The Experts below are selected from a list of 285 Experts worldwide ranked by ideXlab platform
Hal Whitehead - One of the best experts on this subject based on the ideXlab platform.
-
Long-term associations among male sperm whales (Physeter macrocephalus).
PloS one, 2020Co-Authors: Hayao Kobayashi, Hal Whitehead, Masao AmanoAbstract:Little is known about the social structure of male sperm whales (Physeter macrocephalus) after they leave their natal units. While previous studies found no evidence for preferred associations among males, the observation of mass-strandings consisting exclusively of males, suggest that they have strong social bonds. To investigate the social associations among male sperm whales, we used half weight index of association, permutation tests and standardized lagged association rate models on a large photo-identification database collected between 2006 and 2017 in Nemuro Strait, Japan. Our results suggest that while male sperm whales are not as social as females, they do form long term associations, have preferred companionship, and forage in social proximity to each other. The best-fitting model to the standardized lagged association rate showed that associations among males last for at least 2.7 years and as most males leave the area after 2 years, associations may last for longer. Twenty dyads were observed associating over more than 2 years, for a maximum 5 years. One dyad was observed associating on 19 different days and clustered on 7 different days. Male associations may function to enhance foraging or to fend off predators. Such relationships seem to be adapted to a pelagic habitat with uncertain resource availability and predation pressure.
-
habitat use of culturally distinct galapagos sperm whale Physeter macrocephalus clans
Marine Ecology Progress Series, 2019Co-Authors: Ana Eguiguren, Mauricio Cantor, Luke Rendell, Enrico Pirotta, Hal WhiteheadAbstract:Dalhousie University (Nova Scotia Graduate Scholarship; Patrick F. Lett Graduate Students’ Assistance Bursary); Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (202581/2011-0; 153797/2016-9); Scottish Funding Council (grant reference HR09011)
-
galapagos sperm whales Physeter macrocephalus waxing and waning over three decades
Canadian Journal of Zoology, 2017Co-Authors: Mauricio Cantor, Ana Eguiguren, Godfrey Merlen, Hal WhiteheadAbstract:While population sizes and structures naturally fluctuate over time, rapid within-generation changes are usually driven by habitat quality shifts and/or abrupt mortality. We evaluate how sperm whales ( Physeter macrocephalus , L. 1758 (= Physeter catodon , L. 1758)) responded to the dynamic habit off the Galapagos Islands over 30 years, relating it to variation in prey availability and whaling operations in the tropical Pacific. In the 1980’s, males and females were commonly sighted foraging and socializing in the northwest of the archipelago. Sightings decreased during the 1990’s; by the 2000’s they became very rare: occasional single foraging males were sighted and females abandoned the archipelago. In the 2010’s, whales return to the southern waters, in large groups with apparently more breeding males and calves. The waxing and waning of Galapagos sperm whales are likely caused by environmental shifts together with ripple effects of whaling. Their patchy prey are influenced by variation in se...
-
Galápagos sperm whales ( Physeter macrocephalus ): waxing and waning over three decades
Canadian Journal of Zoology, 2017Co-Authors: Mauricio Cantor, Ana Eguiguren, Godfrey Merlen, Hal WhiteheadAbstract:While population sizes and structures naturally fluctuate over time, rapid within-generation changes are usually driven by shifts in habitat quality and (or) abrupt mortality. We evaluate how sperm whales (Physeter macrocephalus L., 1758 = Physeter catodon L., 1758) responded to the dynamic habit off the Galápagos Islands over 30 years, relating it to variation in prey availability and whaling operations in the tropical Pacific. In the 1980s, males and females were commonly sighted foraging and socializing in the northwest of the archipelago. Sightings decreased during the 1990s; by the 2000s, they became very rare: occasional single foraging males were sighted and females abandoned the archipelago. In the 2010s, whales return to the southern waters, in large groups with apparently more breeding males and calves. The waxing and waning of Galápagos sperm whales are likely caused by environmental shifts together with ripple effects of whaling. Their patchy prey are influenced by variation in sea temperature and productivity, which drives movements of whales in and out of the archipelago. Whaling may have aggravated these movements by leaving an attractive surplus of prey in coastal waters depleted of whales. These findings highlight the magnitude of spatiotemporal scales used by sperm whales and the consequent challenges of assessing population dynamics of long-lived, mobile pelagic species.
-
can genetic differences explain vocal dialect variation in sperm whales Physeter macrocephalus
Behavior Genetics, 2012Co-Authors: Luke Rendell, Sarah L Mesnick, Merel L Dalebout, Jessica Burtenshaw, Hal WhiteheadAbstract:Sperm whale social groups can be assigned to vocal clans based on their production of codas, short stereotyped patterns of clicks. It is currently unclear whether genetic variation could account for these behavioural differences. We studied mitochondrial DNA (mtDNA) variation among sympatric vocal clans in the Pacific Ocean, using sequences extracted from sloughed skin samples. We sampled 194 individuals from 30 social groups belonging to one of three vocal clans. As in previous studies of sperm whales, mtDNA control region diversity was low (π = 0.003), with just 14 haplotypes present in our sample. Both hierarchical AMOVAs and partial Mantel tests showed that vocal clan was a more important factor in matrilineal population genetic structure than geography, even though our sampling spanned thousands of kilometres. The variance component attributed to vocal dialects (7.7%) was an order of magnitude higher than those previously reported in birds, while the variance component attributed to geographic area was negligible. Despite this, the two most common haplotypes were present in significant quantities in each clan, meaning that variation in the control region cannot account for behavioural variation between clans, and instead parallels the situation in humans where parent-offspring transmission of language variation has resulted in correlations with neutral genes. Our results also raise questions for the management of sperm whale populations, which has traditionally been based on dividing populations into geographic ‘stocks’, suggesting that culturally-defined vocal clans may be more appropriate management units.
Luke Rendell - One of the best experts on this subject based on the ideXlab platform.
-
habitat use of culturally distinct galapagos sperm whale Physeter macrocephalus clans
Marine Ecology Progress Series, 2019Co-Authors: Ana Eguiguren, Mauricio Cantor, Luke Rendell, Enrico Pirotta, Hal WhiteheadAbstract:Dalhousie University (Nova Scotia Graduate Scholarship; Patrick F. Lett Graduate Students’ Assistance Bursary); Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (202581/2011-0; 153797/2016-9); Scottish Funding Council (grant reference HR09011)
-
mediterranean sperm whales Physeter macrocephalus the precarious state of a lost tribe
Advances in Marine Biology, 2016Co-Authors: Luke Rendell, Alexandros FrantzisAbstract:First observed in the classical era, a population of sperm whales (Physeter macrocephalus) persists to this day in the deep waters of the Mediterranean Sea. Genetic and observational evidence support the notion that this is an isolated population, separated from its Atlantic neighbours. These whales depend on mesopelagic squid for food, and appear to occupy a very similar ecological niche to sperm whales in the open oceans. Recent evidence proving that individuals can pass between the eastern and western deep water basins confirms that this is a single population, not isolated into western and eastern stocks. We lack robust information on their population status, but they could number in the hundreds rather than thousands, and current densities appear to be much lower than those reported in the 1950s, suggesting that we should be very concerned about the conservation status of this population. This makes it vitally important to address the serious threats posed by ship strikes and entanglement in fishing nets, especially driftnets, and to carefully monitor other potential sources of anthropogenic impact. A step change in funding to collect better data and a clear shift in policy priorities are needed if we are to be serious about conserving this population.
-
can genetic differences explain vocal dialect variation in sperm whales Physeter macrocephalus
Behavior Genetics, 2012Co-Authors: Luke Rendell, Sarah L Mesnick, Merel L Dalebout, Jessica Burtenshaw, Hal WhiteheadAbstract:Sperm whale social groups can be assigned to vocal clans based on their production of codas, short stereotyped patterns of clicks. It is currently unclear whether genetic variation could account for these behavioural differences. We studied mitochondrial DNA (mtDNA) variation among sympatric vocal clans in the Pacific Ocean, using sequences extracted from sloughed skin samples. We sampled 194 individuals from 30 social groups belonging to one of three vocal clans. As in previous studies of sperm whales, mtDNA control region diversity was low (π = 0.003), with just 14 haplotypes present in our sample. Both hierarchical AMOVAs and partial Mantel tests showed that vocal clan was a more important factor in matrilineal population genetic structure than geography, even though our sampling spanned thousands of kilometres. The variance component attributed to vocal dialects (7.7%) was an order of magnitude higher than those previously reported in birds, while the variance component attributed to geographic area was negligible. Despite this, the two most common haplotypes were present in significant quantities in each clan, meaning that variation in the control region cannot account for behavioural variation between clans, and instead parallels the situation in humans where parent-offspring transmission of language variation has resulted in correlations with neutral genes. Our results also raise questions for the management of sperm whale populations, which has traditionally been based on dividing populations into geographic ‘stocks’, suggesting that culturally-defined vocal clans may be more appropriate management units.
-
individual vocal production in a sperm whale Physeter macrocephalus social unit
Marine Mammal Science, 2011Co-Authors: Tyler M Schulz, Hal Whitehead, Shane Gero, Luke RendellAbstract:The vocal repertoires of group-living animals may communicate individual or group identity. Female and juvenile sperm whales live in long-term social units that can be assigned to vocal clans based on the pattern of clicks in coda vocalizations. An unusual set of circumstances allowed us to record the vocalizations of photo-identified individuals within a single social unit over a 41 d period. Using click interpulse intervals, we were able to assign codas to individuals and investigate coda production at the individual level within a social unit for the first time. Adult females in the unit vocalized at approximately equal rates. A calf and juvenile, both male, vocalized less often than the adult females. Repertoires were indistinguishable for all unit members apart from a mother and her calf, which possessed significantly different repertoires—even from one another. We suggest that similarity among the coda repertoires of most unit members indicates a function in advertising unit identity. In contrast, the distinctive repertoires of the calf and its mother may facilitate reunions between these whales. We hypothesize that sperm whales may be able to vary their vocal repertoires as their reproductive status alters the trade-off between the benefits of individual and group identification.
-
Coda vocalizations recorded in breeding areas are almost entirely produced by mature female sperm whales (Physeter macrocephalus)
Canadian Journal of Zoology, 2006Co-Authors: Marianne Marcoux, Hal Whitehead, Luke RendellAbstract:We investigated the use and function of coda communication by sperm whales (Physeter macrocephalusL., 1758 (= Physeter catodon L., 1758)). Codas are stereotyped patterns of clicks often made by sperm whales in social con- texts. We used the pulsed structure of coda clicks recorded from socializing female/immature groups to estimate the body- length distribution of the animals producing the codas. Ninety-five percent of the 10 653 codas that we measured were pro- duced by whales measuring from 9 to 11 m. This size range corresponds to the lengths of mature females. We compared these data to a length distribution calculated from photographic measurements of individuals from the same groups en- countered during the same studies. There were more whales shorter than 8.5 m (10.0%) and longer than 12.5 m (2.7%) in the photographic length distribution than in that of the coda producers (0.30% and 0.08%, respectively). Since males leave their natal group when they are shorter than 9 m and return to breeding areas when they measure 13 m or more, our data show that the codas were produced almost entirely by mature females. We suggest that coda communication serves several functions, including social bonding.
Peter L. Tyack - One of the best experts on this subject based on the ideXlab platform.
-
deep diving foraging behaviour of sperm whales Physeter macrocephalus
Journal of Animal Ecology, 2006Co-Authors: Stephanie L Watwood, Patrick J. O. Miller, Peter T Madsen, Mark P Johnson, Peter L. TyackAbstract:1. Digital tags were used to describe diving and vocal behaviour of sperm whales during 198 complete and partial foraging dives made by 37 individual sperm whales in the Atlantic Ocean, the Gulf of Mexico and the Ligurian Sea. 2. The maximum depth of dive averaged by individual differed across the three regions and was 985 m (SD = 124.3), 644 m (123.4) and 827 m (60.3), respectively. An average dive cycle consisted of a 45 min (6.3) dive with a 9 min (3.0) surface interval, with no significant differences among regions. On average, whales spent greater than 72% of their time in foraging dive cycles. 3. Whales produced regular clicks for 81% (4.1) of a dive and 64% (14.6) of the descent phase. The occurrence of buzz vocalizations (also called 'creaks') as an indicator of the foraging phase of a dive showed no difference in mean prey capture attempts per dive between regions [18 buzzes/dive (7.6)]. Sperm whales descended a mean of 392 m (144) from the start of regular clicking to the first buzz, which supports the hypothesis that regular clicks function as a long-range biosonar. 4. There were no significant differences in the duration of the foraging phase [28 min (6.0)] or percentage of the dive duration in the foraging phase [62% (7.3)] between the three regions, with an overall average proportion of time spent actively encountering prey during dive cycles of 0.53 (0.05). Whales maintained their time in the foraging phase by decreasing transit time for deeper foraging dives. 5. Similarity in foraging behaviour in the three regions and high diving efficiencies suggest that the success of sperm whales as mesopelagic predators is due in part to long-range echolocation of deep prey patches, efficient locomotion and a large aerobic capacity during diving.
-
swimming gaits passive drag and buoyancy of diving sperm whales Physeter macrocephalus
The Journal of Experimental Biology, 2004Co-Authors: Patrick J. O. Miller, Peter L. Tyack, Mark P Johnson, Eugene A TerrayAbstract:SUMMARY Drag and buoyancy are two primary external forces acting on diving marine mammals. The strength of these forces modulates the energetic cost of movement and may influence swimming style (gait). Here we use a high-resolution digital tag to record depth, 3-D orientation, and sounds heard and produced by 23 deep-diving sperm whales in the Ligurian Sea and Gulf of Mexico. Periods of active thrusting versus gliding were identified through analysis of oscillations measured by a 3-axis accelerometer. Accelerations during 382 ascent glides of five whales (which made two or more steep ascents and for which we obtained a measurement of length) were strongly affected by depth and speed at Reynold9s numbers of 1.4–2.8×107. The accelerations fit a model of drag, air buoyancy and tissue buoyancy forces with an r2 of 99.1–99.8% for each whale. The model provided estimates (mean ± s.d.) of the drag coefficient (0.00306±0.00015), air carried from the surface (26.4±3.9 l kg-3 mass), and tissue density (1030±0.8 kg m-3) of these five animals. The model predicts strong positive buoyancy forces in the top 100 m of the water column, decreasing to near neutral buoyancy at 250–850 m. Mean descent speeds (1.45±0.19 m s-1) were slower than ascent speeds (1.63±0.22 m s-1), even though sperm whales stroked steadily (glides 5.3±6.3%) throughout descents and employed predominantly stroke-and-glide swimming (glides 37.7±16.4%) during ascents. Whales glided more during portions of dives when buoyancy aided their movement, and whales that glided more during ascent glided less during descent (and vice versa), supporting the hypothesis that buoyancy influences behavioural swimming decisions. One whale rested at∼ 10 m depth for more than 10 min without fluking, regulating its buoyancy by releasing air bubbles.
-
Pattern similarity in shared codas from sperm whales (Physeter catodon)
Marine Mammal Science, 1993Co-Authors: Karen E. Moore, William A. Watkins, Peter L. TyackAbstract:: Codas (patterned click sequences) produced by sperm whales (Physeter catodon) were recorded during four research cruises in the southeast Caribbean. Two coda patterns comprised more than 50% of the codas analyzed from 46 h of recording. These two patterns were called “shared” codas because they were produced by numerous whales throughout the area, both as repeated sequences by individual whales, at times simultaneously by two or more whales, and occasionally in overlapping series. Analyses of both the absolute timing and the relative timing of click intervals indicate equivalent variability in the temporal patterns of similar shared codas, whether produced by the same or different whales. The shared codas appear to have a function that is different from individual identification as hypothesized previously for some coda patterns.
Mark A. Hindell - One of the best experts on this subject based on the ideXlab platform.
-
concentrations of organochlorines in sperm whales Physeter macrocephalus from southern australian waters
Marine Pollution Bulletin, 2004Co-Authors: Karen Evans, Mark A. Hindell, Greg HinceAbstract:Abstract Concentrations of DDTs, PCBs and HCHs were measured in sperm whales involved in two mass stranding events on the west coast of Tasmania, Australia in February 1998. DDTs and PCBs were present in all samples analysed, while only three contained HCHs. The relationships between organochlorines, sex, age and reproductive groups were marked by high variability. Differences in organochlorine concentrations were observed between animals from the two stranding sites and discussed in light of the ecology of this species. Concentrations of all pollutants were stratified throughout the vertical aspect of the blubber and possible reasons for and the implications of this are discussed. Concentrations of compounds were higher than those documented in this species in the Southern Hemisphere previously, although were relatively lower than those documented in the Northern Hemisphere. However, comparisons were confounded by spatial and temporal differences. Continued monitoring of marine mammals throughout this region in a co-coordinated, standardized manner is essential for establishing definite temporal and spatial variations in pollutant concentrations.
-
the diet of sperm whales Physeter macrocephalus in southern australian waters
Ices Journal of Marine Science, 2004Co-Authors: Karen Evans, Mark A. HindellAbstract:Stomach contents were collected from 36 sperm whales (Physeter macrocephalus) involved in two mass stranding events during February 1998 along the west coastline of Tasmania, Australia. Contents were dominated by oceanic cephalopods, with a total of 101 883 cephalopod beaks representing 48 species from 14 families of Teuthids, two species from two families of Octopods, and a single Vampyromorph species identified. Species diversity was higher in these animals than other sperm whales studied in the southern hemisphere, with samples containing an average of (±s.d.) 28.4 ± 11.1 species per sample. Diet samples were dominated by subtropical and muscular cephalopod species. Members of the family Histioteuthidae were the most important numerically, and were also important in terms of estimated reconstituted mass, although members of the Onychoteuthidae were the most dominant species in samples in terms of estimated reconstituted mass. Other families numerically important to species composition included the cranchiid, lepidoteuthid, onychoteuthid, and pholidoteuthid families, while the architeuthid, pholidoteuthid, and ommastrephid families were also important in terms of reconstituted mass. Cephalopod species composition varied with stranding site and with sex, but not with age. However, differences did not represent systemic variation with groups marked by high individual variability. Lower rostral lengths of all cephalopod species ranged from 1.3 to 40.7 mm. Calculated dorsal mantle lengths from all species ranged from 10.7 to 2640.7 mm (mean ± s.d. = 233.7 ± 215.7 mm) and estimated wet weights of cephalopod prey ranged from 2.7 to 110 233.1 g (mean ± s.d. = 828.3 ± 3073.6 g). While there were differences in the size of some cephalopod species between stranding sites and with age, this was marked by high individual variability. Differences in diet composition and prey size between sperm whales reflect individual variability in foraging success and perhaps also foraging groups related to the social structure of this species. © 2004 International Council for the Exploration of the Sea. Published by Elsevier Ltd. All rights reserved.
Sarah L Mesnick - One of the best experts on this subject based on the ideXlab platform.
-
what influences the worldwide genetic structure of sperm whales Physeter macrocephalus
Molecular Ecology, 2016Co-Authors: Sarah L Mesnick, Alana Alexander, Debbie Steel, Kendra Hoekzema, Daniel Engelhaupt, Iain Kerr, Roger Payne, Scott C BakerAbstract:The interplay of natural selection and genetic drift, influenced by geographic isolation, mating systems and population size, determines patterns of genetic diversity within species. The sperm whale provides an interesting example of a long-lived species with few geographic barriers to dispersal. Worldwide mtDNA diversity is relatively low, but highly structured among geographic regions and social groups, attributed to female philopatry. However, it is unclear whether this female philopatry is due to geographic regions or social groups, or how this might vary on a worldwide scale. To answer these questions, we combined mtDNA information for 1091 previously published samples with 542 newly obtained DNA profiles (394-bp mtDNA, sex, 13 microsatellites) including the previously unsampled Indian Ocean, and social group information for 541 individuals. We found low mtDNA diversity (π = 0.430%) reflecting an expansion event <80 000 years bp, but strong differentiation by ocean, among regions within some oceans, and among social groups. In comparison, microsatellite differentiation was low at all levels, presumably due to male-mediated gene flow. A hierarchical amova showed that regions were important for explaining mtDNA variance in the Indian Ocean, but not Pacific, with social group sampling in the Atlantic too limited to include in analyses. Social groups were important in partitioning mtDNA and microsatellite variance within both oceans. Therefore, both geographic philopatry and social philopatry influence genetic structure in the sperm whale, but their relative importance differs by sex and ocean, reflecting breeding behaviour, geographic features and perhaps a more recent origin of sperm whales in the Pacific. By investigating the interplay of evolutionary forces operating at different temporal and geographic scales, we show that sperm whales are perhaps a unique example of a worldwide population expansion followed by rapid assortment due to female social organization.
-
can genetic differences explain vocal dialect variation in sperm whales Physeter macrocephalus
Behavior Genetics, 2012Co-Authors: Luke Rendell, Sarah L Mesnick, Merel L Dalebout, Jessica Burtenshaw, Hal WhiteheadAbstract:Sperm whale social groups can be assigned to vocal clans based on their production of codas, short stereotyped patterns of clicks. It is currently unclear whether genetic variation could account for these behavioural differences. We studied mitochondrial DNA (mtDNA) variation among sympatric vocal clans in the Pacific Ocean, using sequences extracted from sloughed skin samples. We sampled 194 individuals from 30 social groups belonging to one of three vocal clans. As in previous studies of sperm whales, mtDNA control region diversity was low (π = 0.003), with just 14 haplotypes present in our sample. Both hierarchical AMOVAs and partial Mantel tests showed that vocal clan was a more important factor in matrilineal population genetic structure than geography, even though our sampling spanned thousands of kilometres. The variance component attributed to vocal dialects (7.7%) was an order of magnitude higher than those previously reported in birds, while the variance component attributed to geographic area was negligible. Despite this, the two most common haplotypes were present in significant quantities in each clan, meaning that variation in the control region cannot account for behavioural variation between clans, and instead parallels the situation in humans where parent-offspring transmission of language variation has resulted in correlations with neutral genes. Our results also raise questions for the management of sperm whale populations, which has traditionally been based on dividing populations into geographic ‘stocks’, suggesting that culturally-defined vocal clans may be more appropriate management units.
-
characterization of 18 snp markers for sperm whale Physeter macrocephalus
Molecular Ecology Notes, 2007Co-Authors: Phillip A. Morin, Nadia Rubiocisneros, Andrew E. Dizon, Nicola C. Aitken, Sarah L MesnickAbstract:We report the characterization of 18 new single nucleotide polymorphism (SNP) markers for an endangered species, the sperm whale (Physeter macrocephalus), developed using a targeted gene approach. SNP markers were derived from autosomal regions of the genome using primers originally characterized for genome mapping in other mammals. These SNP markers are the first to be designed for genotyping sperm whale populations and will provide a necessary addition to the genetic tools employed for understanding population structure on a global scale and for developing a conservation management strategy for this endangered species.
