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Development of intentional stranding hunting techniques in killer whale (Orcinus orca) calves at Crozet Archipelago
Canadian Journal of Zoology
Abstract
This paper describes the trend in the practice of what we interpret to be the ''intentional stranding'' hunting technique of two juvenile female killer whales (Orcinus orca), A4 and A5, belonging to pod A on the beaches of Possession Island, Crozet Archipelago. Pod A was composed of three adult females, A2, A3, A6, and one adult male, A1. A2 is A4's mother and A3 is A5's mother. The year of birth and thus the probable age of the two juveniles were estimated from their growth curve determined by means of a photogrammetric technique. These observations indicate that at Crozet Archipelago, juvenile killer whales first practiced intentional stranding on their own when they were 4-5 years old. Their first attempt to capture elephant seal pups by means of this technique was observed when they were 5-6 years old. However, 5- to 6-year-old juveniles still needed the assistance of an adult female to return to the water with their prey. This study indicates that learning hunting techniques needs a high degree of skill and requires high parental investment to reduce the associated risk. Furthermore, social transfer, through apprenticeship, is probably one of the mechanisms that enables the high degree of adaptability observed in killer whales.
... Another example of sex-based foraging strategies was observed with different killer whale populations that beach themselves to catch penguins, seals, or sea lions [47][48][49]). In one population, only females beach themselves [47,48], whereas in another population males and females beach themselves [49]. ...
... Another example of sex-based foraging strategies was observed with different killer whale populations that beach themselves to catch penguins, seals, or sea lions [47][48][49]). In one population, only females beach themselves [47,48], whereas in another population males and females beach themselves [49]. While two populations of bottlenose dolphins also display a beaching technique to chase fish onto mud flats, sex differences have not been reported (i.e., strand feeding [50][51][52]). ...
... Atlantic bottlenose dolphins off the coast of South Carolina have been observed beaching themselves onto mudflats in pursuit of fish that have been driven there by dolphins [50]. Similarly, two different, geographically isolated killer whale populations have invented slightly different beaching techniques in which individuals pursue penguins, seals, or sea lions onto beaches [47][48][49]. These foraging examples illustrate that delphinids are not only curious, but inventive when faced with a foraging challenge. ...
Simple Summary
Creative or novel behaviors in bottlenose dolphins (Tursiops truncatus) can be indicators of flexible thinking and problem solving. Twelve bottlenose dolphins (five females, seven males) in managed care were reinforced for exhibiting different behaviors of their choosing in response to a hand gesture. Using a human-based theory of creativity, the dolphins’ behaviors were assessed for four aspects: how many different behaviors they could produce in a session or in a row (fluency), how different the behaviors were from each other (flexibility), how simple or complex the behaviors were (elaboration), and how novel or new the behaviors were (originality). The results indicated that dolphins were variable in all aspects measured, with some animals producing more behaviors that were also more complex and variable in type and energy than the other dolphins. Behaviors were also invented by several dolphins. The dolphins were engaged and cognitively challenged by this task, which suggests this task facilitates cognitive welfare while providing a means to study innovative behavior across species.
Abstract
Creative or novel behaviors in bottlenose dolphins (Tursiops truncatus) can be indicators of flexible thinking and problem solving. Over 50 years ago, two rough-tooth dolphins demonstrated creative novel behaviors acquired through reinforcement training in human care. Since this novel training, a variety of species have been trained to respond to this conceptual cue. The current study assessed the creativity of 12 bottlenose dolphins (5 females, 7 males) housed at the Roatan Institute for Marine Sciences (RIMS) in Roatan, Honduras. Individual differences were found across four constructs measured for creativity: fluency, flexibility, elaboration, and originality. Variability in performance occurred across test sessions. Animals with less experience with this task performed fewer “innovative” behaviors as compared to more experienced animals. Despite errors, dolphins continued to attempt the task during test sessions, suggesting the concept of “innovate” was intrinsically rewarding and cognitively engaging. This task may be utilized across species to promote the comparative study of innovative or creative behavior as well as to promote cognitive welfare.
... Both juvenile and adult female elephant seals are presumably profitable prey due to their ease of capture and high energy-rich blubber, and may be an important seasonal prey species for killer whales in Monterey Bay or during periods when the whales are foraging in offshore waters [1,16,32,55]. The importance of elephant seals as prey for mammal-eating killer whales has been extensively studied in the southern hemisphere, with observations of whales primarily feeding on southern elephant seals (Mirounga leonine), while using similar predatory and feeding behaviours as we have described [56][57][58]. ...
... Predatory behaviours required to subdue grey whale calves are likely complex and risky, and may require a long and steep learning curve for calves and juveniles that require time to obtain knowledge by observing and participating in hunts with experienced adult females. This is consistent with the high parental investment made in developing the skills of juvenile killer whales in the Crozet Islands to successfully capture southern elephant seals using the high-risk behaviour of intentional stranding [56]. ...
Transient killer whales have been documented hunting marine mammals across a variety of habitats. However, relatively little has been reported about their predatory behaviours near deep submarine canyons and oceanic environments. We used a long-term database of sightings and encounters with these predators in and around the Monterey Submarine Canyon, California to describe foraging behaviour, diet, seasonal occurrence, and habitat use patterns. Transient killer whales belonging to the outer coast subpopulation were observed within the study area 261 times from 2006–2021. Occurrences, behaviours, and group sizes all varied seasonally, with more encounters occurring in the spring as grey whales migrated northward from their breeding and calving lagoons in Mexico (March-May). Groups of killer whales foraged exclusively in open water, with individuals within the groups following the contours of the submarine canyon as they searched for prey. Focal follows revealed that killer whales spent 51% of their time searching for prey (26% of their time along the shelf-break and upper slope of the canyon, and 25% in open water). The remainder of their time was spent pursuing prey (10%), feeding (23%), travelling (9%), socializing (6%), and resting (1%). Prey species during 87 observed predation events included California sea lions, grey whale calves, northern elephant seals, minke whales, common dolphins, Pacific white-sided dolphins, Dall’s porpoise, harbour porpoise, harbour seals, and sea birds. The calculated kill rates (based on 270 hours of observing 50 predation events) were 0.26 California sea lions per killer whale over 24 hours, 0.11 grey whale calves, and 0.15 for all remaining prey species combined. These behavioural observations provide insights into predator-prey interactions among apex predators over submarine canyons and deep pelagic environments.
... Our suggestion is further corroborated by mother-calf observations made by Hamel, Torres Ortiz, and Wahlberg (in press). Learning is fundamental for some odontocete foraging behaviours (Sargeant and Mann 2009;Baird 2000;Guinet and Bouvier 1995;Weiss 2006) and mothers have a key role in transmission of behavioural strategies to their calves (Bender, Herzing, and Bjorklund 2009;Sargeant et al. 2005). ...
Opportunistic mobile predators can adapt their behaviour to specific foraging scenarios, allowing them to target diverse prey resources. An interesting example is the harbour porpoise (Phocoena phocoena), a marine mammal with a huge energy demand feeding on a large variety of fish, squid and shrimps. Little is known about the foraging behaviour of harbour porpoises, as observations of wild specimens are notoriously difficult to obtain. In this study, foraging was identified in almost 60% of videos from UAV recordings in Danish coastal waters during daylight hours. Observations reveal them to be flexible predators, foraging on both single fish and schools of fish, as well as individually and in groups of varying sizes. We argue that some of the observed behavioural adaptations and context‐dependent strategies for prey capture are based on information transfer and social learning. Our results provide unprecedented insights into the foraging behaviour of an opportunistic mammalian predator. Furthermore, this study highlights the importance of porpoises having access to coastal areas for energy acquisition, where they are in conflict with anthropogenic disturbances such as fisheries with the risk of bycatch.
... Synchronous swimming with one or more partners is often described as an affiliative behavior in bottlenose dolphins (Tursiops sp, Connor et al., 2006;Fellner et al., 2013;Clegg et al., 2017). These behaviors may involve tactile interactions (Sakai et al., 2016) and could facilitate social learnings of prey capture (Bender et al., 2009;Guinet and Bouvier, 1995). But probably the most extensively studied prosocial behavior in cetacean is cooperation. ...
Cognitive enrichments have gained popularity in the past two decades in both farm animal and zoological settings. In this study, we present a cognitive enrichment device that, for the first time, allowed testing for prosocial food-sharing actions in dolphins. The device was made of a PVC tube and two caps with rope handles; one handle was fixed to the poolside whereas the other was available for the dolphins. Its internal structure kept five fish in place while maintaining a closed status. The dolphin who pulled the rope handle could not access the fish but allowed another individual to access it. Once the handle was released, however, the device closed back. The device was tested with a male and a female group, separately. The males obtained approximately a third, while the females acquired none of the fish using the device. Moreover, the males were observed to open the device more frequently and longer in the presence of their group members and with consistent roles. These results provide the first support of male dolphins’ willingness to engage in food-sharing that could be considered as an altruistic action. It also provides basis for further investigations on more detailed and long-term monitoring of the emergence and consequences of such cooperative actions.
... However, because feeding behaviours are culturally transmitted within kin-based killer whale groups (e.g. [63]), the presence of clusters of highly associated, genetically related whales sharing the same diet in our data was likely a consequence, rather than a driver, of association-i.e. a result of cultural diffusion in the network (see [18]). Nevertheless, we cannot rule out some level of true social assortment by diet, as preferentially associating with others that adopt similar feeding techniques can provide benefits for cooperative behaviours [5]. ...
Philopatric kin-based societies encourage a narrow breadth of conservative behaviours owing to individuals primarily learning from close kin, promoting behavioural homogeneity. However, weaker social ties beyond kin, and across a behaviourally diverse social landscape, could be sufficient to induce variation and a greater ecological niche breadth. We investigated a network of 457 photo-identified killer whales from Norway (548 encounters in 2008–2021) with diet data available (46 mixed-diet individuals feeding on both fish and mammals, and 411 exclusive fish-eaters) to quantify patterns of association within and between diet groups, and to identify underlying correlates. We genotyped a subset of 106 whales to assess patterns of genetic differentiation. Our results suggested kinship as main driver of social bonds within and among cohesive social units, while diet was most likely a consequence reflective of cultural diffusion, rather than a driver. Flexible associations within and between ecologically diverse social units led to a highly connected network, reducing social and genetic differentiation between diet groups. Our study points to a role of social connectivity, in combination with individual behavioural variation, in influencing population ecology in killer whales.
... Killer whales also have a wide variety of hunting traditions. In Argentina and on the Crozet Islands, they intentionally strand on the shore to catch young pinnipeds (Lopez, J. and Lopez, D., 1985;Guinet and Bouvier, 1995). In Antarctica, a group of killer whales dive synchronously to create a wave that washes a seal off an ice floe (Pitman and Durban, 2012). ...
Ecological niche partitioning is a process that allows organisms to achieve differences in resource use to reduce competition. Niche partitioning is traditionally viewed as a result of modification of genetically inherited traits through the process of adaptive evolution. However, in social animals with developed cognitive abilities, a significant portion of behavioral patterns is transmitted not genetically, but through social learning. Complex sets of behavioral patterns transmitted through social learning are called cultural traditions. The partitioning of ecological niches in cetaceans is most often considered in the context of morphological adaptations: changes in size, skull shape, and the structure of the filtering apparatus. The role of cultural traditions in niche partitioning is still poorly understood, but it is an important and promising area of research, as it provides a novel approach to the ability of animals to change their behavior in order to exploit the environment more efficiently. The main advantage of traditions over genetically inherited behavioral patterns is the ability to change quickly and spread rapidly in a population. Estimating the role of cultural traditions in ecological niche partitioning would highlight the significance of behavior plasticity and social learning in the evolution of animal intelligence. Ecological niche partitioning through the rapidly changing and rapidly spreading behavioral adaptations in the population, allowing to adapt quickly to changes in the environment, could provide a significant evolutionary advantage, which could lead to the development of a relatively high level of intelligence in cetaceans.
... Killer whales also have a wide variety of hunting traditions. In Argentina and on the Crozet Islands, they intentionally strand on the shore to catch young pinnipeds (Lopez, J. and Lopez, D., 1985;Guinet and Bouvier, 1995). In Antarctica, a group of killer whales dive synchronously to create a wave that washes a seal off an ice floe (Pitman and Durban, 2012). ...
... Finally, the question of which individual cats predate chicks arises, both in a fundamental perspective and for designing relevant management plans (see below and Appendix S3). Genetic samples of cats preying upon chicks would allow to test previous suggestions of heritability of this behavior (Barbraud et al., 2021), as shown in some predator species (Estes et al., 2003;Guinet & Bouvier, 1995) including cats (Bradshaw, 1992). Recent advances, such as DNA analysis of samples taken T A B L E 3 Possible management options in the context of the feral cat-albatross system in Kerguelen (see Appendix S3 for further details). ...
Invasive alien species are a major threat to seabird species, and the number of impacted species is still increasing. A recent study revealed for the first time that feral cats predated a large albatross species and that without cat control, some albatross populations would markedly decline. We examined this new predator–prey system by individually monitoring known‐age wandering albatross chicks with camera traps in a colony experimentally divided into zones with and without cat control. Our design allowed us to investigate how cat control influenced cat abundance and how this in turn influenced the probability for a chick to be predated by a cat. After cat controls, cat abundance was lower in controlled zones than in uncontrolled zones, while a survival analysis showed that the probability for a chick to die from cat predation depended on the zone but not on cat abundance. Our monitoring also provided a fine‐scale investigation of the various sources of chick mortality. In addition to cat predation (24% of mortality overall), our data documented predation by giant petrels, for the first time in Kerguelen, and revealed a strong and unexpected effect of nest flooding on chick mortality. Overall, our results underline the need for future studies investigating interindividual variability in cat diet and spatial ecology.
... In addition, horizontal and individual learning also plays a vital role in the development of their foraging skills (Simões-Lopes et al. 2016). Social learning plays an important role in the evolution of complex and cultural behaviors-e.g., "sponge tool use" and "beach hunting" in cetaceans (Guinet and Bouvier 1995;Patterson et al. 2015) and "tool use" in primates (Whiten et al. 1999). The longterm interaction between dolphins and fishers in the Tramandaí Inlet would probably not be possible without the learning process (Cram et al. 2022). ...
Many human cultures involve positive interactions with wildlife in the past and present. Lahille’s bottlenose dolphins (Tursiops gephyreus), for example, have developed tactics for coastal and estuarine foraging, which sustains a fishing practice known as “cooperative fishing” by traditional fishers in estuaries of southern Brazil. Here, we use aerial footage to describe the behavioral repertoire of the Lahille’s bottlenose dolphins and how it relates to the frequency of net casting by fishers in the Tramandaí Inlet. From nearly 8 h of footage from June 2017 to May 2018, we mainly observed dolphins foraging in the estuary inlet when fishers were present along the shoreline. Dolphins performed at least 27 clearly distinct behaviors and three types of movement patterns. A generalized additive model supported that the fishers interpret a subset of this repertoire (64%) as cues for casting their nets. The behavioral overview of the Lahille’s bottlenose dolphins presented here demonstrates not only a diverse repertoire for this population, but also its clear influence on fishers’ activities. Scientific and traditional perspectives should be integrated to better understand the ecological significance of this “cooperative fishing” for both dolphin populations and fishers that depend on them.
Significance statement
Interactions between different species can be very complex. It is a three-dimensional universe that comprises the behavioral and ecological characteristics of both sides, and then the dynamic they create together. In the case of the “cooperative fishing” between fishers and dolphins in southern Brazil, we still have one dimension to disclose in detail: the dolphins’ behavioral repertoire. Using aerial videos from a drone, we were able to shed light on how those dolphins behave and also how fishers coordinate their activity in response to the dolphins. We also showed that the dolphins’ behavioral repertoire is more diverse than assumed so far. Results suggest that the “cooperative fishing” seems to be based on the human’s perception of an extensive Lahille’s bottlenose dolphin behavioral repertoire during hunting. The knowledge provided here is essential to track the dynamic of this unique interaction in a given space and time.
For air-breathing marine predators that must save energy during dives, the ability to adopt hunting tactics that minimise the risk of triggering an escape reaction from the prey is crucial for efficient foraging. Female southern elephant seals (SES) Mirounga leonina forage on small mesopelagic prey that they must hunt almost continuously to meet their high-energy requirements. Here we aimed at understanding how these large time-limited deep-divers can efficiently exploit their small-sized prey. To do so, we used data recorded by a new biologger, the sonar tag, deployed on SES during their post-breeding foraging trips. This tag combines an active acoustic sensor with ultra-high-resolution movement and bioluminescence sensors. This combination of sensors offers a unique opportunity to simultaneously describe SES hunting tactics and defence mechanisms of their prey. We analysed more than 5800 prey capture events in 9 SES and show that they adopt a ‘stalking’ hunting behaviour, allowing them to get as close as possible to their prey before attacking. The ability of SES to adopt stealth approach tactics, minimising the risk of initiating a flight reaction from their prey, might be a key factor in the success of this far-ranging generalist predator.
Killer whales (Orcinus orca) feeding on herring (Clupea harengus) were observed both from the surface and underwater. We refer to one of the feeding techniques used by killer whales as the carousel method, whereby whales cooperatively herded herring into a tight ball close to the surface. During herding and feeding, whales swam around and under a school of herring, performing much lobtailing and porpoising. When the herring were gathered into a tight ball whales often swam with the white underside of their body towards the fish and emitted large bubbles close to the surface. While feeding, whales spent more time circling around the ball of fish than eating. Ball formation is a known defence mechanism used by schooling fish, and the effort by killer whales appeared to be directed towards keeping the ball very dense and close to the surface. The whales stunned their prey by slapping the edge of the school with the underside of their flukes and then ate the stunned fish one by one. The tail slaps created a loud banging sound which could have been either a by-product or an aid to stunning the prey.
Killer whales around Crozet Islands consume a great variety of preys, including fish, penguins (Eudyptes sp.), elephant seals (Mirounga leonina), and, occasionally, large cetacea. Prédation techniques used on elephant seals and penguins, which are easily observed from the shore, are described. Hydrophones were used to record the acoustic behaviour of the whales during their hunts for both types of prey. The successful predation of 29 elephant seals was observed, 24 of which were weaned pups. Seals were captured along the banks (n = 3), near river outlets (n = 14), by voluntary stranding of the whales on the beaches (n = 7), or by attack of seals swimming in bays (n = 5). Hunting techniques were routinely used in "strategic" points apparently chosen specifically according to the location and climatic factors. King penguins were hunted along the banks (n = 13), particularly where algae prevailed, or offshore (n = 32). While hunting, whales tended to be very quiet and used acoustic signals sparingly, emitting a few isolated clicks and short distance contact calls. Reactions of whales exposed to artificial sounds tended to show that they localize their prey by passive listening. When an elephant seal was captured, long distance contact calls characterized by excitement were emitted 72% of the time and resulted in the arrival, by "porpoising," of the most distant members of the group, along with whales of other groups coming from several kilometers away. The author hypothesizes that the adaptive value of this behaviour is to allow the size of the hunting unit to adjust itself to the size of the prey by permitting not only members of the same groupu to associate, but also members of other groups to associate temporarily.[Journal translation]
Over three hunting seasons, killer whales (Orcinus orca) from two pods were observed stranding intentionally on the beaches of Possession Island, Crozet Archipelago. Intentional stranding was performed principally by adult females to catch elephant seals on shore and during social play. Within a pod significant differences existed in the number of intentional strandings performed by individual females during hunting and also during "social beaching play." During intentional stranding, calves were associated with an adult female. Two calves were systematically associated with their mother, but one calf was associated significantly more with the two other pod females. This calf s mother stranded intentionally significantly less than the two other females. This suggests that alloparental "teaching" may occur within a pod according to the specific skills of the pod members.
Killer whales (Orcinus orca) were studied for three consecutive years in the Crozet Archipelago, Southern Indian Ocean, and 76 individual whales belonging to 18 pods were photo-identified.
At Crozet a pod is typically composed of a single matriarchal unit. The population was made up of 21 % adult males, 34 % adult females, and 45 % juveniles, and was declining at a 4 % annual rate. This unusually high rate of decrease may be explained by the strong reduction of the Elephant seal (Mirounga leonina) population that took place over the last 25 years in the Crozet Archipelago.
A comparison with the data available for other localities suggests that the average pod size of killer whales is dependent on the kind of prey they more generally hunt. Our observations also indicate that, within a population, pods may temporarily associate in a way to adjust their pod size to the body size of the prey. Such a behaviour appears to be unique among mammalian predators.
Using data from between 1973-4 and 1987, females have a mean life expectancy of 50.2 yr, typically give birth to their first viable calf at 14.9 yr of age, produce an average of 5.35 viable calves over a 25.2 yr reproductive lifespan and have a maximum longevity of c80-90 yr. Calving is diffusely seasonal with most births occurring in October-March. Neonate mortality is c43%. Proportion of mature females pregnant varies from 0.274 in April to 0.411 in September. Males have a mean life expectancy of 29.2 yr, typically attain sexual maturity at 15.0 yr and physical maturity at 21.0 yr of age, and have a maximum longevity of 50-60 yr. The derived life history parameters are used to develop a sex- and age-specific matrix population model and to calculate life tables. -from Authors
The prolonged nursing period of odontocetes relative to that of mysticetes is attributed to more sophisticated navigational training, kin-cooperation and complex social structure.
The paper describes the occurrence of Killer whales at Marion Island (Prince Edward group) in the south Indian Ocean from August 1973 to November 1976. They occur seasonally, being most numerous from October to December. Their occurrence is synchronized with the seasonal haul out of Southern elephant seals, but the seasonality of King, Rockhopper and Macaroni penguins is also likely to influence their occurrence. The largest herds occur in October, the month during which mean group size is also largest. Sex and age composition are given, adult males being significantly more numerous than adult females, while 36–3 % of the latter had calves. Hunting activity appears to be greatest between 15.00 and 17.00 hrs, and most Killer whales were seen within 100 m of the shore. Aspects of hunting, attacking, feeding and resting behaviour are discussed. The body measurements of a young male found on a beach are given.