ABS 2023
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Bubble-net feeding in Antarctic humpback whales: patterns in the use of a novel foraging innovation
Jennifer Allen1,2, Ross Nichols1, Logan Pallin1, David Cade1,3, Ari Friedlaender1. 1University of California Santa Cruz, Santa Cruz, CA, United States; 2Griffith University, Brisbane, QLD, Australia; 3Stanford University, Pacific Grove, CA, United States

Foraging innovations often allow species to respond to changing conditions. Humpback whales provide a good study species for this, as they utilize multiple novel foraging tactics across population with diverse conditions. Bubble-net feeding (BNF) has recently emerged as a foraging innovation within the Western Antarctic Peninsula population. Using sightings data from 2015-2023, we found BNF present in every study year, with an annual average of 30% of foraging sightings. BNF was significantly more common early in the feeding season before declining in latter months. This suggests that its use may be tied to specific environmental conditions such as prey density or light availability. Group sizes (mean = 3.41) were significantly larger for BNF sightings compared to other surface feeding tactics (mean = 2.26). Groups of three or more made up 56.6% of BNF sightings, while only 6% were single individuals. This is consistent with Northern Hemisphere populations, where BNF is also a group tactic. Social transmission of such foraging tactics across these other populations further suggests that BNF is also likely to be socially spread through the Western Antarctic Peninsula.