DOI: 10.5061/dryad.2bvq83c2c
title: Data from:The foe you know: Observations of interspecific interactions between small cetaceans and northern resident killer whales (Orcinus orca) in the northeast Pacific

description: We documented the first aerial observations of interspecific interactions
 of fish-eating, northern resident killer whales (Orcinus orca) with two
 small cetacean species, Dall’s porpoises (Phocoenoides dalli) and Pacific
 white-sided dolphins (Lagenorhynchus obliquidens), off northeastern
 Vancouver Island, (British Columbia, Canada). Specifically, we used
 drone-collected data to compare observations of porpoises and dolphins
 interacting with northern resident killer whales to understand factors
 which may promote interspecific interactions. From 2018 to 2021, 42
 interactions were opportunistically recorded of Dall’s porpoises (19%),
 Pacific white-sided dolphins (74%), and both species (7%) approaching
 groups of travelling, milling, socializing, and resting northern resident
 killer whales. The mean group size of killer whales during interactions
 with dolphins (an average of 8 killer whales) and porpoises (an average of
 3 killer whales) was significantly different. Porpoises interacted only
 with small groups (n ≤ 5) of killer whales, while dolphins interacted with
 larger groups (n ≤ 25). This suggests that the likelihood of interaction
 by each species is influenced by killer whale group size. However, the age
 and sex composition of killer whale groups, as well as the number of small
 cetaceans present, were found to have no significant effect on interaction
 patterns. Additionally, we never observed killer whales initiating
 interactions. We discuss several adaptive benefits, including
 antipredator, foraging, hydrodynamic, and social advantages, to dolphins
 and porpoises which may drive the observed interactions. The benefits of
 interactions appeared to be predominantly antipredator-focused and
 species-specific, with both species possibly also benefitting from
 increased hydrodynamic efficiency whilst swimming. While opportunistic,
 our observations provide detailed accounts of non-predatory interactions
 between small cetacean species and northern resident killer whales. Future
 studies focusing on the drivers of mixed-species group formation in the
 North Pacific are needed, and we suggest that these utilize drones as a
 platform for data collection.
description: # The foe you know: Observations of interspecific interactions between
 small cetaceans and northern resident killer whales (*Orcinus orca*) in
 the northeast Pacific Dataset DOI:
 [10.5061/dryad.2bvq83c2c](10.5061/dryad.2bvq83c2c) ## Description of the
 data and file structure The Foe You Know: Observations of interspecific
 interactions between small cetaceans and northern resident killer whales
 (Orcinus orca) in the northeast Pacific **Authors** Brittany C.
 Visona-Kelly and Lance G. Barrett-Lennard **Purpose** Supplementary video
 files to accompany the publication titled above. **Usage Restrictions**
 The video files are published under the terms of the [CC0
 waiver](https://creativecommons.org/publicdomain/zero/1.0/). Please
 contact the lead author if you have any questions (see contact information
 below). **Citation** Visona-Kelly, B. C., & Barrett-Lennard, L. G.
 2025. The Foe You Know: Observations of interspecific interactions between
 small cetaceans and northern resident killer whales (*Orcinus orca*) in
 the northeast Pacific. *Ecology and Evolution*. **Approval** Drone flights
 were authorized by Fisheries and Oceans Canada (DFO, Research Licence
 2018-05(2), 2019-04 XMMS 4 2019) and approved by Transport Canada.
 **Contact Information** Ocean Wise Conservation Association is the
 provider of this dataset. Please contact Brittany Visona-Kelly (lead
 author) if you have any questions. Email:
 [Brittany.Visona@ocean.org](mailto:Brittany.Visona@ocean.org) ### Files
 and Descriptions #### File:
 Video\_S1\_-2021-07-08\_F10\_4\_-\_DP\_and\_logging\_whale.mp4
 **Description:** Two Dall’s porpoise approaching and circling a logging
 (i.e., resting) northern resident killer whale, 40-year-old adult female
 A43, on July 8, 2021, in Johnstone Strait, B.C., Canada. #### File:
 Video\_S2\_-2021-07-08\_F10\_10\_-\_DP\_and\_A69\_new\_calf\_socializing.mp4 **Description:** Dall’s porpoises travelling and socializing with northern resident killer whale A69 (24-year-old adult female) and her newborn calf A126 on July 8, 2021, in Johnstone Strait, B.C., Canada. #### File: Video\_S3\_-2018-09-06\_16-41-16-\_A61\_and\_PWSD.mp4 **Description:** Aggressive lunge displayed by 24-year-old adult male northern resident killer whale A61 during a Pacific white-sided dolphin interaction in Blackfish Sound, B.C., Canada on September 6, 2018. #### File: Video\_S4\_-2018-08-12\_13-43-54-\_NRKW-PWSD-DP\_interaction.mp4 **Description:** Example of Pacific white-sided dolphins and Dall’s porpoises swimming with northern resident killer whales in the northeastern Pacific. #### File: Video\_S5\_-2020-08-13\_F01\_1-\_PWSD\_and\_NRKW\_with\_fish.mp4 **Description:** Pacific white-sided dolphins approaching a northern resident killer whale carrying a fish in Blackfish Sound, B.C., Canada on August 13, 2020.