hostile nature, with the residents—who always outnumbered the transients—chasing their mammal-eating neighbors away. Scientists aren’t sure why, but they speculate that perhaps at some level the transients could pose a threat to the residents’ young calves. Not only was there no social overlap between the populations, but there was no communication between them, either. Resident orcas used an entirely different set of calls from transients when communicating and used them in entirely different fashions. It was a biologically unusual situation for two populations of the same species to occupy
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