November 6, 1996

Doug Quin's tent at Big Razorback Island.

The weather broke during the night and I woke up at 5:30 with the sun slanting through a part in the curtains; Jim was still asleep. I walked to the lounge next door and checked the video monitor "scroll" for the daily forecast and flight schedules. Things were back on track and it was going to be a busy day of flying--with the delays, the schedule for Pole was running behind. Out the window of the dormitory, the light shimmered off the Royal Society Mountains. The plan for the day was to begin censusing the Weddell seal groups in a study area that covers Scott Base up to Cape Evans on this side of the sound. As part of a longitudinal study of population dynamics developed by Don Siniff nearly 30 years ago, the starting time for the census has always been on, or about, November 5.

When I showed up at Crary, Don had already gone to gas up the Spryte, which we would take out to camp. Tom and Mike teamed up and Dan and Rob also joined forces for their count from snowmobiles. After a quick stop at the Berg Field Center to pick up my field gear and a Scott polar tent, Don and I made for the sea ice. A lone male seal rested on the ice near the snowmobile area--isolated and apparently chased away by other, more dominant males. The road out the sea ice runway was busy with vehicles and personnel--making up for lost time. It was nice to see the horizon again after a few days of whiteness; Black Island and Mt. Discovery measured the distance across the sound.

Several inches of powdery snow had fallen over the last several days. As we moved past the Erebus ice tongue, whose blues were irridescent, the wind picked up. In the distance, Tent Island seemed to hover over the sea ice; the wind blew snow in a dense sweep about 50 feet high. Occasional eddies would rise like dust devils and disappear. The surface held reticulated patterns and myriad finely tapered drifts, some no more than half an inch wide and a few inches long; these indicated the prevailing wind direction. Snow snakes wound along the ice. The horizon features became obscured. It was a few minutes before nine o'clock, when Don stopped, "We are going to have to rethink this."

Tom and Mike had raced passed us on snowmobiles, and were heading for camp. Dan and Rob had already left in the opposite direction from MacTown to begin their count near Scott Base. Don got on the radio and, after a discussion with Tom, canceled the census for the day. The surface conditions were just not good enough to be able to discern seals. Dan and Rob could not be reached and concern was expressed that they had already launched their counting operation. We arrived at

Don, Tom, Mike and I off loaded the gear from the Spryte. I surveyed the network of tidal cracks off Big Razorback and looked at the groups of Weddells; two gatherings were concentrated at either end of the island. A few more mothers and pups were scattered in between. They had been at the surface for a while, as the snow formed a thick crust on their fur. The pups were a honey coloured brown. The surrounding ice was stained with blood and urine and skuas strained at placentas, half-buried in the ice. Their gull-like calls and the pleading of the pups reverberated off the face of Big Razorback, which arcs slightly to produce a parabolic shape--focusing sound in the leeward shelter. Scree loosened and fell to the ice. I wanted to situate my tent so that I could set up my hydrophones for recording in a parallel relationship to the cracks. In this way, I could listen to the passing parade of Weddells, as they surfaced for air.

With Mike's help, I dug down to the sea ice through about 2 feet of snow and cleared the surface for pitching my Scott polar tent. We then paced out two sites, about 160 feet apart, and proceeded to drill three 12 inch holes in the ice for lowering my hydrophones: one of which would be located in my tent. This first hole was drilled slightly below sea level and, when we broke through at about 6 feet, it gushed and flooded my floor! As the sea water froze it helped level the array of cracks that had developed over the winter. I was relieved that I had not yet pitched the tent.

Big Razorback Island	Skua
Drilling hydrophone channel in the sea ice.

With the holes drilled, Don and Tom suggested that we tag and put a radio transmitter on a male Weddell, which Mike had seen earlier. We would also be obtaining a blood sample, as part of the DNA and paternity study that Tom has undertaken. At this time of year, the only seals at the surface are generally mothers and their new young; males are not that common. Dominant or successfully breeding males spend most of their time in the water defending their breathing holes in the ice. Mike and Tom assembled kits with the necessary equipment and put them on a snowmobile. Don and I walked ahead to where the male had been spotted. He was sunning himself at the base of the precipitous slope of Big Razorback.

On our approach, he moaned and hissed, rocking on his side. I was designated as the flagger and had a green flag on a bamboo stick with which to distract his attention. Mike walked around to approach the seal from behind with a black bag which resembled a sea anchor, complete with two heavy duty ropes. In a quick maneuver, he tossed the bag over the seal's head and reined in the ropes behind the flippers. "It rarely goes this easily!" The bag over the head generally has a calming effect on an animal. It is a much better alternative to drugging the animals--a practice which has long been discontinued with Weddells. This one struggled and bucked a bit before becoming still. Mike looked like a rodeo rider and the "bronco" urinated on his leg. He had already been tagged, as it turned out. The tag was hard to see on the tail flippers. Don took a blood sample from a spot on the lower back and then he, Don and Tom set about placing a small radio transmitter on the back. The transmitter is about the size of a "C" cell battery, embedded in resin and mounted on a mesh patch. The seal's fur was gently pulled through the mesh and the whole rig is glued with an epoxy resin in place. No sooner than it was in position, the animal bolted; Mike grabbed the reins and was taken for a ride. The hood came away and the seal headed for his hole in the ice. We all tried to distract him, so the epoxy could set. No luck, this guy was determined and he slipped into the tidal crack slush.

The transmitter sends a signal back to a receiver and data recorder at camp. It is one of 8, attached to different males. The signal can only be received from the surface and not from underwater. What Tom is trying to figure out is how much time males spend in the water, how much time on the ice. Each transmitter is assigned a specific frequency, so Tom knows which animal is on the ice at any given time. The data recorder logs in the frequency, time of day of each surface visit.

"Bagging" a seal to place transmitter.

Placing a transmitter on the back of a Weddell seal.

As we wrapped up, Dan and Rob showed up. They had, in fact, done their count; it had been a long day. Together, we tagged another male and a pup before returning to camp. I was anxious to get my tent set up, before the chill of the evening set in. Mike and Rob lent a hand and within an hour and a half, all the ropes and ice screws were set. Pitching a tent on sea ice in such a way as to withstand 70 mile per hour winds is no small feat; I was grateful for their assistance and good natured attitude. From my tent, I had a great view...

The tent space was cramped, or rather, intimate--about 6 feet by 6 feet. Thankfully, I could stand up within the pyramid shape. Furthermore, I could just fit a folding cot in to one side--it was nice to not sleep on the ice. I arranged my recording gear, and looked down the "fishing hole" where I would drop my hydrophone. The Scott tent is yellow and, with the filtered sunlight, the icy water is aquamarine and intensely blue. I cleared the plate ice skin and peered into the darkness below. Although I was less than 200 feet from Big Razorback, the water I was told is several hundred feet deep.

A tent with a view.

"Fishing hole" for hydrophone.

Before dinner, I wanted to have a quick listen and see what could be heard, so I set up a digital audio tape recorder (DAT recorder) and connected a hydrophone, which I lowered carefully to a depth of 50 feet. Sure enough, the Weddell seals were vocalizing! What an extraordinary range of sounds they produce. I had spoken with Jeanette Thomas, a former student of Don's whose pioneering work in Weddell vocal behaviour was extremely helpful to me in my preparations. She has classified and described 12 types of calls, with 34 discrete phrases.

To me, the ocean seemed to be an infinite realm of soundings: chirps, squeaks, booming territorial pulses, long, thin glissandi of complex tones that whispered like radio frequencies at night, a sharply rising pure tone that would abruptly end. In the mix there were creaking sounds and the occasional ping of tension being released as the ice adjusted at ebb tide. After dinner, a delicious feast of shrimp and pasta with a liberal flow of wine, I headed for my tent. Setting up a pair of hydrophones to a depth of 60 feet gave me a beautiful stereo image; I lay in my tent recording until 3:00am listening to one of the most remarkable musical performances I have ever heard. It was hard to sleep and I was up in a few hours to record again. To hear a few samples of these wonderful sounds, please select from the examples below:

Weddell Seal Vocal Sample #1

Weddell Seal Vocal Sample #2

Technical note...

I have been doing wildlife recording for more than 10 years, and I have rarely had the kind of experience that I had recording Weddell seals. In addition to being in the right place at the right time, I was particularly grateful for having the benefit of reliable and durable equipment--particularly hydrophones from International Transducer Corporation. The ITC 6050 hydrophones are truly fantastic instruments! I brought two of them with me; I wanted to see how they might work in tandem and was curious to hear what sort of two channel, or stereo, image might be possible using a pair of omnidirectional hydrophones. The recordings of Weddell seals on track #3 of the "Antarctica" CD and the Weddell seals, leopard seals and orcas on track #7 of the CD were made under the sea ice of McMurdo Sound using the pair. The 6050s performed beautifully in some pretty extreme conditions. On more than one occasion I made my recordings in a tent on the sea ice, where the temperature would often fall well below -30F. The water temperature was between 29F and 32F degrees most of the time. Rather than coiling wet, freezing cable in a howling wind after every session, I left the 6050s out for days at a time--chopping out ice regularly so that I would not lose them.

The recordings were made to a Sony D-10 Pro II DAT machine. Between the low-noise on the 6050s, an absence of wave action under the ice and a lowered noise floor in the 24 bit remastering of the CD, the recordings are pretty clean and quiet. The "tinkling" and "snapping" sounds that you hear on the two cuts are ice crystals breaking from the underside of the sea ice. There is a gentle tidal pull that breaks newly formed ice. The deeper "pinging" and "booming" are actually ice fractures. You can hear more of this in track #7, were I was right at the ice edge--perhaps 50 feet away. The ice was only a few feet thick.