Why the most northerly breeding wader speciesdo not winter in lowland freshwater habitats

A longpreoccupation with a mosttypical High Arctic-breedingwader (Knot) and the writing of wadertexts for theHandbook of the Birdsof the Worldperhaps may haveprimed the author,but readingMatt Ridley's'The Red Queen:Sex and the evolutionof humannature' (Viking, 1993) certainlyinspired the restof thefollowing story..... In a Forum-contributionto the ecologyjournal Oikos, TheunisPiersma recentlyput forward a provocativehypothesis to explainwhy northerlybreeding waders tend to winter in marine environments,and why borealand temperatebreeders winter infreshwater habitats. The hypothesisinvolves parasites, diseaseresistance, and physiologicaltrade-offs between working hard and beingimmunocompetent. The paper is summarised here to invite commentsand elaborationby fellow wader workers.Ed.

Piersma, T. 1997. Do global patterns SevemayaZemlya andthe New Siberian breedingspecies winter predominantly of habitat useand migration studies Islandscontain sizeable populations only in marine environments; boreal/low co-evolve with relative investments in of RingedPlover, Grey Plover, arcticbreeding species winter mainly in immunocompetencedue to spatial Tumstone,Knot, Sanderling,and Purple freshwaterhabitats (Table 1). A few variation in parasite pressure?Oikos Sandpiper.Strikingly, all thesespecies speciesfell betweenthese two extremes 80: 623-631. are confined to marine shores outside the andthey occupymarine as well as breedingperiod. Conversely,most of freshwaterhabitats during the The diversityof breedingshorebirds is the tringinewaders that breed in the nonbreedingseason. The samepattern highestin subarcticand arctic regions northern boreal and subarctic climate wasfound in congenericpairs of plovers but the mostnortherly and climatically zones, winter in inland, freshwater, and sandpipersin which at leastone extremeparts of the Arctic are inhabited wetland habitats. specieswas restricted to (high) arctic by few species.The CanadianQueen breedinghabitats. Ten of the 11 species- Elizabeth islands, North Greenland and Indeed,in the sandpipersubfamily pairsshowed the suggestedassociation the northernedge of Taimyr Peninsula, Calidridinae,high arcticand alpine betweenarctic breeding and coastal Table 1. Interspecificassociations between the typesof breedingand wintering habitats of sandpipers winteringhabitats (Table 2). Why would (subfamilyCalidridinae). The two species(Calidris bairdii and C. melanotos)mainly wintering in alpine this be so? freshwaterenvironments in the Andes(and sometimesalong seashores) were classifiedconservatively as winteringin 'mixed'environments. The sortingof the sandpiperspecies among the varioustypes of breeding Althoughhigh arctic tundra and marine andwintering habitat was significantly different from random (Chi-square test, XZ=20.5, df=4, p<0.001). shores seem to have little in common, bothmay be relatively'healthy'. In fact, Breeding habitat Wintering habitat thereis quitea lot of evidencethat Marine Mixed Freshwater marine,arctic and alpine environments 9 1 0 High (/Low) arctic andAlpine have reducedloads of parasites Low (/High) arctic 4 2 3 comparedwith borealand temperate Boreal and Low arctic 0 1 4 lowland freshwaterhabitats. Thus, in

Table 2. Pairwisecomparison between members of thesame or closelyrelated genera of ploversand sandpipers (Charadriidae and Scolopacidae). Each example consistsof a speciesthat breeds in the arctic,compared with a randomlychosen congener breeding more to the south.The specieswintering in moremarine habitatsreceived an asterisk.The generaLimosa, Tringa and Calidris occur twice in the tablewith examplesfrom the Palearctic-Africanand American flyways, respectively.A ratioof 10 out of 11 is statisticallysignificantly different from a randomration of 0.5 (two-tailedbinomial test, p=0.001). Note thatthe difference evenremained significant if a genuswas counted only once(7 of 8; binomialtest, p=0.03).

Northernmost breeder More southerly breeder Grey Plover Pluvialis squatarola* Golden Plover Pluvialis apricaria RingedPlover Charadriushiaticula* Little RingedPlover Charadrius dubius Long-billedDowitcher Limnodromus scolopaceus Short-billedDowitcher Limnodromusgriseus* Bar-tailedGodwit Limosalapponica* Black-tailed Godwit Limosa limosa Hudsonian Godwit Limosa haemastica* Marbled Godwit Limosafedoa Whimbrel Numeniusphaeopus* Curlew Numeniusarquata GreenshankTringa nebularia* Marsh SandpiperTringa stagnatilis LesserYellowlegs Tringa fiavipes* GreaterYellowlegs Tringa melanoleuca Little Stint Calidris minuta* Temminck's Stint Calidris temminckii White-rompedSandpiper Calidrisfuscicollis* LeastSandpiper Calidris minutilla Red/Red-neckedPhalarope Phalaropusfulicaria/lobatus* Wilson'sPhalarope Steganopus tricolor 19 the former habitattypes, waders could in seashores)small investmentsin diversity(e.g. MHC genecomplex) principleallocate their energeticand immunodefence mechanisms are might be of little consequence.For nutritional investments to sustained sufficient. However, as such habitats are example,such species might quite easily exerciseand thermoregulation rather few andfar between,this lifestyle surviveextreme population crashes thanto build-upand maintain disease necessitateslong and demanding duringclimatic intervals with large resistance. migratoryflights in the courseof an habitatloss, something that may have annualcycle. Also, the chosenhabitats happenedrepeatedly to Knots. On the basis of these associations are oftenenergetically costly to live in. betweenthe characteristicsof breeding and winteringhabitats and other In summary,waders restricted to Theunis Piersma, Netherlands Institute comparativeevidence (low apparent relativelyparasite-poor habitats such as for Sea Research(NIOZ), P O. Box 59, immunocompetencein marinewintering tundra and seashores would not invest in 1790 AB Den Burg, Texel,The species,and very high levelsof energy disease resistance. This would allow for Netherlands,and Centrefor Ecological expenditureand fast growthin wader high ratesof energyexpenditure without and EvolutionaryStudies, University of chicksin the High Arctic), a trade-off detrimental effects on survival. The lack Groningen,P O. Box 14, 9750 AA between investments in immuno- of parasiteswould enable very high rates Haren, The Netherlands (E-mail: functioning(disease resistance) and of energyexpenditure before and during [email protected]). sustainedexercise (migration, non-stopmigration flights of 3,000- thermoregulation)is suggested.For 8,000 km, and for maintenance in cold speciesrestricted to parasite-poor and exposedhabitats. Additionally, loss habitats(high arctictundra, exposed of immunodefence-relatedgenetic

Wetland Connectivity and Waterbird Conservation in the Western Great Basin of the United States

SusanM. Haig, Forestand RangelandEcosystem Science Center, U.S. GeologicalSurvey, 3200 SW JeffersonWay, CorvallisOR 97331, USA [email protected]. EDU

Lewis W. Oring, Departmentof EnvironmentalResource Science, Universityof Nevada, 1000 Valley Rd., RenoNV 89512, USA

INTRODUCTION waterbird conservation in the Western the first regionalplanning effort for the GreatBasin. Over 100 participants National Plan. As scientists,managers and landowners, spentone day listeningto talks from we have come to realize that to best waterbird researchers that focused on Western Great Basin wetlands stretch understandthe local andregional value multi-scale habitat use and movements from MalheurNational Wildlife Refuge of individual wetlands, we need to take a of birdsin the region. From American in centralOregon to Mono Lake, broadgeographic, taxonomic, and Avocets Recurvirostra americana to California. This stringof desertoases managementview. In December 1994, a White Pelicans Pelcanus provideshabitat to hundredsof symposiumwas held in Reno,Nevada erythrorhynchoswe learnedof thousandsof waterbirds(shorebirds, that addressedthis topic for shorebirds phenomenalintra-season movements wadingbirds, waterfowl, etc.) by bringingtogether researchers and throughoutthe Basin and the value of throughoutthe annualcycle. Over 48% managersfrom the WesternGreat Basin collectingdetailed data of this naturefor (78/161) of North American waterbird to discuss shorebird research and representativewaterbirds. We learned speciesand 63% (29/46) of North managementin the region(Reed et al. also about the National Shorebird American shorebirdspecies commonly 1997, International Wader Studies9). In ConservationPlan and spentthe next occur in the area. Furthermore, over February 1998, a similar,but broader, day in discussiongroups where future 43% (9/21) of non-Arcticbreeding symposiumwas held in Bend, Oregon researchand management priorities shorebirdspecies occur as breeders. that addressedwetland connectivity and were outlined. These discussions were Constantpressures for multipleuse