Remarks on display functions of the snout of the grey seal, Halichoerus grypus (Fab.), with comparative notes

1979 ◽  
Vol 57 (1) ◽  
pp. 140-148 ◽  
Author(s):  
E. H. Miller ◽  
D. J. Boness
Keyword(s):  
Visual Display ◽  
Halichoerus Grypus ◽  
Grey Seal ◽  
Adult Males ◽  
Hooded Seal ◽  
Elephant Seals ◽  
Sea Lions ◽  
Cystophora Cristata ◽  
Fur Seals ◽  
Threat Displays

Adult males of the grey seal, Halichoerus grypus (Fab.) (Phocidae), display the large snout conspicuously in threats. The male's snout has probably evolved through sexual selection as a visual display organ, as in some other extant phocids: the hooded seal, Cystophora cristata (Nilsson) and the two species of elephant seals, Mirounga (Gray). This may also be true of the extinct desmatophocid Allodesmus Kellogg. Cephalic display organs in the form of long tusks have also evolved twice in the Odobenidae (walruses). Comparable display structures do not occur in the Otariidae (fur seals and sea lions). However, the massive neck of adult male otariids is important in undirected static-optical threat displays, especially at long range, and in some kinds of short-range threats. Also, adult otariids show sexual dimorphism in facial appearance, which varies interspecifically.Pinniped species in which large mature males have prominent, constant-growing cephalic display structures show fluid spacing among rutting males, and much agonistic communication at the water surface and on land or ice. This correlation may reflect selective pressures on males to affirm social status repeatedly, through displays which communicate their age (hence strength and experience), and their resource-accruing abilities.

Individual variation in predation on fur seals by southern sea lions (Otaria byronia) in Peru

1993 ◽  
Vol 71 (9) ◽  
pp. 1908-1911 ◽  
Author(s):  
Robert Harcourt
Keyword(s):  
Adult Female ◽  
Individual Variation ◽  
Small Proportion ◽  
South American ◽  
Adult Males ◽  
Sea Lion ◽  
Subadult Male ◽  
Sea Lions ◽  
Hunting Success ◽  
Fur Seals

Southern sea lions (Otaria byronia) were observed to prey on juvenile and adult female South American fur seals (Arctocephalus australis) at Punta San Juan, Peru (15°22′S, 75°12′W) between October 1987 and December 1988. Over the course of the study there were 165 attacks on fur seals with 33 seals killed. While both adult male and subadult male sea lions captured and killed fur seals, adult female and juvenile sea lions never acted aggressively towards fur seals. Adult males attacked fur seals on 82.4% of the occasions when they were present at the rookery, subadults on 52% of occasions. Distinctive pelage characteristics allowed some of the male sea lions to be individually identified, and differences in hunting success were observed between adults and subadults, and between five identifiable adults who hunted on at least five occasions. Motivation for attacks differed for subadults and adults, with subadult males using captured fur seals as female sea lion substitutes, guarding them from others and copulating with them, whilst adult sea lions hunted fur seals as food. However, only a small proportion of adult sea lions hunted fur seals, and with differing rates of success.

Juvenile Play of the Common Seal Phoca Vit Ulina Vit Ulina With Comparative Notes On the Grey Seal Halichoerus Grypus

Behaviour ◽  
1974 ◽  
Vol 48 (1-4) ◽  
pp. 37-60 ◽  
Author(s):  
Susan Wilson
Keyword(s):  
Halichoerus Grypus ◽  
Grey Seal ◽  
Adult Males ◽  
Contact Phase ◽  
Body Contact ◽  
Static Contact ◽  
Continuous Body ◽  
The Common ◽  
Dyadic Play ◽  
Group Play

AbstractJuveniles of the common seal, Phoca vitulina, have two kinds of aquatic play : (1) Dyadic play, in which muzzle-to-body and body contact between two animals is combined with exuberant somersaulting movements. The somersaulting behaviour is usually preceded by a contact phase with very little movement. A play bout may end with a period of sustained, almost static contact. (2) Group play, which resembles the normal social haul-out activities, but each activity is repeated several times in a playful manner. Although several animals may be leaping and splashing simultaneously, each animal temporarily orients his play towards one other, whom it may contact briefly. All play by juveniles of the grey seal, Halichoerus grypus, is preceded by each animal of the dyad giving a stereotyped invitation signal, which must be repeated continually by both animals throughout play : each animal in turn lays its head over its partner's back. For the initial phase of play which takes place on the beach, the two animals lie beside one another, each lunging gently at the other's head, in between head-over-back signals. Adolescents may occasionally rear up and lunge at each other in a manner similar to the fighting of adult males. After playing on the beach, the pair may enter the water, where their play is similar to the dyadic play of the common seal. The aquatic somersaulting over one another by two animals in continuous body contact seems to be a pattern not found in these two species in other functional contexts. Common seal group play serves to (i) integrate the individuals into a unified group, and (ii) acquaint individuals. Although grey seals apparently do not have group play, behaviour which is probably functionally analogous was observed, in which the seals became acquainted over a 3-week period in early autumn before any play occurred.

Implications of a comparison of the airbourne vocalizations and some aspects of teh behaviuo of the two Australian fur seals, Arctocephalus spp., on the evolution and present taxonomy of the genus

1971 ◽  
Vol 19 (3) ◽  
pp. 227 ◽  
Author(s):  
I Stirling ◽  
RM Warneke
Keyword(s):  
High Intensity ◽  
Taxonomic Position ◽  
Adult Males ◽  
Sea Lions ◽  
Adult Females ◽  
Fur Seals ◽  
Female Attraction ◽  
First Time

The structure and number of airborne vocalizations of Arctocephalus pusillus doriferus and A. forsteri were studied. Four types of calls were compared: the pupattraction call given by adult females; the female-attraction call given by pups; the high-intensity guttural threat given by adult males; and, the repetitive barking call given by adult males. Male A. fovsteri gave two additional threat calls not present in A. p. doriferus. The structure and number of the calls given by the two species are substantially different. They here then compared to the calls of other members of the genus for which data were available and it became evident there were two vocal types within the genus Arctocephalus. We believe this is the first time such a situation has been reported in mammals. In addition to vocalizations, data on behaviour and morphology are presented to show the enigmatic taxonomic position, between the fur seals and the sea lions, occupied by A. pusillus.

Mass transfer from mother to pup and subsequent mass loss by the weaned pup in the hooded seal, Cystophora cristata

1987 ◽  
Vol 65 (1) ◽  
pp. 1-8 ◽  
Author(s):  
W. D. Bowen ◽  
D. J. Boness ◽  
O. T. Oftedal
Keyword(s):  
Mass Transfer ◽  
Weight Loss ◽  
Body Weight ◽  
Lactation Period ◽  
Fasting Period ◽  
Hooded Seal ◽  
Elephant Seals ◽  
Cystophora Cristata ◽  
Northern Elephant Seals ◽  
Efficient Transfer

We studied the components of mass transfer from mother to pup during the lactation period and weight loss by fasting pups postweaning in the hooded seal, Cystophora cristata. Measurements were taken from 33 mother–pup pairs and 69 weaned pups. Mean body weight of mothers declined from an average of 179 kg at the beginning of lactation to 150 kg for mothers nursing fat pups near the end of lactation. Over 80% of this weight loss was from the sculp (i.e., skin and blubber). Pup weight doubled during the 4 days of lactation, with about 70% of this weight gain in the form of blubber. Fasting pups lost 29% or 13 kg of their body weight between weaning and mid to late April when feeding begins. Sculp and core weight accounted for 51% and 49%, respectively, of total weight loss during this fasting period. Hooded seal mothers invest a smaller portion of their stored fat (33%) in their pup than do grey seals (85%) and northern elephant seals (58%). Our hooded seal data are consistent with the hypothesis that the abbreviation of lactation allows a reduction in overhead costs and more efficient transfer of nutrients from mother to pup.

Utilizing next-generation sequencing to identify prey DNA in western North Atlantic grey seal Halichoerus grypus diet

2020 ◽  
Vol 655 ◽  
pp. 227-240
Author(s):  
KR Flanders ◽  
ZH Olson ◽  
KA Ono
Keyword(s):  
Next Generation Sequencing ◽  
Feeding Habits ◽  
Atlantic Menhaden ◽  
Halichoerus Grypus ◽  
Frequency Of Occurrence ◽  
Grey Seal ◽  
Next Generation ◽  
Significant Difference ◽  
Generation Sequencing ◽  
Seal Diet

Increasing grey seal Halichoerus grypus abundance in coastal New England is leading to social, political, economic, and ecological controversies. Central to these issues is the foraging ecology and diet composition of the seals. We studied grey seal feeding habits through next-generation sequencing of prey DNA using 16S amplicons from seal scat (n = 74) collected from a breeding colony on Monomoy Island in Massachusetts, USA, and report frequency of occurrence and relative read abundance. We also assigned seal sex to scat samples using a revised PCR assay. In contrast to current understanding of grey seal diet from hard parts and fatty acid analysis, we found no significant difference between male and female diet measured by alpha and beta diversity. Overall, we detected 24 prey groups, 18 of which resolved to species. Sand lance Ammodytes spp. were the most frequently consumed prey group, with a frequency of occurrence (FO) of 97.3%, consistent with previous studies, but Atlantic menhaden Brevoortia tyrannus, the second most frequently consumed species (FO = 60.8%), has not previously been documented in US grey seal diet. Our results suggest that a metabarcoding approach to seal food habits can yield important new ecological insights, but that traditional hard parts analysis does not underestimate consumption of Atlantic cod Gadus morhua (FO = 6.7%, Gadidae spp.) and salmon Salmo salar (FO = 0%), 2 particularly valuable species of concern.

Predation by Sharks on the Grey Seal (Halichoerus grypus) in Eastern Canada

1983 ◽  
Vol 40 (3) ◽  
pp. 267-271 ◽  
Author(s):  
Paul Brodie ◽  
Brian Beck
Keyword(s):  
Key Words ◽  
Population Size ◽  
Halichoerus Grypus ◽  
Longline Fishery ◽  
Grey Seal ◽  
Eastern Canada ◽  
The Past ◽  
Harbour Seals ◽  
Commercially Important ◽  
Important Fish

The increase in population size of the grey seal (Halichoerus grypus) off eastern Canada over the past 20 yr may be attributed to a decrease in shark stocks, their supposed predators. Reduction of the shark population is presumed to have resulted from a directed longline fishery and, of greater significance, from a change in the fishery for swordfish (Xiphias gladius) from selective harpooning to pelagic longlining, which has produced a large bycatch of sharks. The resulting enhanced survival of grey seals is reflected in greater infestation of commercially important fish species by the codworm (Phocanema decipiens).Key words: grey seals, harbour seals, sharks, swordfish, codworm, predation, fisheries

scholarly journals Diving deep into trouble: the role of foraging strategy and morphology in adapting to a changing environment

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Monique Ladds ◽  
David Rosen ◽  
Carling Gerlinsky ◽  
David Slip ◽  
Robert Harcourt
Keyword(s):  
Foraging Strategy ◽  
Central Place ◽  
Dive Duration ◽  
Foraging Strategies ◽  
Body Morphology ◽  
Sea Lions ◽  
Fur Seals ◽  
Adequate Food ◽  
Physiological Capacity ◽  
Total Body Oxygen

Abstract Physiology places constraints on an animal’s ability to forage and those unable to adapt to changing conditions may face increased challenges to reproduce and survive. As the global marine environment continues to change, small, air-breathing, endothermic marine predators such as otariids (fur seals and sea lions) and particularly females, who are constrained by central place foraging during breeding, may experience increased difficulties in successfully obtaining adequate food resources. We explored whether physiological limits of female otariids may be innately related to body morphology (fur seals vs sea lions) and/or dictate foraging strategies (epipelagic vs mesopelagic or benthic). We conducted a systematic review of the increased body of literature since the original reviews of Costa et al. (When does physiology limit the foraging behaviour of freely diving mammals? Int Congr Ser 2004;1275:359–366) and Arnould and Costa (Sea lions in drag, fur seals incognito: insights from the otariid deviants. In Sea Lions of the World Fairbanks. Alaska Sea Grant College Program, Alaska, USA, pp. 309–324, 2006) on behavioural (dive duration and depth) and physiological (total body oxygen stores and diving metabolic rates) parameters. We estimated calculated aerobic dive limit (cADL—estimated duration of aerobic dives) for species and used simulations to predict the proportion of dives that exceeded the cADL. We tested whether body morphology or foraging strategy was the primary predictor of these behavioural and physiological characteristics. We found that the foraging strategy compared to morphology was a better predictor of most parameters, including whether a species was more likely to exceed their cADL during a dive and the ratio of dive time to cADL. This suggests that benthic and mesopelagic divers are more likely to be foraging at their physiological capacity. For species operating near their physiological capacity (regularly exceeding their cADL), the ability to switch strategies is limited as the cost of foraging deeper and longer is disproportionally high, unless it is accompanied by physiological adaptations. It is proposed that some otariids may not have the ability to switch foraging strategies and so be unable adapt to a changing oceanic ecosystem.

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