencies (bouts/hr) compared to Pacific white-sided dolphins. Nursing duration was highest for belugas in the first 10 days of life, but otherwise nursing duration and frequency did not change significantly over time for belugas or Pacific white-sided dolphins. Overall respiration rates across the 30 days did not significantly differ between species, but beluga rates significantly increased over time while Pacific white-sided dolphin rates decreased. Pacific white-sided dolphins spent significantly more time associating with their dams and swimming in the slipstream position than belugas, and only Pacific white-sided dolphins saw significant decreases in these behaviors over time. The results of this study provide additional information regarding Odontocete developmental norms. Future research should continue to focus on calf behavioral development with the goal of increasing calf survival rates and promoting positive welfare in managed care.

Odontocete, Behavioral development, Beluga whale, Pacific white-sided dolphin, Nursing, Neonate