A novel foraging strategy
First, Bubbles would scan the environment using echolocation to identify a suitable target fish. The dolphin would then chase after that individual fish, ignoring the rest of the school. Bubbles mirrored the direction movement of his target, often following quite closely. The fish only escaped pursuit when it vomited, likely a stress response; Bubbles would then ingest the regurgitated food as the target fish swam away. Bubbles would repeat this process as much as 10 times in half an hour, and he only seems to do this with bigeye trevally. Nor does Bubbles eat the actual fish.
While dolphins usually forage in groups, and Bubbles has occasionally been spotted with other dolphins, he prefers to forage alone. This seems to be learned behavior, according to Haines; Bubbles developed a novel feeding strategy that requires less energy-intensive effort than chasing after fast-swimming prey. “We observed him repeating this behavior over several years, which suggests he may have learnt to target the fish with the fullest bellies, providing the most rewarding meals,” she said.
How can Bubbles even tell which fish have just eaten a satisfying meal? The authors think it might be related to echolocation during the scanning phase of the dolphin’s feeding strategy. Other species are known to use echolocation to tell the difference between species of fish, since different shapes will return differently structured echoes. The team did sample Bubbles’s vocalizations from the video footage and noted an intense sequence of clicks and low-frequency tones when engaged in kleptoparasitism. But it’s unclear whether he uses them to identify targets or to increase the target’s stress response.
This is also a small sample size (N=1) and a limited dataset, so more evidence is needed, preferably from other dolphins in the region, before one could conclude such behavior is common among the species, or whether Bubbles is just special. Haines and her co-authors believe this kleptoparasitic foraging behavior could be underestimated, given how difficult it is to capture occurrences on video in the wild.
“The use of technologies such as animal-borne video camera tags and unmanned aerial vehicles (drones) are likely to generate new insights into the cryptic behaviors of these elusive marine predators,” they concluded.
DOI: Ecology and Evolution, 2026. 10.1002/ece3.74270 (About DOIs).
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