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Biological Sciences Publications Department of Biological Sciences

2002

An Australian Pelecanus conspicillatus benefits from the beating behaviour of a Pied Phalacrocorax varius: a possible precursor to

O. P. Love University of Windsor

Christina A.D. Semeniuk University of Windsor

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Recommended Citation Love, O. P. and Semeniuk, Christina A.D., "An Pelecanus conspicillatus benefits from the beating behaviour of a Pied Cormorant Phalacrocorax varius: a possible precursor to kleptoparasitism" (2002). Corella, 26, 1, 27-30. https://scholar.uwindsor.ca/biologypub/1035

This Article is brought to you for free and open access by the Department of Biological Sciences at Scholarship at UWindsor. It has been accepted for inclusion in Biological Sciences Publications by an authorized administrator of Scholarship at UWindsor. For more information, please contact [email protected]. Corella, 2OO2,26(1'1:27-30 AN AUSTRALIANPELICAN Pelecanus conspicitlatus BENEFITSFROM THE BEATINGBEHAVIOUR OF A PIEDCORMORANT Phalacrocorax vATiusiA POSSIBLEPRECURSOR TO KLEPTOPARASITISM

O. P.LOVE andC. A. D. SEMENIUK

Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Bumaby, British Columbia, V5A 156 Canada

Received:27 December2000

Food on pelican by many groups of , especially Larus and Sterna spp. is well known and documented.Although the Pelicanidaeexhibit many behaviouraland ecologicaltraits known to facilitate parasitism,few accountsand studiesof this feedingstrategy by pelicansare known.The followingreport describes a series of inshore parasitic bouts by an Australian Pelican Pelecanus conspicillatuson a Pied Cormorant Phalacrocorax varius in Monkey Mia, Bay, Western .The pelican made no attempt to feed prior to the arrival of the cormorantand remained in associationwith the cormorantlor well over a quarter of an hour.The observedbehaviour was clearlyone ol interceptionof prey by the pelicanand not merely of capitalizing on irod which could not escape. Ecologicaland behaviouralfactors known to encourage parasiticbehaviour, 'beating', such as are discussedin relationto these observations,as is the possibilityof this feedingassociation leading to kleptoparasitism,or food theft. Potentialcosts and benefitsof this associationfor both species are briefly discussed,as is the possibilitythat the associationwas precipitatedby the protectionafforded by the physicalpresence of humans and their structures.

INTRODUCTION METHODS Many birds are known to take advantageof the feeding Study site activities of other which frighten prey, a 'beating' Shark Bay (Fig. l) is a large (13 000 km2),shallow basin behaviourknown as (Rand 1954).Such feeding containing the largest seagrass meadows in the world associationsmay lead to kleptoparasitism,or food theft, (Walker 1989). In addition, the basin is home to many which is a fairly common foraging strategy occurring in species protected through a World Heritage Site listing, many species (see Brockman and Barnard 1979 for including breeding colonies of the Australian Pelican and review). In addition, parasitic behaviour can arise under Pied Cormorant (Burbidge and Fuller 2000). However, a number of different ecological and behavioural although listed as a World Heritage Site, there exists a conditions (Brockman and Barnard 1979).Although the substantialhuman presence,especially at the resort parasitic and kleptoparasitic associationsbetween Brown in Monkey Mia (Fig. l), located on the Eastern side of Pelecanusoccidentalis and their laras spp. Peron Peninsula(72"00'5, 115'00'W). This is one of the and tern Sterna parasites spp. has been well studied few locations in Australia where the public may witness (Schnell et al. 1983; Carrol and Cramer 1985; Tershey human-subsidizedfeeding and close-upencounters of wild et al. 1990; Shealeret al. 1997),kleptoparasitic behaviour Bottlenose Tursiops aduncus. This activity, in in the Pelicanidae has been documented in only one addition to that of recreational fishers and boaters species, the Pelecanus combined with small-scalecommercial fishing in the area, erythrorhyncftos (Johnson et al. L996). This specieshas draws many birds to the potential sources of food and been observed parasitizing and kleptoparasitizing shelter afforded by humans. In addition to the numerous conspecifics as well as Ospreys Psndion haliaetus, Silver Larus novaellandidiae present round, a Double-crested Phalacrocorax auritus arrd group of 6-10 Australian Pelicans are usually in close Great-blue Ardea herodlas (O'Malley and Evans associationwith the resort. These birds obtain some of their 1983; Hart 1989; Anderson l99l; Johnsonet al. 1996). subsistencefrom distraction feeding by rangers targeting We discuss the parasitic behaviour exhibited by an select dolphins for tourist interaction, as well as from Australian Pelican Pelecanusconspicillatu.r on a foraging handoutsby recreational fishermen returning from trips and Pied Cormorant Phalacrocorax varius. We also dicuss the preparing their catches on shore. The pelicans' nearly ecological and behavioural factors which can lead to this continuous presence along the shoreline around human type of association and briefly introduce how this may structures at the resort predisposes them to be able take lead to kleptoparasitism. advantageof other speciesforaging in the same area. 2A O P Love and C. A. D Semeriuk AustralianPelican bonefits from behaviourol Pied Cormorant Corelta26(1)

I130 I 140

FiEwe \. b.ation,nap, showing the position of Shark Bat on the W?st At'ltrclian rcastline and tlrc obsenation site (*) Monkey Mia. March, 2002 O. P Love and C. A. D. Semeniuk: Australian Pelican benelits from behaviour of Pied Cormorant

Real-time field notes from surface observations were observed this associationin Snowy Egretta thula used as the basis for the following description which was relying on flocks of Red-breasted Mergansers Mergus recordedduring another study in Shark Bay. serrator to locate and obtain fish, where the egrets made no attempt to feed prior to the mergansers' arrival. Only OBSERVATIONS when the mergansersapproached the shoreline, driving schools of fish in front of them, did the egrets begin At approximately 1400hrs, on the 25th of June 2000, feeding. a single Australian Pelican was observed 10 metres from the shoreline approachinga foraging Pied Cormorant off As noted by Brockman and Barnard (1979) a number of Monkey Mia Dolphin Resort. The tidal sequenceat the ecological and behavioural factors in this pelican-connorant time of observationwas high-rising with a high-tideof 2.41 associationcould facilitate parasitic behaviour.Firstly, the metres occurring at 1450 hrs. Soon after the observer's presenceof large quantities of food, such as schools of fish arrival, the pelican was observed following the Pied herded by the cormorant near the shoreline, cannot be Cormorant which was engaged in underwater foraging monopolized or protected by an individual foraging behaviour in 50 centimetres of water, parallel to the shore. cormorant and hence the pelican is able to take advantage. The pelican swam parallel to the cormorant in a water Secondly, the habits of the in this case are very depth of 35 centimetres keeping 1-2 metres to the shore- predictable. The cormorant forages in more or less a side of it and angled slightly behind it. When the foraging straight line with side to side movement limited by the cormorant located and chased a small school of fish shoreline and the pelican. Thirdly, the diving and towards the shoreline,the pelican quickly acceleratedand resurfacing behaviours of foraging cormorants are highly swam in front of the cormorant, intercepting at least part visible, reducing the chances of the pelican chasing a of the catch. At this point, the cormorant surfacedfor air cormorant host which has not located food. This in turn and resumed its underwater foraging as the pelican reduces the amount of time and energy invested by the followed. The cormorant would forage in this manner over pelican. Finally, it has been noted by severalauthors that a distance of approximately 35 metres at which time it kleptoparasitism by many species increasesduring periods would surfaceand turn 180'to begin anotherfeeding bout of food shortage, tides or during the winter months in the oppositedirection. As it did, the pelican also turned (Palmer 1941; Munro 1949; Snow 1958; Bergman 1960; to stay betweenthe foraging cormorant and the shoreline. King 1966; Hays 1970). These observationstook place During this period, the pelican was seento interceptthe during Australia's winter and further study is needed to cormorant's potential catches 17 separatetimes and was determine the influence of this factor together with food observedswallowing prey during some of theseoccasions. shortageon the observedbehaviour. The cormorant was observed swallowing prey on 10 Although kleptoparasitism in the strict senserefers to the occasionsduring the association,although it was difficult stealing by one of food which has already been to note whether thesewere single or multiple-fish catches. caught by another (Brockman and Barnard 1979; Vickery All prey chased and captured by the cormorant appeared and Brooke 1994), the associationdocumented above is to be small (7-10 cm) bait fish, however,the small size of more than casual opportunism and can be viewed as a the prey items coupled with speed of the feeding bouts precursor to the development of kleptoparasitism. made it difficult to determine the exact number of prey Kleptoparasiticbehaviour can developas one speciesrelies both birds captured.The cormorant made a total of four solely on food chasedup or frightened by another,ceasing foraging bouts in a north to south direction and three bouts to forage independentlywhile in that association.As stated in the returning south to north direction. On several by Brockman and Barnard (1979), one of the conditions occasions,the cormorant swam quickly at the surface of facilitating the evolution of kleptoparasiticbehaviour is the the water with its head and partial body out of the water, fixed location or predictability of the host's foraging ending in a dive, perhaps in an apparentattempt to rid itself habitat. Since Pied Cormorants have been seen to forage of the pelican, while remaining in the immediate foraging within a narrow band along the shoreline around Monkey area.The pelican would speedup its swimming to remain Mia (Love, unpubl. data), especially in associationwith in close association with the foraging cormorant. The human settlements, they follow a predictable feeding observationperiod lasted for l8 minutes. The association patternwhich createsideal conditions for kleptoparasitism. ended when the cormorant surfaced and flew to a distance The birds can further take advantage of human-made greater than 350 metres out into the bay. The pelican structures such as moorings and moored boats to conal continued on its original path along the shoreline in a south their prey. In addition, the proximity of the shorelineand to north direction to join a group of pelicansroosting and the presence on the shore. of humans and their structuresreduces most potential predators and competitors for large, aquatic foragers DISCUSSION which can tolerate close human presence.Both pelicans and cormorants in the bay have been observedto Birds can specializewithin a range of socially parasitic utilize the shoreline close to human features to corral prey behaviour (Brockman and Barnard 1979). One exampleof (Love, unpubl. data) and this may be an important present such specialization is when birds take advantageof the sourceof prey for thesespecies. The close matchingof the feeding activities of others which frighten prey, a behaviour pelican 'beating' to the cormorant's movements coupled with the known as (Rand 1954). The pelican stole food cormorant ending the associationwould seem to indicate chased and herded by the cormorant without the pelican that the pelican was indeed benefiting during the attempting to feed on its own. Emlem and Ambrose 0970) association.There were no predatory or human disturbances O. P.Love and C.A. D SemenlukAustralian Peucan benefits from behaviour of pied Cormorant Co.ella26(1) noted at the point at which the cormorant left the Bergman,G. (1960).Ube treueFuttergewohnheiteo der Mdwen an den association.Fu hermore, as the pelican joined the already KiisteoFinnlands. Ornis FennicaX7'. ll-28. Brockman,H. J. and Bamard,C. (1979).Kleptoparasitism foraging cormorant, it is possible J. in birds. that the association Anim. Behar.27t 487 514. favours the pelican to an extent where it seeksout a shore- Burbidge,A. A. and Fuller,P J. (2000).The breediDgseabirds of Shark foraging cormorant. The pelican exerts no energy in Bay,Westem Australia. CALM Science3(2)t 109-124. searching for prey and can easily assesscormorants in Carrol, S. P. and Cramer, K. L. (1985). Age differences in gulls, good feeding areas due to their conspicuousforaging kleptoparasitismby laughing lzrxr dtricilld, on adult and juvetrile brown pelicans,Pelecanur occidentalis. Anin. Behav.33: behaviours.Under certain circumstances,even when a 201-205. pelican is present, it may pay for the cormorant to remain Emlem,S. T. andAmbrose, H. w (1970).Feeding interaction of snowy possible egretsand red-breastedmergansers- Auk 87t 164-165. foraging. It is entirely that in this case the 'American cormorant may have been benefiting from fish scaredback Hart, S. D. (1989). while pelican(Pelecanus erythorhyncos\ populations, kleptoparasilism,and other foraging behaviors at to it by the parasitizingpelican. If conditionsexist where Am€rican Ralls Reservoir,southeast ldaho'. (M.Sc. thesis.Idaho increasedcompetition both within and between these two StateUniversity, Pocatello.) 'beating' speciesduring a feeding associationsuch as Hays, H. (1970). Common lerns pirating fish on Creat Gull lsland. occurs, kleptoparasitismmay develop as resourcesand wilson Bull. 82r 99-100. P R. andRohwer, F C. (1996).Confirmation (Brockman and Johnson,W P, Garrettson, foragers become increasingly clumped of kleptoparasitismby Americanwhite pelicanson greatblLre herons. Barnard 1979). Colonial watetbirds19(ht 262 263. King, B. (1966). gulls trying to snatchfood from greatnorthem Further detailed observationsare necessaryto determine divers.Brit. Bnd! 59t 247. if this is a recurring behaviour and under which conditions Munro, J- A. (1949).Studies of waterfowlin British Columbia. either of the birds decides to join or to leave the foraging Baldpatc.Ca4. l. Res. Sect.D.21t 289-294. (1983). and association.In addition, there is the need to quantify the O'Malley,J. B. E. and Evans,R. M. Kleptoparasitism associatedforaging behaviors in Americanwhite pelicans Colonial degree of foraging successor failure for each of the Waterbi ! 6t 126-129. participants in to properly understandthe balance of Palmer.R. S. (1941). A behaviorstudy of the common tem. Proc costs and benefits involved for each member. Since Pied BostonNat. Hist. 12t 1-119. Cormorants and Austalian Pelicans are locally common in Rand,A. L. (1954). Social Feedingin birds Fiediana: zoologv !6. with their common practice of 1-1t. Monkey Mia, combined Schnell.G. D., Woods,B. L. and Ploger,B. J. (1983). foraging close to shore in this area, the study of this foragingsuccess and kleptoparasitismby laughinggulls Art 100: association in Shark Bay is possible. In addition, a 636444. comparative study of the degree and successof parasitism Shealer,D. A., Floyd,T. and Burger,J. (1997).Hosl choiceand success gulls kleptoparasitizingbrown Anim Behav and possible kleptoparasitismbetween sites close to human of and lems Pelicans 53:655-665. oresenceand those in more traditional habitats should be Snow D. w (1958). A Study of Blackbirds' (LondonrGeorge Allen undertaken.This will determine whether this behaviour is and Unwin Ltd.) in fact a natural tactic of the pelicans or has arisen due to T€rshey,B. R., Breese,D. and Meyer,G M (1990) Kleptoparasilism gulls Condor the close presenceof human counterparts. of adult and immaturebrown pelicansby Heerrnan's 92. t0'76 r0'l'l. Vickery, J. A. and Brooke, M. de L. (1994). Tbe kleptoparasitic ACKNOWLEDGMENTS interactionsbetween great and masked boobies on Hendersonislaod, South Pacific- Condor 96t 331-340 We would like !o thank the Departmeltof Conservationand Land walker. D. L (1989). Regionatstudies: Seagrass in Shark bay' the ManaSementin WesternAustralia, the Monk€y Mia Reso( and the 'Biology foundationof an ecosystem.ln of seagrassesia treatise on rangersof Monkey Mia. Thanksalso !o two anonymousreferees who the biology of seagrasseswith specialreference to the Australian reviewedthis paper. region'.(Eds. A. W D. Larkum,A. J Mccomb ard S. A. Shepherd.) (ElsevierScience: Inc. .) REFERENCES ADdercon,J. G. T. (1991).Foraging b€havior of the Americanwhite pelican (Pelemnus erlthorhJncos) in westem Nevada. Colonial wate|birds14| 166 112.