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Sunday, February 20, 2011

Antarctic Wildlife - Humpback Whales

 Due to heavy whaling activities during the mid 1800's and up to 1966, the humpback whale is now on the vulnerable species list. Since the moratorium in 1966, some numbers have increased in the southern ocean. It's a social creature moving in pods of 12 - 15 individuals. Its diving can last up to 20 minutes but usually lasts between 3 to 15 minutes and reaching depths of around 150m. They eat small school fish and krill. They spiral dive below the schools of feed to capture it in a "bubble net." This net can be up to 45m across making it easy to engulf when swimming at speed through it. It grows to around 11- 19m in length and a weight of 25 - 35 tonnes. As an Australian, I see these big fellas up the Queensland and Western Australian coasts. The humpbacks that migrate up the Australian coastlines usually come from East Antarctica.

Saturday, February 19, 2011

Antarctic Wildlife - Weddell Seal


The 'ol Weddell seal is probably the most common seal seen around Casey station where I'm currently based. Being one of the bigger seals, they are easy to spot. Around the 500kg mark and some 3.0m in length. We've mainly seen them as a solitary animal, but on occasion we've seen a pair pulled up on the same ice flow. Basically, they just don't give a damn about what the humans are doing. They rarely gave me the time of day for a photo, so when this dude propped up and presented himself, I felt privileged.  They have been known to dive up to 750m and for around 70 minutes. Most of their dives are around 50 - 500m and 15 - 20 min. long. They eat like most other seals, fish, crustaceans and those cephalopods. See also Leopard Seals . Antarctic Fur Seals and Elephant Seals
Weddell Seal - Davis Station
Weddell Seal - Davis Station
Weddell Seal - Davis Station
Weddell Seal - Davis Station

Tuesday, February 15, 2011

Antarctic Wildlife - Leopard Seals

Leopard Seal - Near Peterson Island 2011
Scientific name: Hydrurga leptonyx

Physical description and related species

The leopard seal is easily identified: designed for speed, the body is slender and the foreflippers long. The head is large and the jaws open widely revealing exceptionally long canines and unusually complex sharply pointed molars. Like the crabeater seals, leopard seals have unusual teeth for straining krill from the water.
Males (2.8 m; 320 kg) are generally slightly smaller than females (3.0 m; 370 kg). Large females may reach lengths in excess of 3.5 m and weigh over 500 kg.
Leopard seals may live for 26 years or more.

Distribution and abundance

Leopard Seals are solitary animals that inhabit pack-ice surrounding the Antarctic continent. They are perhaps the greatest wanderers of the Antarctic seals with sightings in Tasmania and a northern record at Heron Island. Heron Island is located at 23 degrees 27 minutes South—quite some distance from the Antarctic!
They may occur year-round on some subantarctic islands including the Australian territory of Heard Island. In the winter months, young leopard seals from the south visit Macquarie Island.
The population may be as large as 222 000 individuals.
Threats: The only natural predator of leopard seals is the killer whale, though an observation of a male elephant seal having killed a leopard seal while ashore at Heard Island has been reported. This is likely to be an uncommon occurrence.
The Australian Antarctic Division is interested in the factors that drive the cyclic nature of the occurrence of leopard seals at Macquarie Island and further to Tasmania. Studies of the movements of the seals within the pack-ice zone are also undertaken.
Conservation status: least concern


Because leopard seals are solitary animals that live in the Antarctic pack ice, little is known of their biology. Female leopard seals of six years or more give birth to a single pup on the sea-ice in November after a nine month gestation, and then return to the ocean to feed. The pup may weigh in excess of 30 kg.

Diet and feeding

Leopard seals eat almost anything, including penguins, fish, squid, crustaceans and other seals. Seals eaten include seal pups of crabeater, Weddell and fur seals. One animal, captured near Sydney, had eaten a full grown platypus.
The feeding behaviour of leopard seals is easily seen when their prey is a penguin. Typically the seals chase or grab penguins in the water and thrash the captured bird back and forth until the skin peels away. The remaining carcass is then consumed.
Leopard seals have very individual tastes. Some remain near penguin colonies and eat the penguins they catch there while others prefer to eat crabeater seal pups. Other leopard seals prefer a subantarctic menu and migrate north to Heard Island to feed on penguin and seal pups there.
One could be forgiven for thinking that this seal looked a little like a lizard.  While on the land the penguins don't seem to worry about these big sods, but in the water the leopard will catch and kill the birds by skinning. They virtually turn them inside out by banging the carcass on the water. We have seen the remains on occasion which looks like a penguin glove. They can act aggressively towards boats and occupants, but as a rule they don't actually attack humans. Thank god for that. Don't think I'd enjoy been turned inside out and made into a glove...!

Sunday, February 13, 2011

Antarctic Wildlife - Emperor Penguins

These Emperor penguins aren't seen much around Casey, so when three of them just walked and tobogganed past us it was a treat. We also spotted them on an ice flow weeks latter. But you seem to always remember the first time for anything. Anyway, these big buggers are the biggest of all the 17 species of penguin. They grow up to between 1.0 and 1.3m in height and weight in around 20 - 41 kg. They eat mainly fish and crustaceans and cephalopods. You know crab and squid and octopus type thingies captured during pursuit diving. They can dive for 15 - 20 minutes at a time and to depths of 50m. They have been recorded to dive at depths of 250m also. Like the Adelie penguins they are very social characters and can be found in very large colonies of over 200000 pairs. They are monogamous, but usually do not renew their bond the following season. On a personal note, they are very regal  and proud looking birds. They are probably not as inquisitive about human activities as the little Adelie, but that may well be my own lack of experience with them.

for more penguin pics of mine go to my facebook album

or a later blog on emperors at Amanda Bay video 
 or Some more emperors

Antarctic Wildlife - Adelie Penguins

This little fella is incredibly sociable. This includes being very curious about human activities. They will wonder straight through Casey station without fear of our activities and will come right up to you if you remain still. Of course feeding or touching them is a strict no no. I was welding a new bollard at the Casey wharf one day prior to our resupply, when I raised my welding helmet, there was one of these little guys standing about 3 to four metres away. Hell I hope he didn't get a weld flash. Anyway, these guys are true Antarctic penguins. They are monogamous and have an accelerated breeding cycle. They eat mostly crustaceans, with some fish Krill is also favoured in some locations. Most food is found 20 to 40m below the surface, but have been recorded as diving as far down as 175m.  Their colonies are usually large,  noisy, and they pong (smell bad). Some of the colonies around Casey have around 30 to 40 thousand penguins in them. They are not considered at this time to be endangered. They range in height from 70 to 71 cm tall and have a weight range from 3.8 - 8.2 kg.  Leopard seals love to eat 'em. From what I have observed, they have strict paths of travel that they travel by when in a group and  when on land. When you disrupt that path with say, a fuel line or a track pushed through the snow, they will walk up and down that obstacle until they can regain the original path. They may also just stand there in a big huddle at the obstacle obviously discussing what the hell is this thing doing on our pathway. Then, one brave soul will jump over, lets say a fuel line (75mm in diameter), and then the rest of the cowards will follow. This may take hours, with committee meetings and sub committees obviously considering all impacts that such a crossing will have on their survival...!

for more pics on penguins go to my online store

Check out mu Utube video on the Adelie as well.

See Also Emperior Penguins