Publications by authors named "John Durban"

Despite strong interest in how noise affects marine mammals, little is known for the most abundant and commonly exposed taxa. Social delphinids occur in groups of hundreds of individuals that travel quickly, change behaviour ephemerally and are not amenable to conventional tagging methods, posing challenges in quantifying noise impacts. We integrated drone-based photogrammetry, strategically placed acoustic recorders and broad-scale visual observations to provide complementary measurements of different aspects of behaviour for short- and long-beaked common dolphins.

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  • * The study specifically focuses on two ecotypes in the eastern North Pacific: the resident and Bigg's (transient) killer whales, assessing their ecological roles, physical traits, and genetic data.
  • * Findings support classifying both ecotypes as separate species, suggesting that Bigg's killer whales and resident killer whales should receive distinct taxonomic recognition.
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Body size is key to many life-history processes, including reproduction. Across species, climate change and other stressors have caused reductions in the body size to which animals can grow, called asymptotic size, with consequences for demography. A reduction in mean asymptotic length was documented for critically endangered North Atlantic right whales, in parallel with declines in health and vital rates resulting from human activities and environmental changes.

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  • Researchers are exploring how baleen whales locate dense prey in the ocean, focusing on their olfactory systems and potential for stereo-olfaction.
  • The study found a significant negative correlation between the width of whale nares and their trophic levels, indicating that whales adapted for better smell are more likely to eat zooplankton.
  • The findings suggest that certain baleen whale species may be able to detect odorants like dimethyl sulfide (DMS), which raises concerns about their potential for ingesting plastic through DMS detection.
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  • Climate change is causing rapid transformations in polar ecosystems, impacting various species, particularly at lower trophic levels.
  • Long-lived and mobile species like gray whales might cope better with short-term changes, but their survival still depends on the availability of prey in warming Arctic conditions.
  • Significant mortality events in gray whales, linked to low prey biomass and high ice cover, indicate that even adaptable species are vulnerable to the changing Arctic environment.
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Anthropogenic activities can lead to changes in animal behavior. Predicting population consequences of these behavioral changes requires integrating short-term individual responses into models that forecast population dynamics across multiple generations. This is especially challenging for long-lived animals, because of the different time scales involved.

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  • Whales, despite being massive, are active predators that need to be agile to capture smaller prey, leading to the development of unique movement strategies that require significant energy and mechanical power.
  • Research on seven baleen whale species shows that as whale size increases, their maneuvering performance, such as acceleration and agility, decreases, meaning larger whales are generally less agile than smaller ones.
  • However, larger whales adapt their behaviors to cope with their size, employing maneuvers that enhance their capability, indicating that they have evolved specific physical traits to optimize their movement despite their bulk.
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Assessing the patterns of wildlife attendance to specific areas is relevant across many fundamental and applied ecological studies, particularly when animals are at risk of being exposed to stressors within or outside the boundaries of those areas. Marine mammals are increasingly being exposed to human activities that may cause behavioral and physiological changes, including military exercises using active sonars. Assessment of the population-level consequences of anthropogenic disturbance requires robust and efficient tools to quantify the levels of aggregate exposure for individuals in a population over biologically relevant time frames.

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Runs of homozygosity (ROH) occur when offspring inherit haplotypes that are identical by descent from each parent. Length distributions of ROH are informative about population history; specifically, the probability of inbreeding mediated by mating system and/or population demography. Here, we investigated whether variation in killer whale (Orcinus orca) demographic history is reflected in genome-wide heterozygosity and ROH length distributions, using a global data set of 26 genomes representative of geographic and ecotypic variation in this species, and two F1 admixed individuals with Pacific-Atlantic parentage.

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Whales are now largely protected from direct harvest, leading to partial recoveries in many previously depleted species. However, most populations remain far below their historical abundances and incidental human impacts, especially vessel strikes and entanglement in fishing gear, are increasingly recognized as key threats. In addition, climate-driven changes to prey dynamics are impacting the seasonal foraging grounds of many baleen whales.

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Whaling has decimated North Atlantic right whales Eubalaena glacialis (NARW) since the 11th century and southern right whales E. australis (SRW) since the 19th century. Today, NARWs are Critically Endangered and decreasing, whereas SRWs are recovering.

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Killer whales () are top marine predators occurring globally. In Antarctic waters, five ecotypes have been described, with Type C being the smallest form of killer whale known. Acoustic recordings of nine encounters of Type C killer whales were collected in 2012 and 2013 in McMurdo Sound, Ross Sea.

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  • During the gray whale migration from late 2014 to early 2015, researchers used acoustic calls, infrared technology, and visual sightings to estimate whale populations.
  • The average gray whale call rate was about 7.5 calls per whale per day, peaking during the migration, allowing for the estimate of 4,340 whales migrating south before visual observations began.
  • To improve future studies, it's suggested to increase survey efforts throughout December and utilize multiple infrared cameras tailored for various distances offshore, as detection rates varied significantly by location.
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Reconstruction of the demographic and evolutionary history of populations assuming a consensus tree-like relationship can mask more complex scenarios, which are prevalent in nature. An emerging genomic toolset, which has been most comprehensively harnessed in the reconstruction of human evolutionary history, enables molecular ecologists to elucidate complex population histories. Killer whales have limited extrinsic barriers to dispersal and have radiated globally, and are therefore a good candidate model for the application of such tools.

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  • Recent research highlights the relationship between hosts, like killer whales, and their skin microbiota, linking microbial profiles to the host's biology and health.
  • By analyzing shotgun sequencing data from killer whale skin biopsies, scientists identified 845 microbial taxa and discovered that both ecological types and geography impact the composition of their skin microbiomes.
  • The study reveals key microbial communities, notes the influence of diatom presence on skin condition, and suggests how the movement of killer whales affects the presence of potentially harmful bacteria, showcasing the value of metagenomics for understanding host-microbe interactions.
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  • The study investigates the respiratory microbiome of healthy humpback whales using unmanned hexacopters to collect their exhaled breath from two different locations: Massachusetts and Vancouver Island.
  • Results reveal a distinct core microbiome, consisting of 25 specific bacteria that are consistently found among the sampled whales and may indicate a healthy pulmonary system.
  • Pathogen screening showed no known respiratory pathogens in the blow samples, highlighting the potential of using noninvasive methods for health monitoring in cetacean populations.
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Dive capacity among toothed whales (suborder: Odontoceti) has been shown to generally increase with body mass in a relationship closely linked to the allometric scaling of metabolic rates. However, two odontocete species tagged in this study, the Blainville's beaked whale Mesoplodon densirostris and the Cuvier's beaked whale Ziphius cavirostris, confounded expectations of a simple allometric relationship, with exceptionally long (mean: 46.1 min & 65.

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  • The study analyzes population genomic data from killer whale ecotypes, finding that genetic differences are linked to their socially inherited ecological niches, which have developed in less than 250,000 years.
  • It identifies historical bottlenecks during the founding of populations, leading to ecological divergence and genetic drift, resulting in noticeable genomic differences between separate (allopatric) and overlapping (sympatric) ecotypes.
  • The research highlights the role of social learning and behavioral responses in ecological adaptation and evolution, emphasizing the interplay between demographics, culture, and genetics.
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Global climate change during the Late Pleistocene periodically encroached and then released habitat during the glacial cycles, causing range expansions and contractions in some species. These dynamics have played a major role in geographic radiations, diversification and speciation. We investigate these dynamics in the most widely distributed of marine mammals, the killer whale (Orcinus orca), using a global data set of over 450 samples.

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The difficulties associated with detecting population boundaries have long constrained the conservation and management of highly mobile, wide-ranging marine species, such as killer whales (Orcinus orca). In this study, we use data from 26 nuclear microsatellite loci and mitochondrial DNA sequences (988bp) to test a priori hypotheses about population subdivisions generated from a decade of killer whale surveys across the northern North Pacific. A total of 462 remote skin biopsies were collected from wild killer whales primarily between 2001 and 2010 from the northern Gulf of Alaska to the Sea of Okhotsk, representing both the piscivorous "resident" and the mammal-eating "transient" (or Bigg's) killer whales.

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Killer whales (Orcinus orca) are the most widely distributed marine mammals and have radiated to occupy a range of ecological niches. Disparate sympatric types are found in the North Atlantic, Antarctic and North Pacific oceans, however, little is known about the underlying mechanisms driving divergence. Previous phylogeographic analysis using complete mitogenomes yielded a bifurcating tree of clades corresponding to described ecotypes.

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Beaked whales have mass stranded during some naval sonar exercises, but the cause is unknown. They are difficult to sight but can reliably be detected by listening for echolocation clicks produced during deep foraging dives. Listening for these clicks, we documented Blainville's beaked whales, Mesoplodon densirostris, in a naval underwater range where sonars are in regular use near Andros Island, Bahamas.

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Facial and vocal expressions of emotion have been found in a number of social mammal species and are thought to have evolved to aid social communication. There has been much debate about whether such signals are culturally inherited or are truly biologically innate. Evidence for the innateness of such signals can come from cross-cultural studies.

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Mitochondria produce up to 95 per cent of the eukaryotic cell's energy. The coding genes of the mitochondrial DNA may therefore evolve under selection owing to metabolic requirements. The killer whale, Orcinus orca, is polymorphic, has a global distribution and occupies a range of ecological niches.

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Killer whales (Orcinus orca) currently comprise a single, cosmopolitan species with a diverse diet. However, studies over the last 30 yr have revealed populations of sympatric "ecotypes" with discrete prey preferences, morphology, and behaviors. Although these ecotypes avoid social interactions and are not known to interbreed, genetic studies to date have found extremely low levels of diversity in the mitochondrial control region, and few clear phylogeographic patterns worldwide.

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