The development of cetacean sleep has not been explored fully. Questions such as whether cetacean mothers regulate their offspring’s resting behaviour and do resting behaviours change over the course of cetacean development remain unanswered. To address these questions, an investigation of the resting strategies and activity levels for four killer whale (Orcinus orca) calves and their mothers in managed care during free-swim conditions was conducted during the first three years of life. A series of interrelated hypotheses were assessed using three independent sets of archived data (24 h behaviour records, video recordings, and instantaneous sampling) collected from two facilities. Together, the results indicated that mothers adjusted their activity levels based on their calves’ current level of development. Floating, often a preferred resting behaviour, was rarely observed during the first post-parturition month for any of the mother–calf pairs. Rather, the mother–calf pairs tended to display fast-moving mother–calf swims with frequent trajectory changes as the calf gained swimming proficiency. Although floating occurred more frequently over time for all pairs, all four killer whale mother–calf pairs displayed a preference for a slower-paced pattern swim (i.e., swim-rest). Calves preferred to rest with their mothers over resting with others or independently. The similarities in resting strategies displayed by the killer whale mother–calf pairs housed in independent facilities without temporal overlap emphasizes the conserved nature and development of these strategies in a precocial cetacean species with extended maternal care.
The killer whale: foraging specializations and group hunting. — In:
Cetacean societies: field studies of dolphins and whales (
MannJ.ConnorR.C.TyackP.L.WhiteheadH., eds). The University of Chicago Press, Chicago, IL, p.
Observations on the early development of a captive bottlenose dolphin calf. — In:
The bottlenose dolphin (
LeatherwoodS.ReevesR.R., eds). Academic Press, San Diego, CA, p.
Underwater analysis of the behavioural development of free-ranging Atlantic spotted dolphin (Stenella frontalis) calves (birth to 4 years of age). —
Pregnancy is a drag: hydrodynamics, kinematics and performance in pre-and post-parturition bottlenose dolphins (Tursiops truncatus). —
J. Exp. Biol.214:
OlesiukP.F.EllisG.M.FordJ.K. (2005). Life history and population dynamics of northern resident killer whales (Orcinus orca) in British Columbia. — Canadian Science Advisory Secretariat Research Document 2005/045. Fisheries and Oceans Canada, Pacific Biological Station, Nanaimo, BC.
Infant development of two aquarium bottlenose dolphins. —
Asymmetry and symmetry in brain waves from dolphin left and right hemispheres: some observations after anesthesia, during quiescent hanging behavior, and during visual obstruction. —
Brain Behav. Evol.60: