scholarly journals Linking killer whale survival and prey abundance: food limitation in the oceans' apex predator?

2009 ◽  
Vol 6 (1) ◽  
pp. 139-142 ◽  
Author(s):  
John K. B. Ford ◽  
Graeme M. Ellis ◽  
Peter F. Olesiuk ◽  
Kenneth C. Balcomb
Keyword(s):  
Prey Species ◽  
Killer Whale ◽  
Prey Availability ◽  
Trophic Position ◽  
Marine Ecosystem ◽  
Food Limitation ◽  
Ecosystem Dynamics ◽  
Foraging Strategies ◽  
Limiting Factor ◽  
Killer Whales

Killer whales ( Orcinus orca ) are large predators that occupy the top trophic position in the world's oceans and as such may have important roles in marine ecosystem dynamics. Although the possible top-down effects of killer whale predation on populations of their prey have received much recent attention, little is known of how the abundance of these predators may be limited by bottom-up processes. Here we show, using 25 years of demographic data from two populations of fish-eating killer whales in the northeastern Pacific Ocean, that population trends are driven largely by changes in survival, and that survival rates are strongly correlated with the availability of their principal prey species, Chinook salmon ( Oncorhynchus tshawytscha ). Our results suggest that, although these killer whales may consume a variety of fish species, they are highly specialized and dependent on this single salmonid species to an extent that it is a limiting factor in their population dynamics. Other ecologically specialized killer whale populations may be similarly constrained to a narrow range of prey species by culturally inherited foraging strategies, and thus are limited in their ability to adapt rapidly to changing prey availability.

scholarly journals Passive acoustic monitoring of killer whales (Orcinus orca) reveals year-round distribution and residency patterns in the Gulf of Alaska

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hannah J. Myers ◽  
Daniel W. Olsen ◽  
Craig O. Matkin ◽  
Lara A. Horstmann ◽  
Brenda Konar
Keyword(s):  
Killer Whale ◽  
Marine Ecosystem ◽  
Distribution Patterns ◽  
Gulf Of Alaska ◽  
Acoustic Monitoring ◽  
Orcinus Orca ◽  
Killer Whales ◽  
Passive Acoustic Monitoring ◽  
The North ◽  
Passive Acoustic

AbstractKiller whales (Orcinus orca) are top predators throughout the world’s oceans. In the North Pacific, the species is divided into three ecotypes—resident (fish-eating), transient (mammal-eating), and offshore (largely shark-eating)—that are genetically and acoustically distinct and have unique roles in the marine ecosystem. In this study, we examined the year-round distribution of killer whales in the northern Gulf of Alaska from 2016 to 2020 using passive acoustic monitoring. We further described the daily acoustic residency patterns of three killer whale populations (southern Alaska residents, Gulf of Alaska transients, and AT1 transients) for one year of these data. Highest year-round acoustic presence occurred in Montague Strait, with strong seasonal patterns in Hinchinbrook Entrance and Resurrection Bay. Daily acoustic residency times for the southern Alaska residents paralleled seasonal distribution patterns. The majority of Gulf of Alaska transient detections occurred in Hinchinbrook Entrance in spring. The depleted AT1 transient killer whale population was most often identified in Montague Strait. Passive acoustic monitoring revealed that both resident and transient killer whales used these areas much more extensively than previously known and provided novel insights into high use locations and times for each population. These results may be driven by seasonal foraging opportunities and social factors and have management implications for this species.

scholarly journals Survival of the fattest: linking body condition to prey availability and survivorship of killer whales

Ecosphere ◽  
2021 ◽  
Vol 12 (8) ◽  
Author(s):  
Joshua D. Stewart ◽  
John W. Durban ◽  
Holly Fearnbach ◽  
Lance G. Barrett‐Lennard ◽  
Paige K. Casler ◽  
...  
Keyword(s):  
Body Condition ◽  
Prey Availability ◽  
Killer Whales

scholarly journals Family feud: permanent group splitting in a highly philopatric mammal, the killer whale (Orcinus orca)

2021 ◽  
Vol 75 (3) ◽  
Author(s):  
Eva H. Stredulinsky ◽  
Chris T. Darimont ◽  
Lance Barrett-Lennard ◽  
Graeme M. Ellis ◽  
John K. B. Ford
Keyword(s):  
Killer Whale ◽  
Group Structure ◽  
Group Living ◽  
Orcinus Orca ◽  
Learning Approaches ◽  
Killer Whales ◽  
Internal Factors ◽  
Individual Fitness ◽  
Leadership Experience

Abstract For animals that tend to remain with their natal group rather than individually disperse, group sizes may become too large to benefit individual fitness. In such cases, group splitting (or fission) allows philopatric animals to form more optimal group sizes without sacrificing all familiar social relationships. Although permanent group splitting is observed in many mammals, it occurs relatively infrequently. Here, we use combined generalized modeling and machine learning approaches to provide a comprehensive examination of group splitting in a population of killer whales (Orcinus orca) that occurred over three decades. Fission occurred both along and across maternal lines, where animals dispersed in parallel with their closest maternal kin. Group splitting was more common: (1) in larger natal groups, (2) when the common maternal ancestor was no longer alive, and (3) among groups with greater substructuring. The death of a matriarch did not appear to immediately trigger splitting. Our data suggest intragroup competition for food, leadership experience and kinship are important factors that influence group splitting in this population. Our approach provides a foundation for future studies to examine the dynamics and consequences of matrilineal fission in killer whales and other taxa. Significance statement Group living among mammals often involves long-term social affiliation, strengthened by kinship and cooperative behaviours. As such, changes in group membership may have significant consequences for individuals’ fitness and a population’s genetic structure. Permanent group splitting is a complex and relatively rare phenomenon that has yet to be examined in detail in killer whales. In the context of a growing population, in which offspring of both sexes remain with their mothers for life, we provide the first in-depth examination of group splitting in killer whales, where splitting occurs both along and across maternal lines. We also undertake the first comprehensive assessment of how killer whale intragroup cohesion is influenced by both external and internal factors, including group structure, population and group demography, and resource abundance.

Coupling stable isotopes with bioenergetics to evaluate sources of variation in organochlorine concentrations in Baltic salmon (Salmo salar)

2008 ◽  
Vol 65 (10) ◽  
pp. 2114-2126 ◽  
Author(s):  
Mikko Kiljunen ◽  
Heikki Peltonen ◽  
Roger I. Jones ◽  
Hannu Kiviranta ◽  
Pekka J. Vuorinen ◽  
...  
Keyword(s):  
Salmo Salar ◽  
Individual Variation ◽  
Prey Species ◽  
Trophic Position ◽  
Gulf Of Finland ◽  
Cercopagis Pengoi ◽  
Dioxins And Furans ◽  
Predatory Cladoceran ◽  
Sources Of Variation ◽  
The Gulf Of Finland

Atlantic salmon ( Salmo salar ) collected from three locations around the northern Baltic Sea in 2003–2004 showed large spatial and individual variation in their organochlorines (OCs) (polychlorinated dibenzo-p-dioxins and furans and polychlorinated biphenyls). This variation could be explained only partly by their size or sea age. The variability arose from the differences in salmon diet, trophic position, and prey OC concentrations and lipid content. A salmon bioenergetics accumulation model was used to evaluate the contribution of salmon growth and their diet to the observed individual variation in OC content. Our model revealed that the contribution of three main prey species in the OC accumulation of salmon varied markedly between the study areas. Amount of lipids in salmon explained a large proportion of their OC concentration. However, trophic position of salmon calculated from the δ15N values explained almost 80% of the variation in lipid-normalized OC concentrations. In the Gulf of Finland, where OC concentrations of salmon were highest, their prey species had the highest OC concentrations and trophic positions. Higher OC concentrations in the Gulf of Finland might be related to elevated trophic positions caused by invasion of the predatory cladoceran Cercopagis pengoi in 1990.

Development of intentional stranding hunting techniques in killer whale (Orcinus orca) calves at Crozet Archipelago

1995 ◽  
Vol 73 (1) ◽  
pp. 27-33 ◽  
Author(s):  
Christophe Guinet ◽  
Jérome Bouvier
Keyword(s):  
Growth Curve ◽  
Parental Investment ◽  
Killer Whale ◽  
Elephant Seal ◽  
Orcinus Orca ◽  
Killer Whales ◽  
Juvenile Female ◽  
Adult Females ◽  
Social Transfer ◽  
High Degree

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.

scholarly journals A long post-reproductive lifespan is a shared trait among genetically distinct killer whale populations

2021 ◽  
Author(s):  
Mia Nielsen ◽  
Samuel Ellis ◽  
Jared Towers ◽  
Thomas Doniol-Valcroze ◽  
Daniel Franks ◽  
...  
Keyword(s):  
Social Structure ◽  
Killer Whale ◽  
Demographic Data ◽  
Reproductive Period ◽  
Substantial Variation ◽  
Killer Whales ◽  
Reproductive Conflict ◽  
Demographic Patterns ◽  
General Prediction

The extended female post-reproductive lifespan 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 post-reproductive lifespan due to the combined costs of inter-generational 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 post-reproductive lifespan in both ecotypes with >30% of adult female years being lived as post-reproductive, supporting the general prediction that an increase in local relatedness with age predisposes the evolution of a post-reproductive lifespan. Differences in the magnitude of kinship dynamics however, did not influence the timing or duration of the post-reproductive lifespan with females in both ecotypes terminating reproduction before their mid-40s followed by an expected post-reproductive period of ~20 years. Our results highlight the important role of kinship dynamics in the evolution of a long post-reproductive lifespan 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 population.

scholarly journals Making inference from wildlife collision data: inferring predator absence from prey strikes

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3014 ◽  
Author(s):  
Peter Caley ◽  
Geoffrey R. Hosack ◽  
Simon C. Barry
Keyword(s):  
Prey Species ◽  
Red Fox ◽  
Prey Availability ◽  
Numerical Response ◽  
Practical Application ◽  
Ecological Inference ◽  
Predator Species ◽  
New Approach ◽  
Predictive Probability ◽  
Irreducible Uncertainty

Wildlife collision data are ubiquitous, though challenging for making ecological inference due to typically irreducible uncertainty relating to the sampling process. We illustrate a new approach that is useful for generating inference from predator data arising from wildlife collisions. By simply conditioning on a second prey species sampled via the same collision process, and by using a biologically realistic numerical response functions, we can produce a coherent numerical response relationship between predator and prey. This relationship can then be used to make inference on the population size of the predator species, including the probability of extinction. The statistical conditioning enables us to account for unmeasured variation in factors influencing the runway strike incidence for individual airports and to enable valid comparisons. A practical application of the approach for testing hypotheses about the distribution and abundance of a predator species is illustrated using the hypothesized red fox incursion into Tasmania, Australia. We estimate that conditional on the numerical response between fox and lagomorph runway strikes on mainland Australia, the predictive probability of observing no runway strikes of foxes in Tasmania after observing 15 lagomorph strikes is 0.001. We conclude there is enough evidence to safely reject the null hypothesis that there is a widespread red fox population in Tasmania at a population density consistent with prey availability. The method is novel and has potential wider application.

scholarly journals Gut content analysis of cattle egrets (Bubulcus ibis) in Asam Kumbang Crocodile Park, North Sumatra

2021 ◽  
Vol 912 (1) ◽  
pp. 012105
Author(s):  
E Jumilawaty ◽  
N Namira ◽  
A Anggelicha ◽  
A Hartanto
Keyword(s):  
Content Analysis ◽  
Prey Species ◽  
Prey Availability ◽  
Biological Control Agent ◽  
Food Resource ◽  
Control Agent ◽  
Gut Content Analysis ◽  
Gut Content ◽  
Dominant Group ◽  
Bubulcus Ibis

Abstract Cattle egret (Bubulcus ibis) is a widespread avian species inhabiting a variety of natural and artificial sites. Asam Kumbang Crocodile Park is one of establishments that occupied some portions of B. ibis habitat with no recent information on the food resource and prey availability for the viability of B. ibis. To this aim, we collected 10 random individuals of B. ibis to be sacrificed for gut content analysis of prey species. A total of 19 taxa was found as prey items in the gut of B. ibis with the dominant group from insects (Orthoptera, Scolopendromorpha). The diversity of prey species was categorized as moderate with intraspecific diet variation which formed four guilds that fed on specific taxa namely Group 1 (Haplotaxida, Lepidoptera, Anurans), Group 2 (Blattodea, Coleoptera, Araneae), Group 3 (Orthoptera, Scolopendromorpha); and Group 4 (Dermaptera, Squamata). Oxya chinensis and Oxya velox are important rice grasshopper pests that were also found in the gut of B. ibis reflecting their potential function as biological control agent.

Sign in / Sign up

Export Citation Format

Share Document