Observations on the Diving Behavior of the Northern Fulmar

NOTES

OBSERVATIONS ON THE DIVING BEHAVIOR OF THE NORTHERN FULMAR

TERENCE R. WAHL, Departmentof Biology,Western Washington University, Bell- ingham, Washington98225

Northern Fulmarsare relativelylight weight, aerial seabirds,and are not anatom- ically well-adaptedfor diving or underwaterswimming. However, Fisher(1952) stated,"the literatureis full of controversyabout the divingof fulmars."He listedeight observersreporting diving; presumably their reportsrepresented most of the detailed descriptionsof this behaviordiscovered during an extensiveliterature search con- ductedon the species(see Fisher 1952). Subsequentpublished reports are few if any. Descriptionsin more recentreferences (e.g. Palmer 1962, Cramp 1977) apparently are derived from Fisher'ssynthesis. Ashmole (1971) listed the fulmar's feeding methods as surfaceseizing, surface filtering, scavengingand pursuit diving (which is classifiedas "of minor importance").Cramp (1977) statedpursuit-plunging is "infre- quently"employed. There is disagreementon the depthto whichfulmars dive, with estimatesof depthsranging from 18• to 2 fathoms(0.5 to 4 m) or more. On 4 July 1983 I was aboardthe T.V. OshoroMaru which was leavinga salmon gill-netsampling station at 55ø00'N 147ø30'W in the northernGulf of Alaska.About 25 Northern Fulmars (Fulmarusglacialis), 4 Black-looted Albatrosses(Diomedea nigripes), 6 Fork-tailed Storm-Petrels (Oceanodromafurcata) and 1 Short-tailed Shearwater (Puffinustenuirostris) were gathered at the offal slickwhich was apparent even on the relativelycalm sea surface.This group wastypical of the relativelysmall assemblagesnoted during my 2-weekcruise. As the shipgot underway, a dark-phase fulmar flew in and landed within 1 m of anotherdark-phase fulmar alreadypresent. The newcomerlunged aggressively with opened beak and half-openedwings to drive the other bird back 1-2 m, and then abruptlyreared-up on the surfaceand dove almostvertically with wingspartially opened. It poppedto the surface6 secondslater, swallowedsomething, waited perhaps4 seconds,and dove again for 6 seconds.I then lost track of the bird as the ship moved off station. After I recoveredfrom the surpriseof actuallyseeing a fulmardive, questionscame to mind. How frequentlydo fulmarsdive? Under what conditions are fulmarslikely to dive? I contacted other observerswho have watched numbers of fulmars feeding at sea and found two who recall seeingfulmars dive. R.G.B. Brown (pers. comm.) reportedseeing fulmars dive on three occasionsin the GreenlandSea and Baffin Bay. Singlebirds on two occasionsand two birdson another submergedfor 3 to 5 seconds whilefeeding apparently on planktonicitems. In all casesbirds dove from the surface. A bird submergedfor 3 secondswas feeding where Black-leggedKittiwakes (Rissa tridactyla)were plunging and submergingto tails and wingtips--a depth of about 40-50 cm. In the North Pacific,H. Ogi (pets.comm.) experimentedwith baits suspended from a floatingwooden bar at sevendepths, ranging from 20-200 cm. Many fulmarswere unwillingto approachthe floatingbar and birds were frightenedaway after one becamehooked on the line. Some fulmarsdove for bait duringthree "sets,"but they did not try for bait at a depth greaterthan 80 cm. Fisher (1952) thoughtthat fulmarswill dive, "with enough stimulus,e.g. for light- colouredfatty stuff." I have seen frenziedfulmars rush to choice,just-jettisoned fish entrailsonly to watchthe food sink,just out of reach,with no more effortemployed by Western Birds 15:131-133, 1984 131 NOTES

the birds than submerginghead and neck before giving up. The bird I saw dive for 6 secondswas probablywell belowthe surfaceand couldhave retrievedlarge amounts of food other fulmars missed.Is food normallyso plentifulthat individualfulmars becomesufficiently motivated to diveonly when desperatelyhungry? The aggressive feeding behavior displayed by fulmars on many occasionsmay make it hard to distinguishextremely hungry birds. And of coursecertain choice food items might "turn-on"any fulmarto diving.This possibility should be investigated."Natural" foods taken by fulmars (see Fisher 1952) apparentlycome from the surfacelayer. The relativeimportance of nocturnalfeeding by fulmarsand other seabirds,particularly pelagicspecies, is almostunknown. Possibly fisheries discards are lessimportant in the fulmar'sdiet under many circumstances than is often believed. Perhaps enough of this offalis availableat the surfaceso thatwhat sinksis usuallyunimportant and not worth the effort of underwater retrieval. Do fulmarsdive only when more agileunderwater retrievers (e.g. shearwaters)are not present?Fulmars feeding at vesselsin areaswhere aggressivesurface-feeders like gullsand underwaterfeeders like shearwatersare presentcan be seento be at an ob- viouscompetitive disadvantage because they neitherfeed by "dipping"from flightnor fly as adeptlyin closequarters as gulls,nor do they (normally)catch or retrieveitems underwaterlike shearwaters.Fulmars often appear to compensatefor this disadvantage by crowdingcloser than other speciesand aggressivelycontending for whatever comeswithin reach. Even where there was no subsurfaceavian competitionfor sink- ing food, however, I have seen thousandsof fulmarsfeeding at pelagic sourcesof discardsand have witnessedjust thisone incidentof diving. And when this incident took place there was much lesscompetition for discardsthan on many other occa- sions.Several times I haveobserved adult Glaucous-winged Gulls (Larus glaucescens) divingfrom about 1 m abovethe surfaceand (barely)submerge while attemptingto retrievesinking food. However, I observedthis behavior only when very few other birdswere competingfor the food. To gullsand fulmars,diving is likelyonly margin- allyworthwhile energetically. Are thesebirds more inclinedto divewhen competition is minimal or lacking? Have fulmarslearned to dive only recently,with the adventof "industrialfishing?" While this presumablycould have been the case in the Atlantic (see Fisher 1952), observationsby Anthony (1895) and Linton (1908) would seem to predateintense, largescale effort in the Pacific.It is clearthat thisaggressive, successful species, with its long-documentedassociation with man, has long includedat leastsome individuals that couldand did dive. Fulmarshave been known to divefor manygenerations, and divingis not restrictedto one populationor another. Have only certainindividuals adopted the divingtechnique? Due to the apparentin- frequencyof encounterswith divingfulmars, this question is likelyunanswerable. The value of divingbehavior may be marginalenough for fulmarsso as not to reflectin its spreadthroughout a population. The reportsgiven here indicatefulmars may diveat naturalfeeds and alsofor fishing discards,and to relativelyshallow depths. Further experiments would be of great in- terest. Descriptionsof prey taken during diving are needed to documentthe type of "pursuitdiving" employed. Do fulmarsactually "pursue" or do they simplyextend their reach toward relatively inactive plankton?In the case of discards,perhaps "retrievaldiving" is what fulmarsactually perform. Perhaps,though it seemsunlikely, other observers are seeinglots of fulmarsdiving. Responseto this note may documentand explainthe extent of this "controversial" behaviorin a speciesotherwise well-known. Thanks are due the Facultyof Fisheries,Hokkaido University,Dr. H. Ogi, and Capt. T. Fujii of the T.V. OshoroMaru for my attendanceon severalresearch cruises in the North Pacific.J.R. Jehl, Jr., and S.M. Speichvery helpfullyreviewed an early versionof this note. R.G.B. Brown and H. Ogi also kindlyfurnished field notations.

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LITERATURE CITED Anthony,A.W. 1895. The fulmars of southernCalifornia. Auk 12:100. Ashmole,N.P. 1971. Seabird ecology and the marine environment. Pp.223-286 in D.S.Farner, J.R. King & K.C.Parkes, eds., Arian biology, Vol. 1. Academic Press, New York. Cramp,S., ed. 1977. Handbook ofthe birds of Europe, the Middle East and North Africa.The birds of the western Palearctic, Vol. 1. OxfordUniv. Press, New York. Fisher,J. 1952.The fulmar. Collins, London. Linton,C.B. 1908. Pacific fulmars and Pacific kittiwakes at Long Beach. Condor 10:238. Palmer,R.S., ed. 1962. Handbook ofNorth American birds, Vol. 1. YaleUniv. Press,New Haven, CT.

Accepted26 April 1984

Northern Fulmar Sketchby Tim Manolis

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