Macquarie Island Adventure: Orca encounter

Hi,
Welcome back after the Christmas and New Year break. It has been an amazing few weeks here on Macquarie Island.

One of the many spectacular sights on the island is that of a killer whale (Orincus orca), commonly know as an orca.

Just a couple of days ago I was on field trip (another story) with Clive (the doctor). We were walking back to station from Brothers Point hut, where we had spent the night. We walked along the east coast, sometimes on a grey/black sandy beach, then at other times over larger rocks and pebbles. Some parts of the route along the east coast are along some very rugged coast, usually the extension of a ridge off the escarpment right up to the waters edge.

It was as we were scrambling over some large boulders that we happened to glance out to sea. About 50 metres offshore a large dorsal fin broke through the crystal clear water.

Large male orca seen off the east coast on Monday the 7th of January 2014

We stopped and I took my camera out of my jacket, where I had kept it covered from the light drizzle. The fin broke through the surface again, just north of its previous position, so I quickly zoomed in, focused and took the photo.

It broke the surface another two times, when it must have taken a deeper breath because we did not see him again. We also noticed another fin much further out.

We have seen many orcas in Buckles Bay and elsewhere around the island. They usually travel in groups, searching for food.

The killer whales live in complex society groups based on matrilines consisting of a matriarch and her descendants, which form part of the line as do their descendants. The average size of one of these groups is 5.5.

The males in the group will link up with other matrilineal groups to mate.

On December the 12th (2013) the call went out that there were orcas in Garden Cove. Everyone that was around station grabbed there cameras and warm clothing and headed up to the Ham Shack to get a better view.

There were 6 orcas in and around the waters of Garden Cove and we were treated to a spectacular display of social interaction including the hunting of prey.

12 Dec 2013 - two of the orcas in Garden Cove (Barend Becker)

Individual orcas can be identified by a combination of distinctive body patterns, dorsal fin shape and obvious scars. They are largest of the oceanic dolphin family. The males dorsal fin is typically 1.8m tall (5.9ft) and is twice the size of the female's and in the shape of a triangle. The female dorsal fin is shorter and more curved.

12 Dec 2013 - Large male near the rocks - note the notches in it's dorsal fin (Kris Carlyon)

12 Dec 2013 - The same male as above reflecting the setting sun (Lionel Whitehorn)

The males range from 6 to 8 metres (20 to 26 ft) in length and weigh in excess of 6 tonnes. The female are typically 5 to 7 metres (16 to 23 ft) in length and weigh 3 to 4 tonnes. Calves at birth weigh about 180 kg (400 lbs) and are 2.4 metres long (7.9 ft). Pace these lengths in your lounge or hallway to get a better appreciation of their size.

Comparative size of orca to a human

12 Dec 2013 - Large male cruising past the rocks below the Ham Shack (Barend Becker)

Females mature at about 15 years of age, giving birth to a single calf every 5 years until they stop breeding at the age of 40. The lifespan of a female is around 50 years, though they can live up to the age of 80 - 90.

The mortality rate of calves is very high with up to 50% of them dying in the first 6 to 7 months. They are weaned at 2 years and both male and female adults take care of the young.

12 Dec 2013 - Close up of female expelling a breath (Kris Carlyon)

12 Dec 2013 - Female cruising past in the crystal clear water - possibly the same as the one above (Lionel Whitehorn)

It is estimated that there are around 25,000 killer whales in the Antarctic region, which is about half of the minimum population around the world. Their are many sightings of killer whales around Macquarie Island, but it is not known how many whales range around the island. TASPWS has asked all of the expeditioners on the island to keep a lookout, and if possible take pictures.

12 Dec 2013 - female orca breathing out (Lionel Whitehorn)

12 Dec 2013 - orca just below the waters surface (Barend Becker)

Killer whales are apex predators, meaning they themselves have no natural predators. Their prey varies according to the environment they are in. On average a killer whale eats around 227 kg (500 lbs) a day.

Over the last few months (Late Spring, early Summer), there is a abundance of seal pups. It is around this time that the elephant seal pups have weaned and are entering the water for the first time.

It is thought that of the thousands of pups born on the island about 50% don't survive the first year.

Killer whales also prey on the abundant penguins.

The following 2 images are of a killer whale chasing a elephant seal weaner.

12 Dec 2013 - A killer whale makes a sharp turn in pursuit of its prey (Kris Carlyon)

12 Dec 2013 - the lucky seal (on the left) makes its escape (Kris Carlyon)

Often, to avoid injury, a killer whale will disable their prey before killing it and eating it. This may involve throwing it in the air, slapping it with their tails, ramming it, or breaching and landing on it.

12 Dec 2013 - a female, probably the matriarch, with a elephant seal weaner in its jaw (Lionel Whitehorn)

12 Dec 2013 - same as above, with the larger male killer whale swimming alongside (Kris Carlyon)

12 Dec 2013 - female orca in the foreground dragging a weaner, while the large male follows (Barend Becker)

12 Dec 2013 - female orca swimming south with the glint of the setting sun on its dorsal fin (Barend Becker)

In September I was fortunate to be on an a boating trip that took us to Hurd Point and around the southern part of the island to Caroline Cove on the west coast. This was the subject of another post - A Perfect Day for Boating

On the way back up the east coast, in almost perfect conditions we encountered a single large male orca, who seemed to be slowly cruising north. The following images are from that day.

Sep 2013 - large male orca just south of Lusitania Bay (Barend Becker)

Sep 2013 - a close up of the same male orca - note the distinguishing scar on the top of its head (Barend Becker)

In one of the boats the coxswain Greg had a camera underwater and took some amazing video of this orca. The following is a still taken from this footage.

Sep 2013 - underwater still of the orca from a short video (Greg Bird)

December 12th must be a special day for orcas in Garden Cove. Kris the ranger discovered that on the same day in 2012 there was a group of orcas in the cove, feeding on elephant seal weaners.

12 Dec 2012 - maybe the same family group of orcas feeding in Garden Cove (Photographer unknown)

In the last week of December another boating trip was organised. My work colleague Vicki was fortunate enough to be on board. In flat clam conditions they encountered a group of orcas near the Nuggets. Vicki managed to take some spectacular images - shown below.

27th Dec 2013 - orca and royal penguin swimming north (Vicki Heinrich)

27th Dec 2013 orca with royal penguin swimming alongside (Vicki Heinrich)

In early November we have also had the pleasure of a visit by a southern right whale in Garden Cove. Again the call went out an we all went up to the Ham Shack to get a better view. It was cruising slowly in the kelp. Kris (TASPWS ranger) suggested that it was trying to clean the barnacles on its skin.

This whale can grow to a length of 15 metres (47 ft) and weigh up to 47 tonnes. It is listed as "endangered".

Interesting fact - the testicles of the southern right whale are likely to be the largest of any animal - each weighing 500 kg (1,100 lbs).