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The innovation and diffusion of novel foraging strategies within a population can increase the capacity of individuals to respond to shifts in prey abundance and distribution. Since 2011, some humpback whales (Megaptera novaeangliae) off northeastern Vancouver Island (NEVI), Canada, have been documented using a new feeding strategy called "trap-feeding." We provide the first description of this foraging innovation and explore the ecological and social variables associated with its diffusion using sightings data, video analysis, and logistic regression modeling. The number of humpback whales confirmed to trap-feed off NEVI increased from two in 2011 to 16 in 2015. Neither the locations of trap-feeding sessions nor prey species consumed differed from those documented during lunge-feeding. However, preliminary results indicate that the schools of fish consumed when individuals trap-fed were smaller and more diffuse than those consumed when whales lunge-fed. Top-ranked models predicting whether an individual would be observed exhibiting trap-feeding behavior included the following parameters: average number of days per year that the individual was seen off NEVI and proportion of the individual's associations that were with other trap-feeders. These results suggest that trap-feeding may be a culturally transmitted foraging innovation that provides an energetically efficient method of feeding on small, diffuse prey patches.

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Depredation of demersal longlines by killer and sperm whales is a widespread behaviour that impacts fisheries and whale populations. To better understand how depredating whales behave in response to fishing activity, we deployed satellite-linked location and dive-profile tags on a sperm and killer whale that were depredating Patagonian toothfish from commercial longlines off South Georgia. The sperm and killer whale followed one fishing vessel for >180 km and >300 km and repeatedly depredated when longlines were being retrieved over periods of 6 and 7 d, respectively. Their behaviours were also sometimes correlated with the depths and locations of deployed gear. They both dove significantly deeper and faster when depredating compared with when foraging naturally. The killer whale dove >750 m on five occasions while depredating (maximum: 1087 m), but these deep dives were always followed by long periods (3.9–4.6 h) of shallow (<100 m) diving. We hypothesize that energetically and physiologically costly dive behaviour while depredating is driven by intra- and inter-specific competition due to the limited availability of this abundant resource.

The route taken by northward migrating gray whales during spring between Vancouver Island and southeastern Alaska, a distance of about 575 km, has long been uncertain. It is generally believed that the whales closely follow the western, outer coastline of Haida Gwaii (formerly the Queen Charlotte Islands), an archipelago lying between Vancouver Island and southeastern Alaska, consistent with their pattern of migrating close to shore over the majority of their northward migratory corridor. By tracking satellite‐tagged individuals and surveying whales from shore bases, we provide evidence that this is not the primary migratory corridor, but instead that most whales migrate through Hecate Strait and Dixon Entrance, broad waterways that lie to the east and north of Haida Gwaii. By using this route, northbound gray whales potentially face a wider range of industrial activities and developments than they would by migrating along the outer coast.

Infanticide can be an extreme result of sexual conflict that drives selection in species in which it occurs. It is a rarely observed behaviour but some evidence for its occurrence in cetaceans exists in three species of dolphin. Here we describe observations of an adult male killer whale (Orcinus orca) and his post-reproductive mother killing a neonate belonging to an unrelated female from the same population in the North Pacific. This is the first account of infanticide reported in killer whales and the only case committed jointly by an adult male and his mother outside of humans. Consistent with findings in other social mammals, we suggest that infanticide is a sexually selected behaviour in killer whales that could provide subsequent mating opportunities for the infanticidal male and thereby provide inclusive fitness benefits for his mother.

Two populations of killer whales aggregate around Vancouver Island to feed primarily on Chinook salmon. Aerial photogrammetry of endangered southern residents has documented some adults growing to smaller lengths in recent decades, suggesting that early growth may have been constrained by low Chinook availability in the 1990s. We investigated whether growth and adult length were also constrained in the more abundant northern residents. Photographs were collected from an unmanned hexacopter at altitudes of 30 to 37 m over 4 yr, 2014 to 2017. Images were linked to 78 individuals of known age and sex based on distinctive saddle patch pigmentation. The length of each whale was estimated by measuring pixel dimensions between both the snout and dorsal fin and the dorsal fin and fluke; these were scaled to real size using camera lens focal length and altitude, determined by a laser or pressure altimeter. Total length, derived by summing the longest (flattest) of each measure, ranged from 2.42 m for a firstyear calf to 7.45 m for the largest adult male. A Bayesian change point analysis revealed that adult whales < 40 yr old were on average shorter by 0.44 m than older adults, which grew to typical lengths of 6.28 and 7.14 m for females and males, respectively. This mirrors the growth trends reported for southern residents, supporting demographic evidence of correlated prey limitation in both populations. The growth data suggest that the effects of nutritional stress are not only acutely lethal but also have long-term consequences for the condition of whales in both populations.

The extended female postreproductive life span found in humans and some toothed whales remains an evolutionary puzzle. Theory predicts demographic patterns resulting in increased female relatedness with age (kinship dynamics) can select for a prolonged postreproductive life span due to the combined costs of intergenerational reproductive conflict and benefits of late‐life helping. Here, we test this prediction using >40 years of longitudinal demographic data from the sympatric yet genetically distinct killer whale ecotypes: resident and Bigg's killer whales. The female relatedness with age is predicted to increase in both ecotypes, but with a less steep increase in Bigg's due to their different social structure. Here, we show that there is a significant postreproductive life span in both ecotypes with >30% of adult female years being lived as postreproductive, supporting the general prediction that an increase in local relatedness with age predisposes the evolution of a postreproductive life span. Differences in the magnitude of kinship dynamics however did not influence the timing or duration of the postreproductive life span with females in both ecotypes terminating reproduction before their mid‐40s followed by an expected postreproductive period of about 20 years. Our results highlight the important role of kinship dynamics in the evolution of a long postreproductive life span in long‐lived mammals, while further implying that the timing of menopause may be a robust trait that is persistent despite substantial variation in demographic patterns among populations.