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|Grey Seal - Halichoerus grypus|
|Topic Started: Jan 9 2012, 12:35 PM (427 Views)|
|Taipan||Jan 9 2012, 12:35 PM Post #1|
Grey Seal - Halichoerus grypus
Species: Halichoerus grypus
The Grey Seal (Halichoerus grypus, meaning "hooked-nosed sea pig") is found on both shores of the North Atlantic Ocean. It is a large seal of the family Phocidae or "true seals". It is the only species classified in the genus Halichoerus. Its name is spelled Gray Seal in the US; it is also known as Atlantic Grey Seal and the Horsehead Seal.
It is a medium sized seal, with the bulls reaching 2.5–3.3 m long and weighing up to 300 kg; the cows are much smaller, typically 1.6–2.0 m long and 100–150 kg weight. It is distinguished from the Common Seal by its straight head profile with nostrils that are well apart, and fewer spots on its body. Bull Grays have larger noses and a more convex profile than Common Seal bulls. Males are often darker than females, with lighter patches and often scarring around the neck. Females are silver grey to brown with dark patches.
Approximate Grey Seal range (in blue)
In Great Britain and Ireland, the Grey Seal breeds in several colonies on and around the coasts; notably large colonies are at Donna Nook (Lincolnshire), the Farne Islands off the Northumberland Coast (about 6,000 animals), North Rona off the north coast of Scotland, Lambay Island off the coast of Dublin and Ramsey Island off the coast of Pembrokeshire.
In the Western North Atlantic, the Grey Seal is typically found in large numbers in the coastal waters of Canada and south to about New Jersey in the United States. In Canada, it is typically seen in areas such as the Gulf of St. Lawrence, Newfoundland and the Maritimes, and Quebec. The largest colony in the world is at Sable Island. In the United States it's found year round off the coast of New England, in particular Maine and Massachusetts, and slightly less frequently in the Middle Atlantic States. Its natural range extends south to Virginia.
An isolated population exists in the Baltic Sea, forming the H. grypus balticus subspecies.
During the winter months Grey Seals can be seen hauled out on the rocks, islands, and shoals not far from shore, and occasionally coming ashore to rest. In the spring the recently weaned pups and yearlings occasionally strand on beaches after becoming "lost."
The Grey Seal feeds on a wide variety of fish, mostly benthic or demersal species, taken at depths down to 70 m (230 ft) or more. Sand eels (Ammodytes spp) are important in its diet in many localities. Cod and other gadids, flatfish, herring and skates are also important locally. However, it is clear that the Gray Seal will eat whatever is available, including octopus and lobsters. The average daily food requirement is estimated to be 5 kg (11 lb), though the seal does not feed every day and it fasts during the breeding season.
The pups are born in autumn (September to November) in the eastern Atlantic and in winter (January to February) in the west, with a dense, soft silky white fur; at first they are small and shrivelled-looking, but they rapidly fatten up to look like over-filled barrels, from the extremely fat-rich milk they receive from their mothers. Within a month or so, they shed the pup fur and grow the dense waterproof adult fur, and soon leave for the sea to learn to fish for themselves. In recent years, the number of Gray Seals has been on the rise in the west and in Canada there have been calls for a seal cull. However this does not appear to be coming to fruition any time soon.
In the United States Grey Seal numbers are increasing rapidly. Up until 1962, Maine and Massachusetts had bounties on seals so that only a few isolated colonies of Grey Seals remained in Maine. Then in 1972 Congress passed the Marine Mammal Protection Act that prevented harming or harassing seals, and Grey Seal populations rebounded. For example there is a large breeding colony near Cape Cod, Massachusetts, where pups rebounded from a handful in 1980 to more than 2,000 in 2008. By 2009, thousands of Grey Seals there had taken up residence on or near popular swimming beaches when Great White Sharks started hunting them close to shore. Also Grey Seals are seen increasingly in New York and New Jersey waters, and it's expected that they will establish colonies further south.
In the UK seals are protected under the Conservation of Seals Act 1970, however it does not apply to Northern Ireland. In the UK there have also been calls for a cull from some fishermen, claiming that stocks have declined due to the seals.
There are two recognized subspecies of this seal:
Halichoerus grypus grypus
Halichoerus grypus macrorhynchus, synonymously known as H. grypus balticus.
|Taipan||Jan 11 2012, 10:13 PM Post #2|
Baby grey seals face swim or suckle survival dilemma
By Matt Walker
Editor, Earth News
Page last updated at 04:56 GMT, Friday, 29 October 2010 05:56 UK
Suckle or swim?
For a grey seal pup, the first few days of life appear to be an insouciant affair.
Lying with mum, whiskers fluttering in a sea breeze, watching waves lap ashore.
But as the BBC launches a series of seal webcams - offering a unique opportunity to watch live footage of the animals as they breed on the coast of Scotland - new research published this month suggests that the life of a grey seal pup is anything but easy.
Baby grey seals have to make a series of life or death decisions.
And one of the most important is whether to suckle or swim.
Grey seals (Halichoerus grypus) occur worldwide along the western and eastern coasts of the North Atlantic and in the Baltic Sea.
More than 200,000 exist, with the majority occurring in the eastern North Atlantic, concentrating within the islands of Scotland, UK.
Females tend to return to the same breeding sites year after year, and around 15% of the world's grey seal population breeds on Orkney, Scotland.
Last year 5,000 pups were born on the beaches and rocky outcrops of the island of Stronsay alone.
Autumnwatch webcam footage of grey seals in Orkney taken on Thursday 28 October
This year, BBC Autumnwatch is broadcasting this spectacle using webcams to beam back live video footage of a seal colony breeding on the beach at Stronsay.
This live broadcast will continue for the next ten days, with wildlife cameraman Gordon Buchanan filming the creatures for the best part of a month.
But it is another major colony of seals, which breed at Froan, Norway, which has revealed the dilemma facing young pups.
Fast or feast
Grey seal pups are born with a white coat, and feed on their mother's milk for about 15 days.
After an abrupt weaning, by which time they have moulted their baby coat, they endure a fast lasting one to four weeks. During this time, they get most of their energy from their body fat.
But scientists studying seals at a Froan wildlife reserve observed pups engaging in two distinct behaviours - both while they were still suckling and after they had been weaned.
Around 40% of the pups studied spent their time ashore, scientists from the Norwegian University of Science and Technology and the Norwegian Polar Institute report in the journal Animal Behaviour.
The other 60% of pups entered the sea during suckling and in the early post weaning period. These pups regularly dispersed to other locations within the breeding colony.
Some of these more adventurous ones swam distances of up to 12km.
The dilemma is very real. Starvation is reported to be a major cause of death among young grey seals in the UK.
So it is risky for a pup to leave its mother - and its food source - and burn energy learning how to swim.
Young seals are also exposed to colder temperatures in the water. They could surface or haul out at a different site, losing contact with their parent.
But not learning to swim brings its own risks; seals that have not learnt to dive and forage may not be able to feed themselves as well during their first year.
The scientists studying the Froan seals found that suckling pups that dispersed more than 2km had a significantly lower body mass than those that remained on shore, many of which suckled for longer.
But the more adventurous pups later caught up in body weight, suggesting they were better placed to feed themselves.
Such decisions influence the fate of individual pups and also the fate of the overall population.
Recent research has found that grey seal populations can be self-limiting, fluctuating according to the density of seals in any given year.
For example, the overall British grey seal population has been regularly monitored using aerial surveys for the past four decades.
Until 1996, the population had been increasing at a rate of 5-6%, but between 1997 and 2001 the rate fell to 2.8%.
It then continued to fall, growing by just 1.3% between 2001 and 2005, suggesting it was being regulated by some density dependent process.
Studies on the Isle of May, Scotland point to what that might be.
Females need to cool down
Scientists at the University of St Andrews, UK observed and then modelled the distribution of newborn grey seal pups.
They found that the first breeding females to arrive generally lay their newborn pups close to the sea, but few closer than 10m to the point where they access the ocean.
Later arriving females are then forced to give birth inland, some up to 100m further away from the sea.
As more seals arrive it therefore becomes harder to find a suitable pupping site, which may limit the growth of the overall population.
Aggression also plays a significant role, particularly within the most dense parts of the colony, between 20 and 60m from the sea.
Here females are most likely to attack one another, with most aggressive encounters occurring close to freshwater pools.
Grey seals are thought to use these inland pools of water to help cool their bodies and possibly for drinking.
|Taipan||Jan 11 2012, 10:14 PM Post #3|
|Taipan||Oct 13 2012, 10:37 PM Post #4|
Pet owner watches in horror as his labrador is dragged into sea and killed by a seal as it played in the surf
'He was pouring with blood and in spasms of agony. I'm still trying to come to terms with it all,' said owner Matthew Will
By ANNA EDWARDS
PUBLISHED: 10:42 GMT, 9 October 2012 | UPDATED: 08:46 GMT, 10 October 2012
A pet owner watched in horror as his dog was mauled to death after being dragged under water by a seal.
Matthew Will, 21, had taken his labrador Fly to an Aberdeenshire beach so his dog could fetch the bodies of ducks that he was shooting.
As Fly ran into the water to pick up a bird a seal pulled the three-year-old dog beneath the water and ripped into it.
Fly had been helping his owner when the huge seal 'threw him around in the water' and he suffered fatal injuries
Mr Will ran into the water to try and save his pet but it was too late for Fly, who had suffered fatal injuries.
The dog died after he was attacked in the North Sea near Newburgh, Aberdeenshire.
Mr Will, of Inverugie, Peterhead, said: 'There was a sudden and terrific thrashing and howling in the water.
'I shone my torch towards where Fly had gone in to bring out the duck.
'But this huge seal, more than twice the size of the dog, was flinging Fly around and pulling him under the water. I was horrified. The seal was enormous.
'Both his hind legs were completely crushed and mangled, his rib cage smashed and his left eye torn out. He was pouring with blood and in spasms of agony.
'I’m still trying to come to terms with it all. Now I just want to warn other dog-owners of the danger so that they won’t have to face the same anguish and horror that I have.'
Fly was killed by the seal on Friday evening after running into the water at the mouth of the Tarty Burn river.
Local environmentalist Bob Davis said attacks by seals were very rare and unusual.
He said: 'Seals are fish-eaters, and the attack on the dog may have been a defensive response.'
Local fishery manager Audrey Forbes-Clarke said warning signs had now been installed.
Culprit: One of the huge seals ripped into the faithful pet dog as it raced ot find a duck
Normally regarded as adorable sea creatures, the grey seal (known as the hook-nosed sea pig) is actually a formidable creature.
Bulls can reach 8 to 11 ft long and weigh between 170–310 kg, while the cows are much smaller, typically sized between 5 and 6.6 ft long and reaching between 100 to 190 kg in weight.
The grey seal breeds in colonies around the northern coasts of Great Britain and Ireland and are protected by a Conservation Act.
The curious creatures, who can be seen basking on rocks and on sand, typically eat shellfish, fish and octopus.
Read more: http://www.dailymail.co.uk/news/article-2215050/Seal-mauls-labrador-death-dragged-water-went-retrieve-ducks.html#ixzz29BSsINA4
|Taipan||Nov 21 2012, 04:53 PM Post #5|
Seals Gamble With Their Pups' Futures
ScienceDaily (Nov. 20, 2012) — Some grey seal mums adopt risky tactics when it comes to the future of their young, a strategy that can give their pup a real advantage, according to scientists.
Researchers from Durham University and the University of St Andrews, looking at grey seal colonies in Scotland, found that some seal mothers are flexible in the parenting style they adopt and 'gamble' on the outcome of their actions, whilst other play it safe and steady.
The study is the first to demonstrate how variation in personality traits in large marine mammals in the wild can persist, rather than a single, successful, personality type dominating the population.
The research shows that some seal mothers have a very fixed approach to looking after their pups, and tend to behave in a similar fashion whatever the local conditions on the breeding colony are; whether they are in a crowded and busy location, or in a less disturbed situation. These mums tend to achieve average success in terms of their pups' weight gain (crucial to the future survival of the pup), so that, by-and-large, they generally do well. These mums seem to have a 'play it safe' approach to life.
Some seal mothers have a very different approach. These mums are more flexible and try to adjust their mothering behaviour according to the local conditions. In potentially unpredictable situations, this can be risky; sometimes they get it right and their pups fare very well, but other times they might get it wrong and their pups do rather badly.
The findings, published in the journa lPLoS One, show that individual animals can differ markedly in their ability to adjust their behaviour to their local environmental conditions and that large variations in behavioural strategies can persist within a species.
According to the researchers, the results for both extremes of personality show how different types can be maintained by selection. This retains behavioural diversity within a species, potentially making the species more resilient to environmental change.
The results are relevant to environment and conservation policies that use a one-size-fits-all approach, as these may need to be re-evaluated to take into account individual differences in animal personality, the researchers say.
Lead author, Dr Sean Twiss, School of Biological and Biomedical Sciences, said: "Some mums have a very fixed way of caring for their pups, come what may, whilst others are more flexible.
"Seals that 'gamble' and try to fit their behaviour to their immediate surroundings can do very well, if they get it right! However, being flexible can be risky -- a mum might 'mis-judge' the conditions and fail to match her behaviour to the prevailing conditions.
"In either resting or disturbed situations, seal mums behaved in very individual ways, some showing high levels of maternal attentiveness, others showing low levels. Some behaved the same when disturbed as they did at rest while other individuals changed their behaviour dramatically when disturbed."
These differences in mothers' behaviour, either fixed or flexible, can have profound effects on their pups. After about 2 weeks of being looked after by their mothers, all pups are left to fend for themselves, and have to teach themselves to feed. The fatter a mum leaves her pup, the more time the pup has to learn, and its chances of surviving are better.
The scientists observed seals on the Scottish island of North Rona during the breeding season over two years. The team observed seals in their natural habitat to analyse responses to unusual stimuli (disturbances) and to assess seal behaviour at rest.
Co-author Dr Paddy Pomeroy said: "What's really interesting about these short term tests is the way behavioural types map onto individual measures of reproductive success. If more flexible mothers are better and worse pup rearers, one of our next tasks will be to see how breeding successes and failures are apportioned over lifetimes, which can only be done in this type of study."
The research has been part-funded by NERC, The Living With Environmental Change partnership, and the Esmée Fairburn Foundation.
Sean D. Twiss, Charlotte Cairns, Ross M. Culloch, Shane A. Richards, Patrick P. Pomeroy. Variation in Female Grey Seal (Halichoerus grypus) Reproductive Performance Correlates to Proactive-Reactive Behavioural Types. PLoS ONE, 2012; 7 (11): e49598 DOI: 10.1371/journal.pone.0049598
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