Postweaning behaviour in pups of the southern elephant seal (Mirounga leonina) on South Georgia

1997 ◽  
Vol 75 (4) ◽  
pp. 582-588 ◽  
Author(s):  
Anders Modig ◽  
Henri Engström ◽  
Tom Arnbom
Keyword(s):  
Vitamin D ◽  
Elephant Seal ◽  
Tooth Eruption ◽  
Southern Elephant Seal ◽  
Mirounga Leonina ◽  
South Georgia ◽  
Resting Behaviour ◽  
Significant Difference ◽  
Save Energy ◽  
Daytime Behaviour

After weaning, southern elephant seal pups (Mirounga leonina) fast for 3 – 8 weeks, for largely unknown reasons. During the postweaning fast we observed daytime behaviour and movements of pups on South Georgia in relation to mass, sex, and tooth eruption. There was variation in behaviour, with the lowest levels of activity from about 09:00 to 15:00. When ashore, weaned pups spent 97% of the time resting. There was no difference in activity between the sexes, except that only male pups were observed fighting. There was a significant difference in tooth eruption between the sexes. In female pups, 87.9% had teeth at weaning, while only 28.7% of male pups had. There was no correlation between mass at weaning and activity in either sex. Weaned pups tended to gather in groups (median group size 3, range 2 – 67). Several factors may affect the behaviour of pups during the postweaning fast: the resting behaviour required to save energy favours spending time ashore during the day (which also enhances vitamin D synthesis), and foraging is more effectively practiced at night because their prey is more active at night.

scholarly journals The northernmost haulout site of South American sea lions and fur seals in the western South Atlantic

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Natália Procksch ◽  
M. Florencia Grandi ◽  
Paulo Henrique Ott ◽  
Karina Groch ◽  
Paulo A. C. Flores ◽  
...  
Keyword(s):  
Mixed Model ◽  
Linear Mixed Model ◽  
Elephant Seal ◽  
Southern Elephant Seal ◽  
South American ◽  
Mirounga Leonina ◽  
Sea Lions ◽  
Significant Difference ◽  
Northern Portion ◽  
Kernel Density Analysis

AbstractWe present estimates of the seasonal and spatial occupation by pinnipeds of the Wildlife Refuge of Ilha dos Lobos (WRIL), based on aerial photographic censuses. Twenty aerial photographic censuses were analysed between July 2010 and November 2018. To assess monthly differences in the numbers of pinnipeds in the WRIL we used a Generalized Linear Mixed Model. Spatial analysis was carried out using Kernel density analysis of the pinnipeds on a grid plotted along the WRIL. Subadult male South American sea lions (Otaria flavescens) were the most abundant pinniped in the WRIL. Potential females of this species were also recorded during half of the census. The maximum number of pinnipeds observed in the WRIL was 304 in September 2018, including an unexpected individual southern elephant seal (Mirounga leonina), and a high number of South American fur seal yearlings (Arctocephalus australis). However, there was no statistically significant difference in counts between months. In all months analysed, pinnipeds were most often found concentrated in the northern portion of the island, with the highest abundances reported in September. This study confirms the importance of the WRIL as a haulout site for pinnipeds in Brazil, recommends that land research and recreational activities occur in months when no pinnipeds are present, and encourages a regulated marine mammal-based tourism during winter and spring months.

Cephalopod prey of the southern elephant seal, Mirounga leonina L.

1992 ◽  
Vol 70 (5) ◽  
pp. 1007-1015 ◽  
Author(s):  
P. G. Rodhouse ◽  
T. R. Arnbom ◽  
M. A. Fedak ◽  
J. Yeatman ◽  
A. W. A. Murray
Keyword(s):  
Elephant Seal ◽  
Southern Elephant Seal ◽  
Antarctic Polar Front ◽  
Mirounga Leonina ◽  
Important Species ◽  
Elephant Seals ◽  
South Georgia ◽  
Cephalopod Species ◽  
Southern Elephant Seals ◽  
The Antarctic

In the austral summers of 1986 and 1988–1989, 51 southern elephant seals (Mirounga leonina) at Husvik, South Georgia (54°10′S; 36°43′W), were stomach lavaged after chemical immobilization. Only cephalopod remains were retrieved, including 1070 lower beaks that were identified and measured. In total these were estimated to represent a wet weight of 187.8 kg. Fourteen species of squid from 11 families and 2 species of octopod from 1 family were present. The most important species overall were the squids Psychroteuthis glacialis in terms of numerical abundance (33.7%) and Moroteuthis knipovitchi in terms of estimated biomass (31.2%). The remaining biomass was mainly comprised of the five large muscular squids, Kondakovia longimana (24.0%), P. glacialis (15.4%), Martialia hyadesi (11.2%), Alluroteuthis antarcticus (10.8%), and Gonatus antarcticus (3.6%). Larger seals of both sexes fed on a wider variety of cephalopod species than smaller seals, with large males taking the greatest diversity. Between the two summers of the study there were some changes in the relative importance of the various cephalopod species consumed; in particular, in 1988–1989 M. knipovitchi and M. hyadesi were less important and P. glacialis was more important. The taxa and size of cephalopods taken by southern elephant seals at South Georgia are almost identical to those taken by the grey-headed albatross (Diomedea chrysostoma), but the relative proportions are quite different. The biogeography of the cephalopods eaten suggests that southern elephant seals sampled at South Georgia do not forage to the north of the Antarctic Polar Front but probably travel southwards towards the Antarctic continent or Peninsula.

A histochemical examination of the epidermis of the southern elephant seal (Mirounga leonina L.) during the telogen stage of hair growth

1968 ◽  
Vol 16 (1) ◽  
pp. 17 ◽  
Author(s):  
RIC Spearman
Keyword(s):  
Hair Growth ◽  
Outer Part ◽  
Elephant Seal ◽  
Basal Part ◽  
Southern Elephant Seal ◽  
Horny Layer ◽  
Mirounga Leonina ◽  
Disulphide Bonds ◽  
Sulphydryl Groups ◽  
Hair Shafts

The epidermal horny layer in the elephant seal, Mirounga leonina, is formed of dead, flattened, solidly keratinized cells without basophilic nuclear remnants. The basal part is more compacted than the outer part which is loosely arranged and has wide dorsoventral intercellular spaces, but the cornified cells appear firmly stuck together along their lateral junctions. Sloughing of the horny layer at the end of a season's growth appears to take place without the development of a specialized fission zone. This is in contrast to the sloughing mechanism in lizards and snakes. Keratin disulphide bonds are uniformly distributed in the horny layer but bound sulphydryl groups, calcium, and phospholipids are more concentrated in the basal part. At the telogen hair growth stage the epidermal horny layer was found to be closely united with the hair shafts within the insunken follicle necks. In these regions the compact junctional horny layer reacted for disulphide bonds, bound sulphydryl groups, phospholipids, and calcium. These substances also occurred in the hook-like keratinized cells which attached the resting club hair to the base of the follicle, but the hair keratin itself only reacted strongly for disulphide bonds. The possible significance of bound phospholipid in the horny layer in waterproofing the skin is discussed.

Studies on the ectoparasites of seals and penguins. 1. The ecology of the louse Lepidophthirus macrorhini Enderlein on the southern elephant seal, Mirounga leonina (L)

1965 ◽  
Vol 13 (3) ◽  
pp. 437 ◽  
Author(s):  
MD Murray ◽  
DG Nicholls
Keyword(s):  
Stratum Corneum ◽  
Skin Temperature ◽  
Elephant Seal ◽  
The Body ◽  
Southern Elephant Seal ◽  
Mirounga Leonina ◽  
Prolonged Stay ◽  
Blood Sucking ◽  
Southern Elephant Seals ◽  
Causes Of Mortality

Although the southern elephant seals, Mirounga leonina, that breed on Macquarie I., come ashore for only 3-5 weeks twice a year, the hind flippers of most of them are infested with the blood-sucking louse Lepidophthirus macrorhini. L. macrorhini does not oviposit, and eggs do not hatch, in water. Reproduction occurs when the elephant seal is ashore on the beach or in the adjacent tussock. The life cycle can be completed in c. 3 weeks and, because 6-9 eggs are laid daily, multiplication can be rapid. Temperatures greater than 25�C are required for rapid multiplication, and these temperatures occur more frequently on the hind flippers than elsewhere on the body. The number of L. macrorhini on a hind flipper however rarely exceeds 100. The principal causes of mortality of the lice are failure to survive the seal's prolonged stay at sea, the moult of the seal, and transmission to unfavourable sites on the seal. When an elephant seal goes to sea its skin temperature falls to nearly that of the sea. The reduction in the metabolic rate of the louse at low temperatures results in the amount of oxygen obtained from the sea by cutaneous respiration being sufficient for survival. The lice do not enter into a state of complete suspended animation, and a blood meal is required at least once a week to enable sufficient to survive to repopulate the seal. The skin temperature of a seal at sea rises more frequently on the flippers than elsewhere on the body because of the increased rate of blood flow to the flippers after diving and whenever it is necessary to dissipate heat. Consequently, there are more opportunities for the lice on the hind flippers to feed. L. macrorhini burrows into the stratum corneum, thus reducing losses to the population when the elephant seal annually sheds the outer layers of the stratum corneum attached to the hair, because only the roof of the burrow is lost. Lice do not reproduce on the older seals that moult in muddy wallows, and consequently fewer lice are found on these animals. Pups are infested within a few days of birth, and the gregarious habits of the elephant seal spread infestations through the seal population. Lice transfer to all parts of the bodies of seals but it is the multiplication of those on the flippers that maintains the louse population. The abundance of L. macrorhini is determined largely by the frequency and duration of opportunities to reproduce when the elephant seal is ashore, and to feed when the elephant seal is at sea.

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