BEHAVIOR An appreciation of oystercatchers Olin Sewall Pettingill, Jr. MagellanicOystercatcher. Photo/O. S. Pettingill.Jr. BlackishOystercatcher. PhotolO. S. Pettingill, Jr YSTERCATCHERSare big, robust, Oystercatchersare so distinct from Mage!lanicOystercatcher (H. !eucopo- boldly markedshorebirds that inhab- othershorebirds that ornithologistshave dus, southern South America and the it long stretchesof the world's oceanic placedthem in a family by themselves; Falkland Islands). The other three are coasts.They are black and white or black and becausethey are so much alike blackor brownishblack: the Black Oys- all over. Their bills are twice the length throughouttheir worldwiderange, orni- tercatcher (H. bachmani, western North of theirheads, and red. Uponsuch pow- thologistshave groupedthem in the sin- America and the Aleutian Islands); the erful and wonderfullydesigned bills do gle genus Haematopus. Within their Sooty Oystercatcher(H. fuliginosus, the lives of oystercatchersdepend. range,however, oystercatchers differ re- Australia and New Zealand); and the Viewedfrom abovethe oystercatcher gionally in coloration and habitat selec- BlackishOystercatcher (H. ater, south- bill is sharplytipped, but viewed from the tion in sucha way that ornithologists ern South America and the Falkland Is- side, the bill tip is squaredoff; thusthe havebeen confounded as to how many lands).In all the speciesthe sexeslook bill is like an oysterknife,suited to open- speciesthere are. alike. ing bivalvemo!lusks-•oysters, mussels, Without reviewing here the lines of Along the Atlantic coast of North andclams--or like a wedge,for prying scientificreasoning and conflicting opin- America as well as in Iceland and New limpets off rocky surfaces. Since the ions, I will state categoricallythat the ZealandI have watchedoystercatchers mandiblesare of equal length, meeting consensusamong most American and occasionally,but neverfor any lengthof firmly at their tips, the bill can pick up Britishornithologists is that thereare six time. So often they were shy and flew foodfrom any flat surface.Furthermore, species.Three are conspicuouslyblack fartheraway whenever I attempted to get thebill, longas it is andrelatively inflexi- and white: the AmericanOystercatcher near them. It was only in the Falkland ble, can probedeeply into sandor soft (Haematopuspalliatus, southeasternand Islandsthat I really becameacquainted soil for wormsand insects.Quite apart southwesternNorth America, the Carib- with oystercatchers. from its capabilitiesfor securinga wide bean, and northern South America); the This archipelagoin the SouthAtlantic, varietyof food, the bill is alsoa formida- EurasianOystercatcher (H. ostralegus, 300 milesnortheast of thesouthern tip of ble weaponfor discouragingpotential Eurasiaincluding Iceland, southernAfri- South America, has two oystercatcher predatorsby painfuljabs. ca, Australia, and New Zealand); and the species,the Magellanicand the Blackish. Volume 39, Number I 3 Both speciesalso inhabitthe coastsof Unlikethe MageilanicOystercatchers, queee, weee, weee, wee, we. When two southern South America. For six months the Blackishfed almostentirely on mol- or morebirds together gave the series, the in the late springand summer of 1953- lusks that they found in abundanceon resultwas a remarkablemedley. Each 1954 and again for five month,in the rocksand ledgesbetween high and low bird. when utteringthe seriesin flight, same austrai seasonsof 1971-1972, my tidelines.Occasionally they flew beyond alternatedmoments of flappingits wings wife Eleanor and 1 were in the Falklands sightof theirhome shores to musselbeds. more slowly. butterfly-like with mo- for b•rd studyand photography.During also frequentedby Mageilanics. When mentsof settingits wingsand gliding. the latter stay we were accompaniedby both specieswere presentat the same My appreciationof each of the two Maurice A. E. Rumboil, my assistant. time--not uncommonly--I never saw Falkland oystercatcherswas attained in Inevitablywe gave both speciesconsid- anyevidence of hostility,but rathertotal separate stages. erable attention, as they were equally disregardof one another. MAGELLANIC OYSTERCATCHERS common, and. becausethey were insu- Boththe Magellanicand Blackishoys- lar, non-migratorybirds more or lessiso- tercatcherswere noisy. The most com- YFroST opportunity towatch these latedin an areawith a sparsehuman pop- moncall of the Mageilanicwas a piping strikinglyhandsome shorebirds for ulation and not subjectto predationby kleee-eeeee,loud and piercingwith a ris- any lengthof time was on December landmammals, they were muchless shy- ing inflection, uttered when flying or 1953, at CarcassIsland. Here, only a --hence more approachable--thanany standing.The call had great carrying shortdistance away on a beach,two for- oystercatchersI had observed elsewhere. power;we could hear it despitewind and agingMageilanics were suddenlyjoined The Mageilanic Oystercatcherswere surf.Among a varietyof othercalls was a by twoothers flying in from afar. At once mostlyresidents of the extensivesandy prolonged,plaintive I,ee-kee-kee-kee of- all fourbegan piping loudly as they drew beachesalong the two big islands, East ten given in flight, somtimesbutterfly- closertogether. What followeddefies co- Falkland and West Falkland, and some of like. Many timesour attentionwas drawn herentdescription. They quick-stepped the largeroutlying islands. The Blackish to a flock of several birds by hearing forward one beside another and occasion- Oystercatchers,on the other hand, re- themas they passedfar out from shore. allybobbed plover-like; they stopped and sided along the many rocky shores The most common vocalization of the faced one another, then turned away, throughoutthe archipelago.Thus, in an Blackish.given when flying or standing, sometimescompletely around to faceone ecologicalsense, the two specieswere was a piping quee-ee, clear and ascend- anotheragain. All this they did with separated,each occupying its own niche. ing but shorterand lesspiercing than the shouldershumped, necks arched, heads Although both specieswere equally Mageilanic's.An additionalvocalization occasionallyjerked up but bills always common,I first thoughtthat the Magei- that I never heard from the Mageilanic pointedstraight down, primariesslightly !anic was more numerous,chiefly be- was a series of loud, ringing, musical lowered,and tails lifted straightup, un- causeat the outsetwe spentmore time on sounds,ascending in a rapid, trill-like fanned. yet clearly showingthe white beacheswhere it wasconspicuous by vir- purrrrrr. followedby high-pitchedqueee basalportions. The entire performance, tue of its black and white plumageand notes. then by slower and descending accompaniedthroughout by pipingcalls orange-redbill. But later. aswe explored •'eee notes that gradually faded from that were variouslysharp, high-pitched. the shoresof rocky headlandsand many hearing. The sequencewas roughly: and discordant, was over in a minute or of the smallerislands with shoreslargely purrrrrr queee, queee, queee, queee, so. The visitingpair movedaway, then of rock, I soon realized that the Blackish Oystercatcherwas probably as numer- ous. My early misconceptionwas due to the bird's uniformly brownish black plumage,which blendedso effectively with thegrayish black rock strata,ledges, and bouldersthat a bird could be easily overlookedunless it moved or unlessby chanceI caughtsight of its scarletbill and stout, pinkishwhite Cuntanned") legs. Mageilanic Oystercatcherssought a w•devariety of foods.On the beachesat ebbingtide they probedfor sandworms andpicked up strandedjellyfish. If there were exposedrocky reefs, they foraged for musselsand limpets. Farther up on the beaches,beyond the normal tides. theyflipped over pebbles and small heaps of washed-upkelp and seaweed to uncov- er and catch whatever insects and crusta- ceansthere might bc underneath.Some- times they moved inland from the beachesto low, grassy wet areas near streams,where they probed, presumably for earthworms. BlackishOystercatcher opening mussel still attached to rock.PhotolO. S. PettingillJr. 4 AmericanBirds, Spring 1985 returned,and all four repeatedthe com- plex d•splay. Again the pair moved away, againthe pair returned,and so on for six separateperformances that were essentiallythe same. Not once did one bird chase another or show the least incli- nationto attack.After the last perform- ance,the visitingpair simplytook off in the direction l¾om whence they had come. I realizedthat I hadwitnessed the "pip- ing ceremony"that Europeanornitholo- gists have frequentlyobserved in their native EurasianOystercatcher and have describedin their publicationswhile ad- vancingtheir ideasof its function. I had neverseen any suchperformance in our AmericanOystercatcher. Again later in January,I watchedMa- gellanicspiping, this time when they were in smallgroups on a beachat New Island.Piping in eachcase was triggered MagellanicOystercatchers performing piping ceremony. Photo/O. S. Pettingill,Jr. as more Magellanicsjoined them. Both the arrivalsand the birdsalready present pipedloudly with billsdown and tails up; a close acquaintancewith Magellanics. the ground(displacement feeding), dab- therewas little moving or turningabout. Within easywalking distance of the little bingat the feathers(displacement preen- In a minuteor so the performancewas farm settlement were two nests about 50 ing), and then standingat intervalswith over. The newcomersstayed, apparently feet aparton a grassyflat ("sheeppas- bills slippedunder