Social structure and mating system of sperm whales off northern Chile

2004 ◽  
Vol 82 (8) ◽  
pp. 1360-1369 ◽  
Author(s):  
Amanda K Coakes ◽  
Hal Whitehead
Keyword(s):  
Social Structure ◽  
Mating System ◽  
Relative Abundance ◽  
Northern Chile ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
The Social ◽  
Mean Size ◽  
Males And Females ◽  
The Mean

We studied the social structure and mating system of sperm whales (Physeter macrocephalus L., 1758) off northern Chile over 10 months in 2000, photographically identifying 898 individuals. The mean size of encountered groups of females with immatures was about 23 animals, while the estimated mean size of units (sets of females and immatures with permanent relationships) was 11 animals. About 4% of the population consisted of large mature males, although this varied seasonally. Groups of females and immatures, as well as large males, spent only a matter of days within the study area at a time. There was no evidence for preferred ranges for the males, for males consistently accompanying particular groups, or for males forming coalitions. Males roved between the groups of females and immatures. Both mature males and females or immatures appeared to take the initiative in maintaining or breaking close associations. These results are similar to those from studies off the Galápagos Islands, even though the habitat, nonsocial behaviour, and relative abundance of mature males were quite different in the two areas.

Temporal and geographic variation in the social structure of female sperm whales

1992 ◽  
Vol 70 (11) ◽  
pp. 2145-2149 ◽  
Author(s):  
Hal Whitehead ◽  
Benjamin Kahn
Keyword(s):  
Social Structure ◽  
Galapagos Islands ◽  
General Area ◽  
Physeter Macrocephalus ◽  
Galápagos Islands ◽  
Sperm Whales ◽  
The Social ◽  
Seychelles Islands ◽  
Mean Size ◽  
Geographic Differences

The social structure of female sperm whales (Physeter macrocephalus) was examined from data collected during studies of identified individuals off the Galápagos Islands in 1985, 1987, and 1989, off the Seychelles Islands in 1990, and off mainland Ecuador in 1991. Three levels of social organization were examined in the Galápagos Islands studies. "Units," permanent associations between individuals, showed no significant deviation from a mean size of 13 individuals. "Groups," temporary associations between units lasting a few days, had a mean size of 24 individuals. Group size was lower in 1987 (an "El Niño" year) than in 1985 or 1989, but this difference was not statistically significant. "Aggregations" of groups in the same general area lasting periods of hours were significantly larger in 1985 (mean of 77 individuals) than in 1987 (mean of 47 individuals). There are significant differences between areas in aggregation sizes but not in group sizes. Groups appear to aggregate frequently off the Galápagos Islands, occasionally off mainland Ecuador, and very rarely off the Seychelles Islands. These temporal and geographic differences in sizes of groups and aggregations in sperm whales are probably caused by variations in the distribution and abundance of their food, but responses to recent exploitation may also be a factor.

scholarly journals Long-term associations among male sperm whales (Physeter macrocephalus)

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0244204
Author(s):  
Hayao Kobayashi ◽  
Hal Whitehead ◽  
Masao Amano
Keyword(s):  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Association Rate ◽  
Photo Identification ◽  
Male Sperm ◽  
The Social ◽  
Pelagic Habitat ◽  
Best Fitting ◽  
Social Associations

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.

Testing the resource economic monopolization hypothesis and its consequences for the mating system ofAlpheus estuariensis(Decapoda, Caridea, Alpheidae)

2018 ◽  
Vol 99 (3) ◽  
pp. 639-647
Author(s):  
Danillo Barroso ◽  
Douglas Fernandes Rodrigues Alves ◽  
Gustavo L. Hirose
Keyword(s):  
Mating System ◽  
Environmental Conditions ◽  
Social Behaviour ◽  
Random Distribution ◽  
Great Abundance ◽  
North East ◽  
The Social ◽  
Average Abundance ◽  
Males And Females

The aim of the present study is to test the resource economic monopolization hypothesis and the hypothesis of monogamy using the shrimpAlpheus estuariensisas a model. The shrimps were collected in two areas in the Vaza-Barriz estuary, north-east Brazil, from August to November 2016. The average abundance of refuges was obtained through 30 random replicates. The shrimp presented a random distribution in both areas. Males and females found together showed a weak relation between their sizes, with males being larger than females. In addition, the cheliped of males grows proportionally more than that of females. The great abundance of refuges present in the environment, added to the aforementioned results, do not support the idea of refuge-guarding behaviour or monogamy. These results, which are in disagreement with those already found for some shrimps of the same family, genus, and even species, reinforce the idea that Alpheidae can be used as a model in the study of how environmental conditions are capable of shaping the social behaviour of a species.

scholarly journals Social structure and residency in aggregations of male sperm whales

2002 ◽  
Vol 80 (7) ◽  
pp. 1189-1196 ◽  
Author(s):  
Erland Lettevall ◽  
Christoph Richter ◽  
Nathalie Jaquet ◽  
Elizabeth Slooten ◽  
Steve Dawson ◽  
...  
Keyword(s):  
Social Structure ◽  
Social Structures ◽  
Spatial Proximity ◽  
Residence Times ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Apparent Lack ◽  
Male Sperm ◽  
Close Spatial Proximity

Sperm whales (Physeter macrocephalus) are sexually dimorphic in several respects, including size, latitudinal distribution, and social structure. Females are known to have complex social structures, including long-term bonds, but the social structures of sexually mature or maturing males have received much less attention. Using data from aggregations of males off Norway, Nova Scotia, New Zealand, and the Galápagos Islands, we examined aggregation size, residence times within aggregations, clustering at the surface, and long-term bonds. Results were generally consistent among study areas. The aggregations found in each area contained around 10–30 males at any time, and were usually a few tens of kilometres across. Mean residence times within aggregations ranged from a few days to a few weeks. Close clustering at the surface was rare, but present at each site. There was no evidence for preferred companionship between individuals at any temporal scale in any of the study areas. The rarity of clustering and the apparent lack of long-term relationships amongst male sperm whales contrast strongly with results of studies on females, suggesting that both close spatial proximity at the surface and permanent bonds between individuals may be a consequence of the need for care of the young.

The social organisation and mating system of an Australian subalpine rodent, the broad-toothed rat, Mastacomys fuscus Thomas

1993 ◽  
Vol 20 (4) ◽  
pp. 405 ◽  
Author(s):  
TM Bubela ◽  
DCD Happold
Keyword(s):  
Mating System ◽  
Social Organisation ◽  
Home Ranges ◽  
Spatial Organisation ◽  
Nest Sites ◽  
Alpine Regions ◽  
The Social ◽  
Eastern Australia ◽  
The World ◽  
Males And Females

Mastacomys fuscus is a grass-eating rodent of south-eastern Australia that lives mainly in subalpine habitats where snow covers the ground for about four months of the year. Radiotelemetry revealed that in summer the females were territorial. Home ranges of males were larger than those of females and overlapped extensively with the home ranges of other males and with the home ranges of up to three females. In winter, males and females huddled together in communal nests. The locations of nest sites, cover, water and grass also determined the spatial organisation of individuals. The evidence suggests that M. fuscus is not monogamous, but there were insufficient data to determine whether polygyny or promiscuity is the preferred mating system. The social organisation of this species, solitary in summer and communal in winter, is a response to the cold snowy winters and the limited time for reproduction in summer. The social organisation of M, fuscus is different from that of the other conilurine rodents of Australia, but similar to that of rodents that live in other alpine regions of the world.

scholarly journals Calves as social hubs: dynamics of the social network within sperm whale units

2013 ◽  
Vol 280 (1763) ◽  
pp. 20131113 ◽  
Author(s):  
Shane Gero ◽  
Jonathan Gordon ◽  
Hal Whitehead
Keyword(s):  
Social Relationships ◽  
Social Role ◽  
Group Formation ◽  
Time Lag ◽  
Group Living ◽  
Sperm Whale ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Social Unit ◽  
The Social

It is hypothesized that the primary function of permanent social relationships among female sperm whales ( Physeter macrocephalus ) is to provide allomothers for calves at the surface while mothers make foraging dives. In order to investigate how reciprocity of allocare within units of sperm whales facilitates group living, we constructed weighted social networks based on yearly matrices of associations (2005–2010) and correlated them across years, through changes in age and social role, to study changes in social relationships within seven sperm whale units. Pairs of association matrices from sequential years showed a greater positive correlation than expected by chance, but as the time lag increased, the correlation coefficients decreased. Over all units considered, calves had high values for all measured network statistics, while mothers had intermediate values for most of the measures, but high values for connectedness and affinity. Mothers showed sharp drops in strength and connectedness in the first year of their new calves' lives. These broad patterns appear to be consistent across units. Calves appeared to be significant nodes in the network of the social unit, and thus provide quantitative support for the theory in which communal care acts as the evolutionary force behind group formation in this species.

scholarly journals Density and Size Distribution of the Sea Cucumber, Holothuria scabra (Jaeger, 1935), at Six Exploited Sites in Mahout Bay, Sultanate of Oman

2007 ◽  
Vol 12 ◽  
pp. 43 ◽  
Author(s):  
Khalfan M. Al-Rashdi ◽  
Michel R. Claereboudt ◽  
Saud S. Al-Busaidi
Keyword(s):  
Size Distribution ◽  
Sea Cucumber ◽  
Size Distributions ◽  
Sultanate Of Oman ◽  
Population Densities ◽  
Sea Cucumbers ◽  
Holothuria Scabra ◽  
Mean Size ◽  
Males And Females ◽  
The Mean

A rapid survey of the density and size distribution of recently exploited populations of Holothuria scabra in Mahout Bay (Ghubbat Hashish Bay) was carried out at six fishing sites. The results showed that population densities varied between 1170 and 4000 individuals ha-1 and biomass ranged between 393 and 2903 kg ha-1. The mean size of sea cucumbers and population densities were much lower in populations closer to human settlements, suggestive of overfishing. The sex ratio was estimated to be 1:1 and the size distributions of males and females did not differ significantly. The length-weight relationship for both sexes was calculated as W (g) = 0.033 Length (mm) 2.178. 

scholarly journals Vocal repertoires and insights into social structure of sperm whales ( Physeter macrocephalus ) in Mauritius, southwestern Indian Ocean

2020 ◽  
Vol 36 (2) ◽  
pp. 638-657
Author(s):  
Léonie A. E. Huijser ◽  
Vanessa Estrade ◽  
Imogen Webster ◽  
Laurent Mouysset ◽  
Adèle Cadinouche ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Social Structure ◽  
Physeter Macrocephalus ◽  
Sperm Whales ◽  
Southwestern Indian Ocean

Inferring the mating system in the burrowing shrimp Lepidophthalmus bocourti (Decapoda, Axiidea, Callichiridae) from the social structure and sexual dimorphism

2021 ◽  
Vol 75 (6) ◽  
Author(s):  
Patricio Hernáez ◽  
Erick Villegas-Castro ◽  
Marcio Camargo Araujo João ◽  
Rafael Campos Duarte ◽  
Marcelo M. Rivadeneira
Keyword(s):  
Sexual Dimorphism ◽  
Social Structure ◽  
Mating System ◽  
The Social

scholarly journals The diet of sperm whales (Physeter macrocephalus) in southern Australian waters

2004 ◽  
Vol 61 (8) ◽  
pp. 1313-1329 ◽  
Author(s):  
Karen Evans ◽  
Mark A. Hindell
Keyword(s):  
Species Composition ◽  
Diet Composition ◽  
Stomach Contents ◽  
Individual Variability ◽  
Physeter Macrocephalus ◽  
Foraging Success ◽  
Sperm Whales ◽  
Cephalopod Species ◽  
The Social ◽  
The Family

Abstract 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.

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