elular, and Bahia Crossley) with the greatestdepth reached being 9.5 meters at Bahia Crossley.

pollen analysis is being carried out by RalphT'aggart, Michigan State University, which willhopefully shed new light on the post-Pleistocene

Zmatic and vegetational history of the Fuegianion. A paper on the vegetation of Isla de los

Estados, past and present, is in preparation by Dr.Taggart and me.

The success of Hero cruise 71-5 is due in no smallpart to the dedicated support of Captain Libertyand his crew. Gratitude also is expressed to Dr.H. A. Imshaug, chief scientist of the expedition.I thank Drs. D. M. Moore, Imshaug, and Dudley,and Mrs. Goodall for their critical review of mymanuscript.

References

Bridges, E. L. 1948. Uttermost Part of the Earth. London, Hodderand Stoughten.

Crow, G. E. 1974. A revision of the North American speciesof Sagina (Caryophyllaceae). Ph.D. dissertation, MichiganState University, East Lansing.

Imshaug, H. A. 1972. R/V Hero cruise 71-5 to Isla de losEstados. Antarctic Journal of the U.S., VII(2): 42-44.

Mitterling. P. I. 1959. America in the Antarctic to 1840. Urbana,University of Illinois Press.

Skottsberg, Carl. 1909. Pflanzenphysiognomische Beobachtun-gen aus dem Feuerlande. Schwedische Sudpolar-Expedition,1901-1903, IV(9): 1-63.

Skottsberg, Carl. 1910. Ubersicht über die wichtigsten Pflanzen-formationen Südamerikas S. von 41°, ihre GeographischeVerbreitung und Beziehungen zum Klima. Svensk. Vet. Akad.Handl., 46(3).

Young, S. B. 1973. Subantarctic rain forest of Magellanic Chile:distribution, composition, and age and growth rate studiesof common forest trees. Antarctic Research Series, 20: 307-322.

Encounters with leopard seals (Hydruga leptonyx)along the Antarctic Peninsula

T. F. DELACA, J . H. Lipps, and G. S. ZUMWALTDepartment of Geology

University of Calfornia, DavisDavis, California 95616

The leopard seal, Hydruga leptonyx, is a majorlarge carnivore in antarctic waters that frequentlyconsumes warm-blooded prey. It is commonlyabundant in nearshore areas or along edges of packice where it feeds chiefly on krill, penguins, andsometimes other pinnipeds. It has a rather sinisterreputation among some antarctic explorers,probably because of its reptilian appearance,toothy maw, and predatory behavior. Knownattacks or possible aggression toward humans,however, are few and are anecdotal in nature. Thisseal nevertheless is potentially dangerous becauseof its large size, mobility, and feeding habits.

For the past 4 years our group has engaged inscuba diving and small boat operations chiefly atPalmer Station (Anvers Island), as well as atnumerous other locations along the AntarcticPeninsula. Well over 1,200 dives and hundredsof hours of small boat operations have been com-pleted, during which there have been several en-counters with leopard seals that have caused usconcern. We have documented our experiencesand observations because they appear to be largelyunrecorded and unique, and because these sealsmust be regard .-d as dangerous to humans in or

near the water. In addition to summarizing ourencounters, this paper presents the proceduresthat we have developed to avoid or to reduce thehazards of coping with leopard seals.

"Although krill are commonly taken,leopard seals consume larger prey as

well. . ."

Predatory behavior

Previous observations of leopard seal predatorybehavior primarily have been made near penguinrookeries and around floating ice (Hofman, in

May/June 1975 85

press; Müller-Schwarze, 1971; Penney and Lowry,1967; Ray, 1966). The type of food taken and thebehavior required to capture it are dictated by thefood's availability and by shifts in emphases offood preference that occur as the seal ages (Hof-man, in press). Although krill are commonly taken,leopard seals consume larger prey as well: forexample, penguin adults and chicks as they enteror leave the water (MUIler-Schwarze, 1971; Penneyand Lowry, 1967; Peterson, 1965), fish (Ray, 1966;Hamilton, 1934), platypus (Scheffer, 1958), andother species of seals (Hofman, in press) includingan adult sea lion (Hamilton, 1934). Leopard sealsnormally do not hunt on land or ice; prospectivevictims therefore are relatively safe there. We haveseen penguins being pursued by leopard seals, andcommonly the penguins get out of the water as fast

• . suddenly the seal reversed itself,reentered the water, swam under the floe,and appeared again . . . in Orde-Lees'

path."

as possible. Apparently penguins and perhapssmaller seals can outmaneuver leopard seals inopen water. But near shore, where maneuverabilityis restricted and there is some element of surprise,leopard seals can more easily capture their prey.

Leopard seals and humans

Leopard seals occasionally have confrontedhumans. As far as we know, however, there havebeen no injuries. These seals have been known tolunge or chase after people standing on beachesor ice. According to A. Lansing's (1959) accountof Shakleton's ordeal when Endurance was besetin the Weddell Sea, a leopard seal leaped frombetween ice floes and began to chase the store-keeper, T. H. Orde-Lees. Orde-Lees fled acrossthe floe with the seal in pursuit when suddenlythe seal reversed itself, reentered the water, swamunder the floe, and appeared again from betweenfloes in Orde-Lees' path. The animal then lungedfor the man with its mouth open. The episodeended when the second in command, F. Wild, ap-

proached the scene with a gun, and the seal bega r.to move toward him. Wild killed the seal witFseveral shots.

Zimmerman (1965) also reported several encounters with leopard seals during his stay on thMelchior Islands (immediately north of Anver4Island). In one of these encounters a colleague waexamining intertidal organisms on a rocky area thawas flanked by high ice and snow banks. A leopardseal appeared, cutting off his colleague's retreaand forcing him to keep the animal at bay by throwing chunks of ice. The animal was eventually dis-couraged and escape was accomplished.

W. Curtsinger, while diving along the AntarcticiPeninsula in 1970, was approached closely under-water by a leopard seal. Curtsinger managed tophotograph the seal at very close range (Matthewsand Curtsinger, 1971) before he left the water.Bellisio and Tomo (1974, page 159) reported thatArgentine divers also have seen leopard sealsunderwater, and that their divers have always left 4the water without incident.

Although some of these accounts may be partia11fanciful or incomplete, it is this kind of informa -tion—as well as the leopard seal's physical appear-ance—on which the animal's threat to humans isbased.

Documented confrontations, 1971-1975

Members of our research group, working on theAntarctic Peninsula where leopard seals are corn,mon, have observed or participated in many sur-face and underwater encounters with these seals.Since December 1971 we have documented theseevents to assess the dangers posed by leopardseals. Our findings are summarized below.

(1) On numerous occasions we and others inmotorized rubber boats have approached leopardseals on ice floes or bergs. In most of these cases,after eying the boats and their occupants, theanimals have slipped into the water and disap-peared. Other animals simply have reared andopened their mouths while remaining on the ice.R. Hofman and assistants have approached, anes-thetized, and tagged many leopard seals resting orsleeping on floating ice in the Arthur Harbovicinity without serious incident. Leopard sealseem unaggressive when surprised on ice.

(2) In January 1972 P. Jacobs and A. Owenwere crossing Arthur Harbor, adjacent to PalmeStation, in a small, motorized whaleboat, when ^penguin with blood oozing from several puncturewounds in its breast leaped from the water intothe boat. A leopard seal immediately surfaced and

86 ANTARCTIC JOURNAL

ram in circles around the boat, coming next toe boat and lifting its head high to see inside.essrs. Jacobs and Owens drove the boat away asst as possible because they believed their livesuld be in danger if the seal decided to enter or

tack the boat. The seal in this case seemed moreterested in completing its capture of the penguin.

• . a penguin with blood oozing fromeveral puncture wounds in its breast

leaped . . . into the boat."

(3) The only encounter involving physical con-act occurred underwater in January 1972. Mr.eLaca was bumped hard by a large seal while heas diving at 10 meters under some kelp in Arthurarbor. The animal struck a glancing blow tor. DeLaca's scuba tanks, spinning him around.he dive, however, continued for several moremutes without further incident. Upon surfacing,leopard seal was seen circling the dive boat, and

he tender reported that the animal had been inhe area for 10 minutes or so. Mr. DeLaca con-luded he had been hit by that animal, althoughe did not actually see the seal strike him.(4) InJanuary 1973 Mr. DeLaca and A. Gianinni

were ascending from a 30-meter dive at Sail Rock,ear Deception Island, when they saw a leopard

seal capture a penguin just above them. The pen-guin was grabbed quickly by the seal and taken outf view, leaving only blood and feathers in the

water. The divers terminated their dive, boardedhe boat, and motored away without incident.

Again the seal appeared to be interested only inthe penguin.

(5) Later that same month, Messrs. DeLaca andGiannini were diving in the channel next to PalmerStation. W. Stockton, the boat tender, saw a leopardseal approaching and notified the divers by under-water communication gear to terminate their dive.Seconds afterwards, the divers observed a large sealflash by in the murky water; the divers entered theboat rapidly. The seal remained nearby for thebrief time it took to start the boat. As the boatmoved away the seal followed for over 100 meters(all the way to the Palmer Station dock), rearingits head out of the water and lunging to within ameter of the boat's transome. At the dock the men

scrambled up a ladder while the seal swam vigor-ously back and forth near the dock, rearing out ofthe water in what was interpreted at the time as anaggressive display.

(6) In October 1973 Mr. Gianinni and P. Haleywere swimming along a transect line at 12 metersafter collecting samples near Palmer Station. Aleopard seal appeared. It swam in circles aroundMr. Gianinni for several minutes. Mr. Gianinniused his bulky camera housing for protection asthe animal approached, and he worked his way tothe Palmer Station dock. The leopard seal seemedto lose interest as the divers left the water. Thedivers' interpretation was that the animal was onlycurious.

(7) In January 1974 R. Moe and N. Temnikowtraveled to Sail Rock in a 3.5-meter, motorizedinflatable boat. Before they entered the water fora planned scuba dive, a large leopard seal rapidlyapproached the boat, circling and lying in the waternear it. Abandoning their diving plans, the men leftin the boat. The seal followed them closely for over100 meters, occasionally lifting its head clear of thewater. This animal also seemed to be attracted onlyto the boat and motor.

(8) On several occasions divers have been ap-proached by leopard seals underwater when theywere unaware of it. For example, in January 1974Messrs. Gianinni, Lipps, and Temnikow were div-ing in shallow, low-visibility water adjacent toPalmer Station when a leopard seal approachedand swam near the divers but was not seen bythem. People gathered on shore and reported thatthe seal swam among the divers. No contact wasmade, with the seal who again seemed merelycurious.

(9) During that same season, Messrs. Moe and

the seal had followed them and waslying in the water under the boat."

Temnikow were preparing to dive adjacent to theJoubin Islands, near Arthur Harbor, when theynoticed a leopard seal close to the boat. They de-cided to avoid the animal and moved the boatapproximately 400 meters to an alternate divesite. As they prepared to enter the water theydiscovered that the leopard seal had followed them

May/June 1975' 87

rPhotos by T. E. DeLaca

Figure 1. The leopard seal commonly positioned itselfbetween the retreating divers and their only place of escape—

the shore.

and was lying in the water under the boat. Althoughthe seal did not again follow the boat when it leftthis last station, it apparently was curious about itwhen it first arrived.

(10) A more serious encounter occurred onFebruary 2, 1974, between Messrs. DeLaca andZumwalt and three leopard seals. The divers weredescending a submarine cliff off Janus Island inArthur Harbor when, at a depth of 22 meters, alarge leopard seal (approximately 4 meters inlength) approached from shallower water to within4 meters of the men. The seal only appeared tobe curious so the dive was continued. At 32 meters,after they began to collect specimens, two morelarge leopard seals appeared and the original seal

Figure 2. The leopard seal made further progress Impossibleby Its constant presence.

88

became more aggressive. It became obvious tlithe situation had become serious and that the dishould be terminated. Leaving their collecting aparatus and only carrying camera gear they movup the cliff with the original seal still followinga distance of 7 to 10 meters. The other two sedisappeared.

At a break in the vertical cliff face at 21 metein depth the behavior of the leopard seal changmarkedly.: it began to approach more closely. Unabout 10 meters in depth the divers were forcedslow their ascent because of the repeated and doapproaches of the seal. The seal appeared moagitated as the divers approached shore, spenditmore time at increasingly closer inspections. 4

approximately 7 meters the divers found metelong pieces of angle iron, which they held betwethemselves and the seal as they continued theascent. At 5 meters they were trapped in a roalcove for 30 minutes (figure 1). Further progretoward shore was prevented by the now consta:presence of the seal. The seal breathed at the suface immediately above the divers (figure 2) ar

"The seal . . . shook its head vigorouslfrom side to side and blew bubbles mt

the water."

then returned to within a meter of them, hoverinin the water with its nose about 0.3 meter from thend of the angle iron and repeatedly striking athe end of the angle iron. When striking, the seawould bend its neck into an "S" or coil it (figure3 and 4). It seemed more aggressive for it increasedits swimming rate and frequency of striking as timepassed. The seal never opened its mouth, althoughit shook its head vigorously from side to side andblew bubbles into the water. When the animal re-turned to the surface for prolonged breathingperiods, it frequently positioned itself between thedivers and the only shoreward escape route pos-sible.It also positioned itself in the sun. The diverwere thus forced to look into the sun to keep theseal in sight. The seal's movements were difficult tofollow because after leaving the bright surface itapproached from unexpected directions of sub-dued lighting (figure 5).

This sequence of events averaged 15 to 20

ANTARCTIC JOURNAL

1gures 3 and 4. While hovering, the leopard seal would "S" curve its neck prior to striking. When It struck, Its muzzlemoved approximately 0.3 meter with surprising quickness and force.

seconds. Finally a break in the sequence occurredwhen the boat tender succeeded in distracting theseal, thereby allowing Messrs. DeLaca and Zumwaltto swim up a tide channel and leave the water. ThisWhole confrontation lasted for approximately 45Ifflnutes.

(11) Messrs. DeLaca and Zumwalt encounteredinother smaller leopard seal (2.5 meters in length)figure 6) underwater on February 5, 1974, in thehannel next to Palmer Station. Because of their

previous experience they carried a meter-long staffWith them. At 13 meters the seal approached andpositioned itself between the divers and the shore.'The divers were forced to wait as the seal con-inued to swim closer. Unlike their first encounter,

\vhere the divers only used the angle iron defensive-

Figure 5. The animal's extreme speed and maneuverability,and abrupt changes in light intensity from the bright surfaceto the murky depths, made It difficult for the divers to follow

the seal's movements.

ly, Mr. DeLaca several times swam at the seal for1 to 2 meters with the staff extended. This youngeranimal performed the same striking behavior as theprevious seal, but when charged it back away andthere was no contact. After 20 minutes the diversreached a depth of 7 meters and a place that of-fered a favorable exit. While the seal was momen-tarily distracted they escaped to shore. The sealswam around in the immediate area for severalminutes and then remained in the general area forsome time thereafter.

(12) On January 21, 1975, Mr. DeLaca and W.Showers were scuba diving near Palmer Stationwhen, at 23 meters, a small leopard seal appeared.The divers stopped sampling and moved along thebottom toward shallower water and shore withintermittent interruption by the seal. Their prog-ress was reduced as they neared shore by the

Figure 6. The younger and smaller seal that approached thedivers on February 5, 1974.

May/June 1975 89

constant presence of the leopard seal, which bythis time had approached to within a meter. Theanimal seemed to be playful and only curious; thedivers moved past it to shore. The leopard seal lostinterest and left as the divers climbed out of thewater.

(13) On January 25, 1975, D. Parmelee and twoassistants in a zodiac boat were attacked by a verylarge leopard seal as they approached BreakerIsland, Wylie Bay. The seal swam with rapid move-ments under their boat and with its mouth openstruck the bottom of the boat. On several occasionsduring this confrontation the seal surfaced and bitat the pontoons that formed the sides of their in-flatable motor boat. This encounter lasted morethan 10 minutes. The seal eventually lost interestand moved on.

Dr. Parmelee reported that apparently the sameleopard seal had approached his party on previousexcursions to Breaker Island and that it had be-come progressively more aggressive with each suc-cessive encounter. Until this incident, however, ithad never made physical contact with the zodiac.

(14) A potentially dangerous situation developedin February 1975 when D. Lame entered the waterfrom a moored zodiac in the channel adjacent toPalmer Station. After Messrs. Lame and Temnikowcompleted predive preparations, Mr. Lame en-tered the murky water. He began swimming justbelow the water's surface toward what appearedto be the moving silhouette of his diving partner.As he drew nearer he realized that the silhouettewas that of a leopard seal that was swimming,open-mouthed, toward the zodiac. At that momentMr. Lame's presence distracted the seal, whichthen turned to confront him. Mr. Lame quicklyreentered the zodiac. Mr. Temnikow, who wassitting on a submerged rock platform alongsidethe zodiac, felt the leopard seal as it brushed byhim. The seal left and did not return.

ConclusionsPrecautions with leopard seals

(2) While active in the water, leopard seals arcattracted to unusual noises or vibrations; foexample, small boat motors and propellers andthe sounds that scuba divers make. M. G. White,British Antarctic Survey, also concluded this fronihis experience at Signy Island, northeast of thAntarctic Peninsula (personal communication,1974). We think these animals are just curious.

(3) When hunting, leopard seals can be dan-gerous if people somehow interfere in the chase.Once their prey is taken, however, the dangesubsides.

(4) After a period of time, leopard seals confronting submerged scuba divers may become aggressive. This behavior may be interpreted as anattempt to flush prey, "playfulness," increasingcuriosity, or some sort of prey-capture procedure.We exclude the prey-capture possibility becausethe seals never made an attempt to seize divers,even unsuspecting ones. Of the remaining possi:bilities, we interpret their behavior—especially thtstriking action—as an attempt to flush divers intoflight. Had this occurred, the seals might possiblyhave attempted a capture (they ordinarily capturelarge animals swimming in open water). Our diver!'have always been close to rocky cliffs during en-counters with leopard seals; these solid surfaceshave been used for protection.

Since humans are not the normal prey of leopar4seals, scarcity of food may enhance seal inquisitive.ness. Field notes taken in the Arthur Harbor areduring late January and early February 1974 indicate a decrease in local krill and an increase ileopard seals. Further, during this period leoparseals displayed a behavior similar to that describeby Penney and Lowry (1966) for leopard seapredation on penguin chicks 1 to 2 weeks beforemost of the chicks actually entered the water. Wthink that these conditions may have indicatedfood shortage and may have contributed to ouencounters of February 2 and 5, 1974.

Leopard seals are sophisticated top-level carni-vores. They, like many high-latitude organisms, areextremely generalized and opportunistic in theirfeeding habits. Their behavior undoubtedly isquite complicated. Based on our field observationswe nevertheless have drawn the following generali-zations concerning their interactions with humans:

(1) Leopard seals on ice floes are not especiallydangerous when surprised by boats or people.They usually flee or remain stationary. In mostcases they merely seem to want to escape (unlessthey feel cornered). They may charge, but thenprobably only to an avenue of escape.

Leopard seals obviously pose a potential danger -to humans, if for no other reason than their largesize and close approaches. We have formulatedprocedures to reduce these hazards when peoplemust work in or near the water. Although theyseem logical, based on our observations, theseprocedures have not been tested many times. Wepresent them because we have seen people previously inexperienced with leopard seals panic anddo inappropriate acts. Hopefully our procedureswill encourage discussion and awareness in othergroups working around leopard seals.

(1) The work site vicinity should be inspected

90 ANTARCTIC JOURNAL

for leopard seals prior to beginning work. No workshould be attempted when active leopard seals areseen within about 400 meters. Personnel shouldnot remain in the area when active leopard sealsare present.

(2) An assistant should maintain a watch forleopard seal activity while the work is in progress.If seals are sighted, the assistant should signal theworkers to abort their activities and should alsoalert the base station or ship by radio, if possible,that assistance may be necessary.

Diving in Antarctica presents special problemswith regard to leopard seals. We have used thefollowing procedures:

(1) While in the water, one diver is specifi(allybarged with keeping watch for seals.(2) Divers carry sturdy poles or rods of at least

1.5 Dieters in length to ward off seals.(3) If an underwater encounter with a leopardal occurs, a diver should observe the following

procedures:(a) Notify the partner that a seal has been

ighted. Both divers should stay together with rodsinted at the seal and their backs against the rocks.

f they are on a flat bottom, the divers should dropo the bottom. In open water, the divers shouldack together. As soon as possible, the divershould make their way slowly to the surface, keepingext to cliffs if possible. They should not rush tohe surface or make a quick break in open water.

(b) Should one diver have trouble (runs out ofair, drops a fin, mask, etc.) the other diver shoulddistract the seal and protect his or her partner.

(c) Upon approaching the surface, the diversshould exit the water on land and not into a boat.Both divers may be able to exit onto shore easily,whereas the diver exiting into the boat may jeo-pardize the diver remaining in the water and/orthe boat tender.

(d The boat tender should try to distract theSeal(s) by waving arms and slapping the water orthe 3eal with an oar. The tender should not startthe fliotor until the divers are ashore.

(e)i If the station's or ship's crew has come toassist, the boat tender should direct them to goasho'e to assist the divers' exit from the water bydistricting the seal and helping in any other waypossb1e.

(f) When the divers are ashore, the boat tender,hoi4d start the motor and move away from thecen while at the same time trying to get the sealto fo1ow as the divers climb higher on shore. Thedivers should be picked up later or at a differentand safe spot along the shore, unless circumstanceswarr tnt otherwise.

W have considered other methods of protecting

May4june 1975

ourselves from leopard seals; for exarnpk somesort of electric prod, "shark darts" that dischargecarbon dioxide through a hypodermic-style tip,shark "bang sticks" that fire a cartridge uponcontact, shooting the seals as they surface, or using"seal bombs" (firecracker-sized explosives) at thesite prior to making dives. At present, these alter-

"Avoidance is of course the best solution."

natives seem ineffective and even more hazardousto the divers than to the seals. We prefer a morepassive, slow retreat to other methods that mayantagonize the seals. Avoidance is of course thebest solution.

We thank all the members of our diving teamwho, despite some terrifying experiences, re-mained composed and clearly reported their en-counters: T. Brand, R. Daniels,. M. Erskian,T.Kauffman, W. Krebs, and Messrs. Giannini, Haley,Lame, Moe, Showers, Stockton, and Temnikow.Drs. Parmelee, Hofman, and Owens discussed theirexperiences with us. Our project to study thebiology and ecology of benthic foraminifera is sup-ported by National Science Foundation grants GV-31162 and 74-12139.

References

Bellisio, Norbetto, and A. P. Tomo. 1974. BiogeografIa dela Peninsula Antartica, archipielagos y mares adjacentes.Buenos Aires, Servicio de 1-lidrografia Naval, InstitutoAntartico Argentino, Dirección Nacional del Antartico.Publication, H-918. 222p.

Hamilton, J . E. 1934. The southern sea lion, Otaria hyronia (deBlainville). Discovery Reports, 8: 271-318.

Hofman, R. In press. Leopard seal movement and behavior atPalmer Station, Antarctica. Washington, D.C., Third SCAR/IUBS Symposium on Antarctic Biology (August 1974). Pro-ceedings.

Lansing, A. 1959. Endurance (Shackleton's Incredible Voyage).McGraw-Hill. 282p.

Matthews, S. W., and W. R. Curtsinger. 1971. Antarctica'snearer side. National Geographic, 140(5): 622-655.

Müller-Schwarze, D. 1971. Behavior of antarctic penguins andseals. In: Research in the Antarctic (L. 0. Quam, editor). 259-276.

Penney, R. L., and G. Lowry. 1967. Leopard seal predation onAdélie penguins. Ecology, 48(5): 878-882.

Peterson, R. S. 1965. Animal ecology in Antarctica. PacificDiscovery, 18: 2-9.

Ray, C. 1966. Snooping on seals for science in Antarctica.Animal Kingdom, 69(3): 66-75.

Scheffer, V. B. 1958. Seals, Sea Lions and Walruses. StanfordUniversity Press.

Zimmerman, M. H. 1965. Among leopard seals and killerwhales: we dived in the Antarctic. Neptune, 5(12): 348-352.

91