Ice Stories: Dispatches From Polar Scientists » skuas http://icestories.exploratorium.edu/dispatches Mon, 15 Nov 2010 20:40:36 +0000 http://wordpress.org/?v=2.9.2 en hourly 1 The Scene Outside: Lots of birds http://icestories.exploratorium.edu/dispatches/the-scene-outside-lots-of-birds/ http://icestories.exploratorium.edu/dispatches/the-scene-outside-lots-of-birds/#comments Thu, 11 Feb 2010 01:06:29 +0000 Rob Dunbar http://icestories.exploratorium.edu/dispatches/?p=2228 JOIDES RESOLUTION, OFF THE COAST OF WILKES LAND, ANTARCTICA– Our ship is constantly surrounded by Albatrosses, Petrels, and Skuas. Sometimes we see more than 100 birds surrounding the ship. They swoop and dive, looking for food in the water...]]> Temperature 0°C, wind 30 kts, 6 meter swells

At Site U1359, Hole U1359B,
Position: 64º 54.25’S, 143º 57.63’E
Water Depth: 3100 meters

ABOARD THE JOIDES RESOLUTION, OFF THE COAST OF WILKES LAND, ANTARCTICA– Hi everyone! As we approach our 2000th meter of drilling I thought I would change things up a bit with this blog and send along some photos of the birds we’ve been seeing. The Southern Ocean is the coldest and windiest on Earth, but it also one of the most bountiful. During the 3 or 4 months of long days and short nights, the “farm” operates 24/7. The plants that live in the sunlit waters here are nourished by nutrients that mix upwards from the deep sea and go into overdrive building their cells. It’s easier for nutrients to mix upwards into the sunlit upper waters here simply because the water column is “isothermal”. This means that we see very little variation in the temperature of the sea between the surface and the bottom waters over 3000 meters below us. It is all close to 0 degrees Celsius. This means that it takes very little energy to move dense cold water from the deep upwards because the surface water is also cold and is almost as dense. So the plants have everything they need. The wind and circulation drive the mixing, which brings in the nutrients, and the sun keeps the farm growing nearly 24 hours every day. Plants (mostly single-celled protists called diatoms) grow fast and the small plankton that eat the diatoms grow fast as well. Which brings us to the birds…..


Albatrosses in a storm.

Our ship is constantly surrounded by Albatrosses, Petrels, and Skuas. Sometimes we see more than 100 birds surrounding the ship. They swoop and dive, looking for food in the water, either plankton or small fish, or perhaps they think we are land. We haven’t seen one try to rest on the ship yet. In fact the Albatrosses rarely set down at any time. They fly 1000’s of miles from their breeding colonies and are at sea for months and even years at a time.

Here are some photos of the seabirds we’ve seen so far.

These first two are of Black-browed Albatrosses (Thalassarche melanophrys). They live throughout the Southern Ocean and breed in places like the Falkland Islands and South Georgia. They can live to be as old as 70 years and spend long periods of time at sea, even encircling the globe. They feed on krill and small fish – that in turn eat diatoms and smaller plankton.


Black Browed Albatross

Black Browed Albatross

The most common bird we saw at our drill sites close to the Antarctic continent were the Pintados, also known as Cape Petrels (Daption capense capense). The name Pintado comes from the Spanish word for “painted”. They live throughout the Southern Ocean, mainly eating krill, especially on and near the continental shelf of Antarctica in summer. A 2009 census estimates there are over 2 million Cape Petrels alive today.


Cape Petrel (Pintado)

Cape Petrel (Pintado)

Cape Petrel (Pintado)

We’ve also been surrounded the past few days by Southern Giant Petrels (Macronectes giganteus). These are indeed big birds….females can weigh up to 18 pounds. Sometimes they are called “stinkers” as they can spit a foul-smelling liquid at predators or when they are perturbed.


Southern Giant Petrel

Southern Giant Petrel

I hope you enjoy these photos! I’ll get back to our science and progress next time and I’ll try to knock out least one more video blog. We are VERY busy with work here now but it all very exciting.

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Penguins 1 – Skuas 0 http://icestories.exploratorium.edu/dispatches/penguins-1-skuas-0/ http://icestories.exploratorium.edu/dispatches/penguins-1-skuas-0/#comments Wed, 23 Dec 2009 18:22:30 +0000 Jean Pennycook http://icestories.exploratorium.edu/dispatches/?p=2046 CAPE ROYDS, ROSS ISLAND, ANTARCTICA– When Adélie Penguins adapted to live in the harsh environment of Antarctic they pretty much got this place to themselves. Nesting on the ground in other parts of the world is very risky for birds as this makes them extremely vulnerable to the numerous predators. In Antarctica there are not as many predators, but the one that discovered eating is easy in an Adélie penguin colony is the South Polar Skua.


South Polar Skua.

This large aggressive bird is an opportunist. When the seals haul out on the ice and give birth to their pups the Skuas hang around and eat the after birth. At McMurdo Research station they will wait for people to leave the dining hall with a sandwich or cookie in their hand and swoop down for the ‘kill.’ When it’s time for them to breed many build their nests at the edge of penguin colonies where first the penguin eggs then the chicks can be easy pickings among the penguin parents who are just beginning.


Skuas, tag teaming a penguin to get the egg.

Adult Adélie Penguins can defend themselves so are safe from Skua attack. However, while the penguins are nesting, and before the Skuas lay their own eggs, the Skuas work in pairs, one will fly overhead to distract the Adélie and the other will swoop in and snatch the egg or chick as the penguin stretches to peck at the decoy. Often times when I’ve been sitting watching this, I wish that the penguins would someday take revenge.

The Skuas often build their nest close to the Adélie breeding colony so they do not have to go far for their food. But in the following sets of pictures you can see this Skua was very bold, laying the egg within 10 feet of nesting Adélies. At first the Adélies would walk by with only passing interest in the nesting Skua but finally one penguin decided this was too close and challenged the Skua.


A Skua nest very close to a group of Adélie Penguins.

Some penguins would walk by without paying attention to the intruder.

First a challenge.

Then the Skua is evicted from the nest.

Every attempt by the Skua to return to its nest was thwarted by the penguin.

Finally the egg was lost to other Skuas.

Skuas are no match for adult Adélie penguins so the Skua moved off the egg. The penguin did not chase the Skua but stood at the nest and did not allow the Skua to return. Every attempt by the Skua to return to the egg was thwarted, and meanwhile the Skua egg was getting colder by the minute.

Skuas are indeed opportunist eaters. Even exposed Skua eggs are taken. This egg was no exception and once the penguin walked off, with in a few minutes another Skua made this egg its meal. The Skuas abandoned this nest site and will likely build one a much safer distance away next time. Penguins 1 – Skua 0.

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Dry Valleys: Looking for Life on Mars http://icestories.exploratorium.edu/dispatches/dry-valleys-looking-for-life-on-mars/ http://icestories.exploratorium.edu/dispatches/dry-valleys-looking-for-life-on-mars/#comments Fri, 02 Jan 2009 18:26:10 +0000 Mary Miller http://icestories.exploratorium.edu/dispatches/?p=1474 LAKE HOARE, DRY VALLEYS, ANTARCTICA– After spending time at the South Pole, flying to Cape Royds and Black Island, and otherwise keeping ourselves busy with webcasts and scientist interviews in McMurdo, Lisa and I hopped on a helicopter out to the Dry Valleys for a couple of days of hiking and camping in the coldest, driest desert on Earth. Our base was the Lake Hoare field camp nestled next to the Canada Glacier.


Canada Glacier with frozen Lake Hoare in the background.

Summer melting from the Canada Glacier feeds a stream that flows into Lake Hoare.

The Dry Valleys are dry because very little snow falls here, the average water content is less than a centimeter. Yet a fully functioning ecosystem exists here, in the ice-covered lakes and the soils of the valley floor. Even though the ecosystem is all but invisible to the naked eye, it still has a basic food web: primary producers (mats of moss and algae in the lakes, bacteria, yeast, fungi and other microbial life in the soils ), grazers (microscopic invertebrates called rotifers and tardigrades), with the top of the food chain consisting of tiny nematode worms. Curiously, there are no known predators in the Dry Valleys soils. These valleys constitute a Long-Range Ecological Research (LTER) study site and represent what scientists believe might be a model for life on Mars if it exists.


Lisa Strong on a hike with Canada Glacier behind her.

The origins of Seuss Glacier pouring through a mountain pass in the Dry Valleys.

Lisa and I went for a walk up the Taylor Valley to see whether we could uncover any evidence of life and saw little, except for a couple of long-dead seal mummies (why they traveled so far from the sea ice is anyone’s guess) and some algae-covered rocks and brown floating scum, looking for all the world like whipped chocolate mousse. We did see plenty of wind-scoured rocks and glaciers pouring through gaps in the surrounding mountains.


Bones and skin of a seal mummy that perished hundreds or thousands of years ago.

Biological scum on Lake Chad.

For easier walking, I tried to cross the moat between land and solid (white) lake ice. What I thought was thick ice wasn’t and I broke through up to my knees for my own version of the polar plunge. After changing into dry pants and socks, we continued on our walk but the only macroscopic life we saw was a lone skua winging up the valley.


Mary after breaking through lake ice.

I knew I needed to dig deeper, so I’ll turn to the LTER scientists studying the different parts of this ecosystem from the glaciers that feed life-giving water to the lakes and soils, to the ice-covered lake waters that support microbial life, to the soils that provide habitat to bacteria, yeast and fungi, and invertebrate creatures that make up “charasmatic megafauna” of the Dry Valleys. Look for upcoming video interviews with these LTER scientists.


Glaciologist Hassan Basagic of Portland State University explaining the dynamic of Canada Glacier to Lisa.
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Royds Tranquility http://icestories.exploratorium.edu/dispatches/royds-tranquility/ http://icestories.exploratorium.edu/dispatches/royds-tranquility/#comments Fri, 12 Dec 2008 23:00:52 +0000 David Ainley http://icestories.exploratorium.edu/dispatches/?p=1320 CAPE ROYDS, ROSS ISLAND, ANTARCTICA– First time this has happened, but I was sitting today for a spell just to watch the penguins here at Cape Royds and the only sound was that of the blood going through my ears. Not a sound was coming from the 2000 or so penguins arrayed before me. Then I heard a skua call, and then a penguin sneezed. These penguins are “zoned”! or Zened! This is quite the opposite of the chaos I found at Beaufort Island, the subject of my last report. What a contrast!


A tranquil scene at Cape Royds: penguins quietly sitting on eggs, dreaming of food, 65 km away. But, tranquility sometimes can be deceptive. Kind of like the Western Movie where one guy says, “Its quiet out there, isn’t it?” And Tex says, “Yes, too quiet!” Then a big shooting battle starts.

The colony has certainly been quiet, with very few birds coming in or going out to sea. In my first dispatch of the season (“The Early Returns”) I detailed the fast ice situation: a continual sheet of ice out to beyond the horizon. Its edge at the open water is about 60 km away now; at the beginning of the season it was at 75 km. Walking about 2-3 km/hour that distance adds 30 hours to a trip, not counting times for resting or checking that there are no leopard seals at any wide cracks along the way. I can recall seeing 3 cracks on trips that we’ve flown out to Beaufort. Penguins can wait at these for hours to make sure nothing nasty lurks in those black waters in the channel between the white ice.

The penguin pairs are well coordinated in their schedules but there is very little cushion for major delays. Adding a day or two to a trip can spell disaster to the bird on the nest who is dreaming of a fish or krill dinner. Well, it’s a disaster for both members of the pair! In fact, this season has been a disaster so far for many. I’ve been keeping track of 38 nests of banded, known-age birds since early Nov. As of today (12 Dec), 55% of nests in which eggs were laid have failed. Each nest started with one or two eggs, plus of course the incubating bird. Such a loss rate means that lots of birds incubating the eggs waited way past comfort…stomach growling…and finally had to leave. Males are prepared to sit for two weeks or a bit more while taking the first turn at incubation. They can lose 30% of their body weight or more awaiting their mate to return.


Here is a penguin that can not wait a minute longer. He has been staunchly taking care of these eggs for 3 weeks, and now it is time to eat. His mate is no where to be seen, but he’s got to go. That’s the way it’s been so far this season, males taking very long first responsibility on the nest while the females search for food in order to be able to sit for weeks when she arrives back.

Sometimes skuas can intimidate penguins to leave. The skuas just sit there staring at the penguin for hours, just out of pecking range. The penguin can’t take it any more. Or, sometimes one skua pesters the penguin by pulling its tail, and then the other grabs the egg when the penguin reaches back to peck the tail-pulling skua.

A few weeks ago there would have been 25 nests in the foreground of this view. Now there are 13 and all are vulnerable to skua staring as there is space free of penguins around every nest. Neighbors are needed to guard one another’s flanks.

A fine meal for a skua, offered by a penguin who had to go in search for its own food.

You can see the result of many birds having given up: broken eggs everywhere. This is quite different from Beaufort (see last dispatch). These nests didn’t roll out of poorly built nests…just look at all the rocks in these nests. These eggs were left by the penguins, and the skuas then arrived to eat them.

Well, so, things are looking kind of bleak at Royds this season, certainly a stark contrast to the ‘happy’ chaos of the Beaufort Island colony and a stark contrast to last season at Royds!!! Many, many 10’s of thousands of chicks will be produced there at Beaufort, in spite of the seeming chaos. What’s with this global climate change? They said it should be getting windier in these parts, and the wind would blow the ice away. I think they also said the weather would be getting more unpredictable and more wildly varying. I guess they got that part right! Kind of sad, though. Gotten rid of your gas guzzler yet?

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