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					                                          BIRDS
                                  ENDANGERED

                                  N.J. Collar
                                       lntemdtiotal
                                  BirdLife




 t. Introduction                                                                      tions of lessthan 10,000mature individuals. The Philip-
tI. The Identification of EndangeredBirds                                                                                            the
                                                                                      pines, Indonesia,Brazil, and Colombia possess most
I . Trends and Factors in the Endangerment of Birds                                   significant  proportions of endangeredbirds. Tropical
lv. Approaches to the Conservation of Threatened                                      forest loss is the greatest threat, but there are many
    Birds                                                                             other reasonsfor elevatedvulnerability (through range
                                                                                      restriction, occurrenceon islands,use ofrestdcted habi-
                                                                                      tat. etc.). Remedial actions include detailed research
                                                                                      and documentation, site and habitat protection, and
                            GLOSSARY                                                  intensive multilaceted managementprograms.

biological species concept Concept of a species as a
   population or series of populations that are repro-                                                I.INTRODUCTION
   ductively isolated from other groups, as well as the
   degree of morphological similarity.                                                Endangerment is the condition in which a speciesor
endangerment Condition in which a sPeciesis at risk                                   subspeciesof animal or plant is at risk of extinction.
   oI extinction.                                                                     The nature of the impending extinction may be local,
phylogenetic species concept Concept of a sPeciesin                                   national, or global. There is no vocabulary to differenti-
   *'hich speciesJevelidentity is determined by men-                                  ate between these conditions; as a consequ€nce,there
   bers sharins distinct characteristics.                                             is often confusion over appropriate priority levels. A
                                                                                      trend to use extirpationto indicate nonglobal extinction
                                                                                      brings its own problems, since the active verb extirpate
                                                                                      is sy'non)-mous with eradicate;thereis also the problem
ENDANGERED BIRDS ARE DEFINED CHIEFLY AT                                               that disappearing subspeciesof species may be both
THE SPECIESLEVEL (although the definition of "spe-                                    extinct 4r1dextirpated (extinct as taxonomically distinct
cies" remains contentious), and at the global and na-                                 forms, extirpated as representativesof a hiSher taxo-
rional levels. New global criteria apply thresholds on                                nomic unit). This article conc€ntratesprimarily on bird
decline rate, population size, and range size to ldentify                             speciesat risk of global extinction, but nationally and
endangerment. Some I 10,6 the world's avifauna are
                            of                                                                                                          are
                                                                                      locally endangeredforms, including subspecies, also
at risk, but altogether 20% of species give cause for                                 consideredi so extiry*ted is here used to  mean locally
concem. Most endangered birds (70%) have popula-                                      extinct. The terms mdangered, threatened, and. at rish

Enq(lopeaia o! Biodrenitt, volude 2
Copyright   O 20ol by Acad.nic   Press. All rights of reProduction   in any tom   r6erved                                                   395
396                                              E N D A NG E R E DB I R D S

are commonly used interchangeably; endangeredis                  where very minor differences (sometimes biochemical
prevalent in U.S. usage,but IUCN/The World Conser-               only, and certainly not used to recognize even subspe-
vation Union status categories\se threateted.as a ge-            cies) may or may not be regardedas suffrciently distinct
neric term ^nd Endangered (with a capital E) for a               and consistent to admit species-level   status, so that no
                                             is
particular status. ln this article, endangered. preferred,       final number ofavian speciescan be even approximated.
exceptin contexts involving the IUCN threat categories.             This debateis important, not leastbecause    biological
                                                                 diversity is directly at stake.Someyearsago th€ Birdlife
                                                                 Red Data Book program eliminated subspecies       from its
          II. THEIDENTIFICATION
                             OF                                 concern, on the basis that there were simply too many
               ENDANGEREDBIRDS                                   to document and that specieshad to take prioriry. This
                                                                decision, made with the knowledge that many threat-
      A. Taxonomy theldentification
                and               of                            ened subspecies    will benefit from site managementfor
                                                                threatened specieswith which they are sympatric, still
               Target
                    Units                                       tends to exposesome subspecies,      especiallythose with
 ln general,decision makers look to sciencein two ways          small ranges and therefore with relatively constrained
 for help in establishing pdorities in speciesconserva-         populations, to the vagariesof deteriorating global con-
 tion: the first is the degreeof a taxon's risk o[extinction,   ditions. Unless a country is as wealthy as the United
and the secondis the degreeofits evolutionary differen-         States,whose legislation embracessubspeciesand in-
 tiation. Many people are surprised that these aspects,         deed populations, or has little or no other biological
particularly the second, remain hard to assess.Ever             heritage in which to invest (for birds, Barbadosis one
since the passing of the United StatesEndangeredSpe-            such). the chances of intervention on behalf of these
cies Act, the term "endangered species" has become              forms are relatively low.
widely used in popular and indeed jocular English par-              Nevertheless,subspeciesare far less stable as taxo-
lance; so it seems extraordinary that debate still rages        nomic entities than are species,and are easily erected
over what a speciesis. Nonetheless,its definition is a          and just as easily subsumed (prior to 1950 at least two
pewasive problem, and the profile of this issue will            museum ornithologists, Oberholser and Koelz, each es-
increaseas more morphologically distinct, local forms,          tablished over I00 subspeciesin the course of a single
currently considered subspecies,come under pressure             paper!). Becauseof this, they are generally unwelcome
from human development         activilies.                      in law, which requires widespreadlong-tern agreement
    When considering closelyrelated taxa in which there         on taxonomy to be able to function. Consequently,
is no geographical contact, and therefore no test for           speciesrather than subspecies     are the units of concern
reproductive isolation (the key criterion under the prev-       in most national and international legislation.
alent Biological SpeciesConcept or BSC), taxonomists                Partly perhaps as a consequenceo[ this, many omi-
are compelled to rely on the degreeoftheir morphologi-          thologists seemwilling to countenancethe steady,con-
cal similarity to judge, subjectively, whether they are         sistent "unlumping" of many forms, on the basis of
conspecific or not. Among birds there are thousandsof           multiple character differences extending beyond mor-
such cases,in part becauseflight has allowed them to            phology to voice, behavior, and even habitat. For con-
colonize so many offshore and oceanic islands, where            servation purposes this process needs to be expedited
they have evolved features that distinguish them at             to ensure that specific identity is not bestowed too late
some level Irom continental or other island stock.              forintervention. However, the elevationof many weakly
    Some influential museum-basedomithologists have             distinct forms to species level may actually make the
recently advocateda narrow phylogenetic speciescon-             identification of conservation targets harder, for if re-
cept (PSC),which bestowsspecies-level         identity on any   sourcesare insufficient to support all the resulting en-
population whose members fully share distinct charac-           dangered species, many deserving cases (in terms of
ters,irrespectiveof hybrid zones.Many ofthese popula-           their evolutionary distinctiveness) might be lost amid
tions currently have taxonomic standing as subspecies,          the compedng claims o[ virtual look-alikes.
and proponents of the PSCexpect its adoption to cause
a doubling of the number o{ avian species, to about                             and
                                                                         B. Scale theldentification
                                                                                                  of
20,000 from the roughly 9500 in current usage.How-
ever, BSC supporters contend that, rather than clarify-
                                                                                 Target
                                                                                      Units
ing the status of disjunct populadons, the PSC shifts           Birds can be endangeredat the global, broad regional
the difficulty to a yetmore complex and subjectivelevel,        (e.9., subcontinental), national, narrow regional (e.g.,
                                                E N D A N G E R E DB I R D S                                        397

provincial), and local levels. It is entirely legidmate for     recently inaugurated Convention on Biological Diver-
countries and specialist interests to seek to "red-list"        sity. Although the Convention has a supposedlyglobal
(i.e., list as endangered)bird taxa at thesevarious levels'     remit and ovewiew, it has devolved responsibility for
although as the scalebecornes    smaller, the various legit-    actions in defenseof biodiversity to national agencies
imate causes    may, theoretically at least,begin to conflict   as framed by natiotal perceptions. Parties to the Con-
with one another. However, decreasingscale is widely            vention thus sornewhat unfortunately run the risk of
acceptedas correlating with decreasing      Priority, so con-   focusing only on elements of their natural Patrimony
flicts of interest are unusual.                                 that they regard as relevant, at the expense of species
     Global endangermentis the most important priority          identified through intemational perspectives.
level, since total extinction is a far worse risk than any
other form. ln th€ past 35 years or so, global endanger-                                           of
                                                                        C. Criteria theIdentification
                                                                                  for
ment of birds has been registered principally through                                  Units
                                                                                  Target
the RedDataBook program ofthe lnternational Council
for Bird Preservation(now Birdlife lntemational). This          Under protocols still being developed by IUCN/The
program, acceptedby IUCN/The World Conservation                 World Conservation Union, the global redJisting of a
Union as the official source of globally threatenedbird         taxon may occur only if its conservationstatusisjudged
listings, has developedinto a long-term, continent-ori-         to satisfy at least one of a set of universal quandtative
ented project to created€tailed profiles of every endan-        criteria (IUCN Species Suwival Commission, I99't).
gered species (Collar and Stuart, 1985; Coll^t et al.,          Since a species can only become extinct by decreases
 1992; Collar et al., 1999), based on the rationale that        in population and range size, these criteria set thresh-
all information relevant to a species's conservadon             olds on these parametersas well as on decline rate by
should be included. This in turn has led to the need            which to measureeligibility for and degreeo[threatened
 for abbreviated global listings (Collar et aI , 1994).         status. In IUCN terminology, the word thredtenedmeans
     The speciesthat have found their way into these full       what has hitherto b een called otdangered, whereas "En-
 and abbreviated Red Data Books are normally found              dangered' denotes a specific conservation status.
 on national "red lists," but not always at the expected             ln crude form, the criteda stipulate that, to qualifu
 priorit) level, owing to the various algorithms that non-      as threaten€d,a speciesmust possess total population
                                                                                                        a
 global assessment    tends to involve. Thus an apparently      (A) declining at a rate (projected or past) of 20% over
 Iogical ranking system in the 1984 South AJrican Red            I0 years or three generations,or (B) within a range of
 Dat.1Book; Birds resulted in widespread and common             less than 20,000 kmt and decLining,or (C) of less than
 speciessuch as EgJptian Vultu:'e (Neophronpercnopt'             10,000 mature individuals and declining, or (DI) of
 enrs) and House M artin (Delichonurbica)-both found             less than 1000 mature individuals, or (D2) within a
 in Europe, the latter in huge numbers-coming out                range of less than 100 kmr. SPeciesmeeting any one
 higher (2/102 ar:.d6/102, respectively) than the top-           of these criteria qualify as threatened with the category
  ranking globally threatened South African endemic              Vulnerable; nested thresholds qualify species for the
  Rudd's Lark (HeteromiraJrq ruddii)(22/ 102) .                  categoriesEndangeredand Critically Endangered.Sub-
     Much more frequently a speciesis declared nation-           speciescan be subjected to the same criteria, but this
  ally endangeredwithout being globally endangered,al-           may result in the curious circumstancewhere all races
  rhough the issuesat stakemay sometimesbe so momen-             of a species qualify as at risk (e.8., all five races of
  tous that global endangerment is often assumed.This            an island specieswith declining populations of under
  is the case with the Houbara (Chlamydotis undulata),            10,000) but the speciesitselfdoes not (total population
 judged by many to be unsustainably exploited by Gulf            still above 40,000).
  State hunters in most of its range and yet on Central               The general experiencewith birds, almost certainly
  Asian evid€nce still outside the IUCN criteria thresh-         as with all animals and plans, is that populations tend
  olds. Similarly, the Spotted Owl (Strir occidefillis) is        to be significantly underestirnated: for example, one
  an endangeredspeciesunder U.S. law, but it still misses         observeron the N€w Caledonian island of Uveajudged
  the IUCN criteria because its populations north and             there to be 70-90 Uvea (Horned) Parakeets (Eunymphi'
  south o[ its U.S. range render it unlikely to die out           cus (comutus) uvesnsis)in 1993, but more intensive
  within a relatively short time frame.                           fieldwork later that year yielded a formal estimate of
      However, clearly the most important red list after the      617 'r i79- Similarlv, a CAMP (Conservation Assess-
  slobal list must be at the national level, and somewhat         ment and Management Plan) run by the Captive Breed-
  iurprisingly this emphasis has been increased by the            ing SpecialistGroup of IUCN in 1992 suggesteda total
398                                           E N D A NG E R E DB I R D S

 population oI som€ 5000 Tanimbar Corellas (Cacatua           over, a further 66 (I%) specieswere then listed as Data
 goffni), whereas analysisof quantified data from field-      Deficient and 875 (9%) as Near-Threatened, so that
 work that same year produced an estimateof 300,000-          altogether over 20% of all bird specieswere identified
 400,000 birds. Consequently,liss of threatenedspecies        as being of some global conservation concem. The ma-
 cannot be expected to remain shbl€: while some will         jority ofthreatened species     were classifiedasVulnerable
 be added over time as their situation deteriorates or        (7O4,63ok),w1th235(2196)Endangeredand 168 (15%)
 their taxonomy is revised. others will be removed as         Critically Endangered.
 their true status is revealed.                                  The commonest criterion triggered by threatened
     In 1988, 1030 bird specieswere idendfied as at risk     birds was C, which combines small population
 of extinction. In 1994, this figure, based on the new        (<10,000) with significant decline. As many as 764
 IUCN criteria, rose to lll l. It was not, however, the      species(approaching 70o6)of all rhreatenedbirds were
 case that 8l specieswere added to the 1988 comple-          judged (or, under the precautionary principle, thought
 ment. ln fact only 816 specieswere common to both           likely) to fulfill this criterion; thus 8o/o
                                                                                                        ofall bird species
 lists. The 214 disappearances     from and 295 addirions    are known or suspectedto have dangerouslylow popu-
 to the 1994 list largely resulted from new "pioneering"     lations. The other four criteria proved to be rather
 knowledge (involving new areasor new identification         evenly dist buted: A (rapid decline) and B (small range
 insights) rather than from "monitoring" updates that        with significant decline) were triggered b1' around 400
 disclosed a clear trend. Exploration is thus still the      species each, with somewhat smaller numbers trig-
strongest biological data source, and "rare" species(for     gering D1 (very small population) and D2 (very
which see Kunin and Gaston, 1998) sometimes prove            small range).
 to be relatively common in some part of their range,            The new IUCN criteria attach hlporhetical probabili-
or in some previously uninvestigated habitat. Conse-         ties o[ extinction to the differenr caregoriesof threat,
quently, attempts to predict future extincdon rates us-      on which basis400 speciesma1'be expectedto become
ing changes in red lists have been premature: the            extinct.without remedial       acrion,in rhe comingcentury;
changesin question are not real-world events (Crosby         however.it will take 1750 years for 900,6 the llII
                                                                                                              of
et 4.1.. 1996).                                              listed threatenedspeciesto disappear.Comparison with
     A degree of red list stability derives from some spe-   the 1988 listing allo*,ed three differ€nr listing recruit-
cies being destined to remain endangeredin perpetuit)..      ment rates to be tested on rwo models, indicating that
This is b€causeof their irremediably small ranges or         q'ith current trends between 400 and 1200 speciesof
populations (a circumstance that has made the criteria       bird may die out within the nexr 100 years,with a rime
unpopular in some quart€rs,since no active threat need       to extinction for half the planet's avilauna (ca.4850
exisl to lrigger the listing). These are species-avian       species) of 800-2800 years (Crosby et al., 1996). Al-
examples including the tava Gull (Larus Juliginosus),        though these figures are less pessimistic than other
with 300-400 pairs maximum, and the Tinian Monarch           recent estimatesderived from less robust data, human
(Monarcha ta.hatsuh4s4e), an island of less than I00
                             on                              pressureson the environment will only increasein the
km2 despite its estimared 40,000 individuals-for             foreseeable  future, so these extinction rates will proba-
which the price of survival is eternal vigilance.            blv orove much too conservative.
    Appropriate criteria for use at the national level are
still under development by IUCN; meanwhile, a good                B. Globally        Birds:
                                                                            Threatened Regions,
model is that of Avery ef al. (in Coulson and Crock-
ford, 1995).
                                                                                  Habitats
                                                                          Countries,
                                                             The majority of threatened bird species occur in Asia
                                                             and the New World, with relatively few in Africa. The
      III, TRENDS FACTORS THE
                AND      IN                                  top ten countries for the high€st numbers of threatened
           ENDANGERMENT
                     OFBIRDS                                 speciesare lndonesia (104), Brazil (I03), Philippines
                                                             and China (both 86), lndia (71), Colombia (62). Peru
               Threatened in 1994:
     A. Globally         Birds                               (60), Ecuador (50), United Sutes (46), and Vietnam
      Numbers,         and
               Criteria, Extinction                          (45). Asian countries predominate in rhis list: the
                                                             United Statesranks high becauseof its Pacific territor-
              RatePredictions                                ies. The highest African countdes, ranking 2lst and
The l11l bird species judged to b€ at risk of extinction     22nd, are Tanzania (30) and Madagascar(28).
in 1994 representedI l% of the world's avifauna.Mor€-           Prio ty countries might be selected on rhis basis,
                                               ENDANGERED IRDS
                                                        B                                                             399

but severalfurther filters can be applied. Because  species   location varied from year to year, that is, that were
in the higher categoriesof threat are likely to become        patchy in both space and time. Human settlement of
extinct sooner, a reranking involving just those 403          the east and center of the North American continent
speciesthat are either Critically Endangeredor Endan-         fragmented the native forests to the point where the
gered .vieldsa top ten of Brazil (47), Philippines (45),      lapsein both time and distancebetween masting events
Colombia (31), United Sates (25), lndonesia and Mex-          simplybecame too great.Despite the settlers'prodigious
ico (20 each), Peru (18), and Vietnam, Ecuador, and           slaughter of birds, which has always been blamed for
.{rgentina (16 each). Using this category, the emphasis       their disappearance,it aPpearsthat it may have been
shifts dramatically to the New world.                         their axes, not their guns, that caused the loss of their
    A further filter involves only those speciesfrom the      quarry; the last wild birds very possibly st4rvedto death.
preceding analysisthat are nationally endemic, thereby            An equally celebrated   North AmericansPecies,       Per-
indicating the degree of "ultimate resPonsibility" that       haps still extant, is the Eskimo Curlew (Numenius bore'
falls to thesecountries as their most urgent bird conser-     clis), which, like the PassengerPigeon, used to be
vation task. The Philippines (40) emerge far ahead of         hunted in phenomenal nunbers in the nineteenth cen-
Brazil (32). itsell far ahead of Colombia (24), United        tury and likewise never recovered after the slaughter
States (17), Mexico (13), Indonesia and New Zealand           finally abated.It seemslikely, however, that the loss of
(12 each),Australia (II), Madagascar         (10), and Peru   its Argentine grassland wintering grounds and North
 (9). Although it was fairly obvious from the first analy-    American prairie spring stopover sites was to blame.
sis, given their small land area, that the Philippines        Loss of stopover habitat is beginning to supplant hunt-
would be a priority area, this refined analysis offers        ing (never a convincing case)as the best explanation for
startling evidenceofthe critical imPortanceofthe coun-         rhe virtual disappearance the closely related Slender-
                                                                                          of
 try in terms of avian biodiversity and its impending loss.   billed Curlew (N. tenuirostris),which breedsin westem
    The catastrophic erasure o[ forests from the planet        Siberia and migrates southwest to the Medit€nanean
in the course of the twentieth century means that most        basin, almost certainly using the once extensive east-
 threatened birds are (mostly tropical) forest dwellers;       west Russian steppesalong the way.
 the only surprising thing is that the figure is as low as         Other notable examples of this space/time vulnera-
 65%. Wetland species account for 9%, scrubland for           bility include the Thick-billed Parrot (Rhynchopsitta      p4'
 another 97o, and grassland for 6%. The reladvely low          chy rhyncha), P urple-winged Ground-dove     (Cl ar at is go-
 forest representation can be explained in pan by the          deJnda), Andean (Phoenicopterus      andinus), and Puna
 fact that the largest tracts o[ forest, in Amazonia, the      Flamingos   (P. jamesi), Lesser Florican (Sypheotides iv
 Congo basin, and Borneo, are-despite the destruction          dica), and Resplendent Quetzal (Pharomachrus moc-
 visited upon them-still too extensive,and the species         inno). The parrot shows the sarnetrait as the Passenger
 they contain too widespread, to have resulted in more         Pigeon,since it is dependenton pine seed,a notoriously
 than a handful of listings from these areas.                  unpredictable resource. The speciesis nomadic, but as
                                                               its native pine forests in Mexico's Sierra Madre are fur-
                                                               ther fragmented, there is a serious danger that a cone-
               of         in Birds
       C. Causes Endangerment                                  crop failure will leave the last populations "stranded"
Endangered birds suffer from a range of different              too far from food for any to suruive. The ground-dove
rhreats. Some 52olo them are affectedby habitat loss
                    of                                         specializeson the seedsof forest bamboo in southeast
rnd degradation(although this figure is almost certainly       Brazil. So much forest has been destroyed within its
higher: indeed, low-level and hence unreported habitat         range,and bamboo seedset so temporally patchy, that
                                                                                            is
loss could probably safely be indicated for the other          the specieshas become one of the rarest in the country.
48%); this theme is explored in the following para-                The flamingos move between lakes in search of ap-
graphs. The next most important threat is simPly re-           propriate conditions (which shift over tim€) and are
striction of range or population, involving 23% of all         therefore exposed to the possibility that human damage
threatened birds. Hunting afflicts 8%, introduced spe-         to even a small number of sites may one day leave
cies 6%, and trade 3%.                                         the species with nowhere to go. The florican selecs
   Until recently the notion that habitat lossv/asimpor-       different grassland sites from year to year in rMestem
tant in the demise of the Passeng€r   Pigeon (Ectopist€s       India, depending on the effects of local rainfall. Grass-
migratoius) had not been entertained, but Bucher               land is under enormous human pressure in India, and
(1992) showed how the specieswas a specialiston seeds          conserving tracts that may be empty of birds for several
produced in masting eventswhose scaleand geographic            yearsat a time isnot a simPleproposition. Post-breeding
400                                                    B
                                              ENDANGERED IRDS

 quetzals are now known to make complex short-dis-            bonia cancellata), Po\.nesian Ground-dove (Gallico-
  tancemovements to severaldifferent aleas.so that manv        lumba erythroptera), Seychelles Paradise-flycatcher
  more tracts o[ forest than one or two may be needei          (Terpsiphone comina), and Rarotonga Monarch (Po-
  to ensure the long-term survival of viable populations      morea dimidiata) are a few of the Critically Endangered
 of this species.                                             birds whose fate is directly linked to the invasion o[
     ln Australia, many birds have been affected by hu-       their islands by rats. ln some cases where cats have also
 man alrcradon of the natural fire regime. The Paradise       been introduced, it is not clear which predator is the
 Parrot (Psephotus pulcherimus) almost certainly be-          greater culprit, and these affected speciesoften live on
 came extinct (it may conceivably survive somewhere)          larger islands where very little can be done to help. The
 owing to new buming pattems that suited livestock but        New Caledonian Rail (Gallirallus lclresncyus), Cuba's
 not the grasseson whose seeds the parrot subsisted.          Zapata Rail (Cyanolimnascen/erai), the SamoanMoor-
 Similar problems afflict the food supply of the Golden-      hen (Gqllinula sylvestris), and virtually the entire en-
 shouldered Parrot (P, chrysopterygius)   and the habitat     demic avifauna of Hawaii (the linle of it that survives,
 of the Noisy Scrub-bird (Atichomis clamosus).                but notably the honeycreepers,    Drepanididae) are good
     The reasonwhy restriction of range ranks so highly       examplesof this uncertainty and impotence. Cats alone
 in the list of thr€ats is becauseany cause of decline is     are responsible for the plight of some species,such as
 likely to affect the endre speciestoo quickly for human      Townsend's Shearwater (Puffnus auricularis), Socorro
 intervention to help. Such speciesare often restricted       Dove (Zenaido.   graysoni), and the Marquesan Ground-
 to islands, and when those islands are oceanic, the          dove (Gallicolumbarubesrens).    Mongooses,which were
 birds have usually evolved in the absenceofcontinental       often released to devour rats or control snakes, are
 pressuresfrom mammalian predators.As a consequence           major threats to speciessuch as Hawaiian Duck (Ancs
 they are behaviorally and physically adapred in ways         w_yvilliana) and St Lucias Semper'sWarbler (Leuco-
 that leave them highly vulnerable when continental          peza semperi)   .
 predators become established within their ranges,               Ancient lakes, like oceanic islands, often harbor en-
 through either the direct or indirect agencyo[ humans.       demic faunas and floras that are highly susceptible ro
     These behavioral adaptations are not degenerative.       exotic introductions. Among the birds, the grebe family
 The Dodo (Raphus cucullatus) was given its name from         Podicepitidae has been particularly hard hit, with the
 the Portugueseslang for "stupid," doido.But island ani-     Alaotra Grebe (Tachybaptus                 of
                                                                                            ruJolavatus) Madagascar
mals that are €ntirely tame, or that nest in what to         and Junin Grebe (Podiceps taczarowshit) of Peru close
human eyesare ludicrously undefended places,or that           to extinction; the Aritldn Grebe (Podylimbus gigas) of
have lost the function of their wings ar€ not evolution-     Guatemala and Colombian Grebe (Podiceps atdinus)
ary failures. On the contrary, theseseeminglydisadvan-       have already vanished.
tageous attributes are th€ result of continuing evolu-           Linear water bodies may similarly expose certain
tionary pressures. Wings cost en€rgy to carry and            speciesto extinction risks from a single event or sedes
maintain, and in the absenceof predators they offer no       o[ events: Scaly-sidedMerganser (Mergus squamatus),
retum on the investm€nt in such energy.Shynesscosts          Brazilian Merganser (M. octosetaceus),     Wrybill (Anar-
its possessorsdearly if less shy creatures have more         hynchus Jrontalis), Rufous-throated Dipper (Cinclus
time to exploit whatever resource is at stake. Nesting       schulzi), and Luzon Water-redstart (Rhyacomis bicolor)
in inaccessibleplacesis needlesslyexpensivei[ there is       are all vulnerable in this way. Moreover, species that
no risk in nesting on the ground in the open. Moreover,      concentrate in a small area for even part of their life
the relatively stable conditions on tropical islands tend    cycle may be abnormally exposedto danger. For exam-
to promote marked K-selected traits (e.g., slow repro-       ple, the entire world population of Ascension Frig-
ductive rates).So the very things that render island birds   ^tebird.(Fregato.  o.quila)breedson a single stack smaller
so vulnerable to aggressive,fast-breeding,continental        than a municipal parking lot- Even birds that are briefly
animals have actually been selectedJor through nar-          drawn to individual fruiting trees are liable to suffer:
rower, often intraspecific competition.                      as many as 40 VisayanWrinkled Hombills (Aceroswal-
    Most avian extinctions since 1600 have been on is-       deni) were shot in a single tree over the course of a
lands (King, in Moors, 1985), and a significant number       single day in October, 1997,an event that quite possibly
of threatenedbirds today are island species.The impact       killed 50% of the population.
of rats has been and remains massive(seeAtkinson. in             The foregoing examples represent "spatial" threats.
Moors, 1985): Magenh Petrel (Pterodromamagentae),            Other threats are better characterized as "temooral-"
Zino's Petrel (P. madeira), Tuamotu Sandpiper (Proso-        involving a seemingly innocenr event whose conse-
                                              ENDANGERED IRDS
                                                       B                                                          40t

quencescannot be remedied by the time they become           ger (Conothraupis mesoleuca, Brazil), Cherry-throated
apparent.Ne*'Zealand's Kaka (Nestorm endionalis)and         Tanager(Nemosiarourei, Brazil),Ibadan Malimbe (Mal-
Yelloshead (Mohoua ochrocephala)       face enormous dif-   imbus ibadanansis,southem Nigeria), and lsabela Oriole
ficuhies no$'that introduced waspscomPetewith them          (Oriolus isabellae,Ltzon, Philippines) . All are bafflingly
[or honevde*. an extremely important foodstuff (breed-      rarer-some are known only by a single museum speci-
ing successin the Kaka is directly correlated with hon-     men-than rnight be inferred from the habitat appar-
e\.deq inrake in the previous autumn). The white-           ently availableto them. Unidentified factors must afflict
hcaded Duck (Oxyuralzucocephala)       faceslong-term ex-   them all, and clear|y sometimesnatural causes may be
rincrion through hybridization with its New World           in play, particularly unseen ones such as diseasesand
counterpart, the Ruddy Duck (O. jamaicensis),which          infestations(seeMay, in Coulson and Crockford, 1995),
becameferal in Britain in the 1960s and is now spread-      which are known to afflict the lphis Monarch (Pomates
                                                                                                                    -fhe
ing into its range. In both casesthe costs and logistics    iphis) and Gouldian Finch (Erythrura gouldiae).
o[ eradication    are too great lo consider.                safestassumpdon in cases inexplicable rarity, at least
                                                                                        of
    Sometimes threats come not from exotics but lrom        on condnents, is that habitat degradation or loss is in
natives expanding their ranges,often owing to human         some way involved.
modifications of habitat. The spread of cowbirds (Mo-
lothrus) through the Americas and the Caribbean is
particularly worr)4ng. Birds such as Kirtland's Warbler                   IV. APPROACHES       TOTHE
 (Dendroica hirtlandii) and Black-capped Vireo (Vireo                        CONSERVATION         OF
 atricapillvs) need constant-effort prograrns to r€duce                     THREATENED         BIRDS
cowbird brood-parasitism to tolerable levels. Similarly
 rhe spread through the Caribbean of the Pearly-eyed                                     and
                                                                           A. Research Synthesis
 Thrasher (Margarops fuscatus), a nest-hole competitor,
 has been viewed with alarm by the Puerto Rican Ama-        The primary consewation need of an endangeredspe-
 zon (Amazonavittatd) recovery teams.                       cies is information. There is a common behavioral trait
    Analysis of Neotropical data (Collar et al., 1997)      amongacademicsof ignoring literature much older than
 shows that the avian families with significantly high       I0 years, presumably partly reflecting the assumpdon
 numbers of threarcned species suffer from particular        that the data contained in such literature are incorPo-
 rhreats in combination. Thus the parrots     (Psittacidae)  rated into more recent work. Often, in fact, the informa-
 have rhe greatestproportion of threatenedbirds in any       tion has been ignored; sometimes,however, it has been
 tamilr' (2806), closely followed by the curassows and       used but, on proper reconsid€ration,proves tobe faulty.
 guans (Cracidae,26%), and then the tinamous      (Tinami-   There is therefore considerable virtue in seeking out,
 dae. I5"... still almost double the 8% rate of endanger-    assembling,and critically evaluating all iuformation re-
 menr in the \ew World avifauna as a whole). All three       lating to an endangeredspeciesbefore deciding on the
 families arc sensitive to habitat loss; but the parros      most appropriate remedial or m€rely investigative ac-
 also experience intensive trapping for trade purposes,      tion. Despite the need for speed in casesof speciesat
 and the cracrds and tinamous are no less intensively        risk, precipiate intervention can waste hundreds of
 exploited for food. Possessiono[ a distinct economic        thousands of dollars and even prejudice attitudes
 value within a beleaguered habitat t'?e, particularly       against a specieswhen its real needs are finally recog-
 one with some (bio-)geographic restriction, conlers a       nized. For example, captive breeding management for
 strong likelihood oI endangerment.                          the Philippine Eagle (Pithecophaga    jefJeryi), a costly
    However, there are manv endangered birds whose           long-term, but to dat€ unsuccessfulprogram, appears
 rarity has abidingly obscure causes.Among these are         to have come into being in responseto somewhat over-
 the White-winged Duck       (Caitind srutulnla,Southeast cautious estimatesof the bird's population size.
 Asia), Giant lbis (Pseudibis gigantca,lndochina), Hima-         Recent Birdlife Red Data Books have sought to pre-
 Iayan Mountain-quail (Ophrysic superciliosa, lndia),        s€nt detailed synth€seso[ relevant data, extending to
 Bomean Peacock-pheasant        (Polyplectronschleiermach- translations from languag€swith which biologists may
 eri, Bomeo), Negros Fruit-dove (Ptilinopusorc4nus,Ne-       not be familiar, so that a clear picture of a situation
 gros, Philippines), Blue-headedLorlkeet      (Charmosyna    can rapidly be considered and the options objectively
 toropri, Buru, lndonesia), New CaledonianLorikeet      (C.  assessed.However, ther€ are many other examples of
 diqdema) Forest O wlet (Atheneblewitti, India) , Liberian
           ,                                                  the careful construction of evidencein endangeredspe-
 Greenbul (Phl llast rephus leucolepis), Cone-billed Tana-    cies management. One of the most notable is the ex-
 402                                             E ND A NG E R E DB IR D S

 haustive 400-page review of the history, plight, and          mented a major ICDP (integrated conservation and de-
management of the Puerto Rican Amazon (AmaTona                 velopment project) ar Mt. Kilum-ljim to aid local hu-
vitt4td) assembledby members of the team that spenr            man communities around the mountains, and this has
some 20 years piecing together the facts (Snyder et            led to a widespread appreciation oI the biological value
al., 1987).                                                    of the forest withour generaring rhe kind of hostility
    The importance of individual study of endangered           that goes with attempting to create strict exclusion
birds cannot be overstated,although there can be diffi-        zones. The same kind of program operatesar Arabuko-
culties (over logistics, permissions, the generation of        Sokoke Forest in Kenya, home to six endangeredbirds.
statistically uselul data) and dangers(sometimes to the        Other conservation organizations have been using the
student, sometimesto the species)that militate srongly         same fundamental formula-that local people must be
against such work, For larg€r species,radio-tracking is        made part of the solution, not demonrzed as part of
becomingincreasinglyvaluableasa meansofrecovering              the problem.
large quandties of information from a relatively small            Campaigns to promote interest in and support for
investment of effort: speciesas different as Black-faced       species conservation programs are liral elements of
Spoonbill (Platalea minor) and MadagascarSerpent-ea-           those programs. These may rake rhe form o[ extension
gle (E[triorchis astur) have yielded data on movemens          work related to ICDP promotion of sustainableuse oI
and daily behavior pattems rhat are crucial ro their           Iocal resources, or more direct appeals to people to
long-term management.                                          appreciate the unique value of rhe wildlife in their


         B. SiteandHabitat
                         Conservation
                                                                              C. Trade      and
                                                                                     Controls
 The conservation of sites at which endangered birds
 occur, and of the habitat they are known to occupy, is
                                                                             Intemational
                                                                                       Legislation
 the primary management technique for ensudng their             Although trade is not a strong factor in the endanger-
 suwival. The key tool is th€ protected area, which for         ment of birds in general,it is important for a lew groups
 Iarger sitesis usually reflected in law as a national park,    ofspecies, most notably the parrots. The major intema-
 indicating the clear public interest of serdng aside a         tional instrument for the control o[ trade is the Wash-
 major proportion of a country lor noneconomic rea-             ington Convention, universally knou'n as CTTES(Con-
sons. Smaller areas are often designated as nature or          vention on International Trad€ in EndangeredSpecies),
biological reserves,and are frequently consideredmore          which has been in operation since rhe 1970s. Animals
as refuges or scientific laboratories for research pur-        and plants maybe registeredin three \ays: on Appendix
posesthan as sites with a broader public service;public        I, which essentiallyprohibits all movement of the spe-
access can be more difficult than in nadonal parks.            cies in question:on Appendix II. rvhich prohibits all
However, the site of many national parks is important          commercialtradeexceptunder license:        and on Appen-
for consewing viable populations of larger, low-density        dix ttl. which allo*s a particular narion to prohibit
species.Naturally it is appropriate to seek to savethese       ttade across its borders irrespective of a species' sta-
specieswhere they are s)'npatric, thereby maximizing           tus elsewhere.
the efficiency of the expense.Evaluations such as those            Because the immense volume oI traffic in parrots.
                                                                            o[
by Wege and Long (1995), Stou et aL (1996), and                and the problemof identificanonin so diversea family
Stattersfield et al. (1998) provide clear rarionales for       (around 350 species),all but three specieswere placed
the hrgeting of conservation resourcesin such a way            on Appendix ll in 1981. This move had the intention
as to secur€ not just individual species but the key           ifnot the effect of giving protection to the more endan-
representativ€sof biogeographic regions.                       gered parros-naturally their rarity increasedrheir de-
    ln general, endangeredbirds on continents require          sirability among bird-fanciers-which, if listed alone
larger-scalehabitat conservation, whereas those on is-         on the Appendix, could easily have been traded indis-
lands need intensive multi-faceted management (as-             criminately under other names without customs offi-
pectsofwhich are treatedin SectionIII,D). The cardinal         cials necessarilybeing able to idenrify them. Appendix
element in successfulsite conservadonis local support,         II species have quotas set by exporting countries, in
backed of course by national govemment. In its work            theory based on data that show the exploitation to be
since 1983 to conservethe montane foress of westem             sustainable.Where the evidence suggeststhat it is not,
Cameroon (to which 25 speciesof bird are endemic, 9            movement to Appendix I is supposed to bestow im-
oI them threatened), Birdlife International has imple-         munity.
                                               ENDANGERED IRDS
                                                        B                                                          403

    Curiouslv-but as a measureof the power that some           2. Control and/or Restriction of Aliens
trade interests can exert-lisdng on APP€ndix I can                and Natives
actualh stimulate trade (a) while the speciesis still at       Eradication of exotic predators and pests from islands
rhe proposal stagefor upgrading but also (b) following         hasbeen pioneeredin New Zealand,where severalsmall
Iistrng. on the basis o[ its enhanced rarity value. This       offshore islands have been rid of various mammals in
happened to the Hyacinth Macaw (Anodorhynchus          hya-
                                                               order both to preserveresident breeding speciesand to
crnrhinrs). rvhoserarity   in the wild today is primarily a    translocatestricken native sPeci€s  from the main islands
e,.,nsequence a trapping blitz in the 1980s.ln general,
                of                                             (Clout and Craig, in Coulson and Crockford, 1995).
(-ITES trade controls have some effect, and allow for
                                                               This painstakingly systematic restoration of islands-
r cn useful monitoring of changesin trading fashions           mainly involving the elimination of cats, rats, and mus-
ovcr time. However, for truly prized species such as           telids-has been essentialto the survival of birds such
Lcar's Macaw (A. leari) and Spix's Macaw (Cyonopsittd          as the Black Perel (Procellariaparhinsoni) and Kakapo
sptrii), both frorn Brazil, there is little that any control   (Stigops habroptilus), and the expertise generated is
s\stem can do to elirninate smuggling: the financial           now being exported to other islands in the Pacific and
inducements are simply too strong. The same tends to           lndian Oceans.
be true in lndonesia for exquisite songsters like the              Researchers Mauritius recently discovered why
                                                                                 on
Straw-headed     Bulb:ul (Pycnonotus zeylanicus)and Sood-      the native, Critically EndangeredPink PiSeon(Nesoen4s
lLrokers  like the Bali Surling (Leucopsar rothschildi).       mayeri) and Mauritius Fody (Foudia rubra) have man-
    Other important international instruments for en-          ag€d to persist in the face of rat predation. Thesebirds
d.rngeredbirds are the RamsarConvention (ior imPor-            now nest almost exclusively in a grove of exotic Crypto-
r.rnt u'etlands), Bonn Convention (for migratory spe-          meiq japonica, whose bark produces a sticky gum and
cres). and Berne Conv€ndon (for European species).             whose leaves consist of spiny needles,both of which
The Convention on Biological Diversity, already men-           discouragerats lrom getting at nests. Curiously, then,
tioned, ought to be the comerstone of endangeredspe-           in rare casesit appearsthat exotic vegetation can help
cies conservation across the planet. but considerable          rather than hinder native sp€cies in their struggle
e[fort bl nongovernmental organizations is needed to           against exotic predators; in this insbnce the plandng
ensurethe inclusionof global prioritiesin the national         o[ more Crlptomeric is clearly called for.
consenation strategies     that each partl to the conven-          It is not always the casethat exotic predators are the
 tion is obliged to produceand implemenl.                      problem. ln New Zealand, the native weka (Gallirallus
                                                                4ustralis) has proved to be a significant influence in
                                                                depressingthe numbers of Little Spotted Kiwi (Apteryx
              Techniques "Critically
   D. Management       for                                      owenii) marooned on Kapiti lsland, of Cook's Petrel
                    Birds
           Endangered"                                          (Pterodromacookii) on Codfish Island (until removed),
                                                                and of Chatham Oystercatcher (Haematopuschatha'
I. Habitat Restoradon
                                                                mersis) on various Chatham islands. On Bermuda,
Major conservation projects almost invariably involve           White-tailed Tropicbirds (Phaethonlepturus) outcom-
some habitat restoration work. However, for speciesat           pete Cahows (Pterodromacahow) for nests and have to
the brink ofextinction through habitat loss, the empha-         be controlled. As already mentioned, brood-parasitism
sis falls more directly on the rapid replanting of food-        by cowbirds requires intensive local control efforts to
plants and land areas.Lear'sMacaw appearsto be con-             prevent the suppression of breeding successin Kirt-
strained by the availabilitl o[ licuri palms (Syagrus           land's Warbler and Black-cappedVireo.
coronata),many srandsof which show no sign of regen-
eration owing to cattle-grazing: Programs have long
been planned to establish many new Sroveswithin the            3. Captive Breeding
species'range. The Cebu Flowerpecker (Dicaeumquad-             The role of captive breeding in endangeredbirds has
ricolor) survives in an area of heavily degraded forest        long been controversial. The prevailing view among
rhat consists ol a mere 3 km2: efforts are under way to        conservation biologists is that capdye breeding is not
r€forest adjacent areaswithin the next 30 years. There         a major managementtool for endangered     birds, and that
is now an emerging discipline of restoration ecology,          indeed it can positively dishact attention and lesources
and it is likely that a great deal of conservation energy      from serious problems that affect th€ species.The Phil-
in the twenty-first century will be channeledinto recon-       ippine Eagle has already been mentionedi similarly,
figuring habiuts that were ruined during the twentieth.        cranesand parrots have in the past been launched into
  401                                           ENDANGERED IRDS
                                                         B

  ex situ prograrrs in the mistaken belief that maior bene-       for independence in nature. Monitoring of the project
  fits will resulr (bolh species imprint heavily.and par-        is crucial, and it should be documented for circulation
  rots, many of which leam survival techniques through            to other biologists contemplating such effors.
  observation of their parents, are particularly disadvan-           Bird speciesthat have benefited from well-desisned
  tagedfor retum to the wild). Captive breeding hasmany          reintroductionprogramsinclude rhe Neneor Hawaiian
  other drawbacks,notably the particular dangersof dis-          Goose (Branta sandyicensis),    California Condor, pere_
  easetransmissionto wild birds from captive stock (Sny_         grine (Falco pereginus), and Chatham lslands Snipe
 d.er et aL. L996).                                              (Coenocorypha    pusilla). Those rhat have nor incluie
      Nevertheless,captive breeding has achieved several         Cheer Pheasant (Cqtrexs wallichii) in Margalla Hills,
 outstanding successes.    The Northem Bald Ibis (Geron_         Pakistan (fox predation), Shore plover on Mangere ls_
  ticus eremita.) and Califomia Condor (Gyunogps cali_           land. New Zealandlthe birds flew back ro Souih Easr
 fomianus) both flourish in caprivity while efforts to           lsland), and Thick-billed parrots in rhe Unired Stares
 implove environmental conditions in the wild continue.          (the wild-caught birds flew back to Mexico; rhe captive_
 The Lord Howe Rail (Gallirallus qrlvestris) and Guam           bred ones flew nowhereat all).
 Rail (G. owstoni), members of a notoriously vulnerable              Translocation to previously unoccupied siteshas be_
 family (since so many rails reached islands in the past        come a greatly valued technique, if onl) as a temporary
 and proceededro lose the power of [light), probibly            measurewhile efforts are concentratedon habitat resto_
 only persist thank to er sittl regimes. The Socono             ration or predator eradication at the native site. Benefi_
 Dove (Zenaida graysoni) survives only becausea few             ciaries of rhis approach include Niuafoou Megapode
 Californianbird-fanciersrook and bred specimens          at    (Megapodius   pitchardii), Vini lorikeets. Kakapo. Guam
a time before its native island *u, ou"rrun by exotic           Rail lollowing captive breeding. Seychellei Magpie-
predators. ln Ig98 rhe Bali Starling (Leucopsar roth-           robin (Copsychus echellarum) and Sel.chelles
                                                                                    s           ,                WarLler
schildi) was within eight individuals of becoming ex-           (Acrocephalus   seychellsnsis). work done in Dreoara_
                                                                                              The
tinct in lhe wild owing to relentless  poachingtor trade.       tion for the Seychelles  Warbler translocarrons  showed
but zoos throughout the world have bred the species            that target islands had many times the insect abundance
such that many hundredsand perhapsrhousands            sur_    of the host island, Cousin. This was clearly related to
vive for possible reintroduction when poaching has fi-         the absenceof predation pressure on the insecr fauna,
nally been brought under control.                              and-unsurprisingly but still very strikingly-when
     There is also a role for veterinarians in intensive in    birds were releasedonto the target islands they began
situ managementprograms, through their expertise in            breeding almost immediately, and very rapidly ex-
providing appropriate advice on roxicity ofnestbox ma_         panded their numbers. On Cousin the birds had been
rerials, control ofnest parasites.composition   and secure     so packed that they bred only very slowly, with one
provision of supplementary foods, disease screening,           offspring tending ro sray on territory and help at the
and minimization in cross-fosteringand translocation           nest.waiting for a parenl to die { Komdeur, tqq}). This
exerc$es.                                                      observation underscoresthe value of the food resource
                                                               base in managing endangeredbirds, and leads to the
4. Reintroduction    and Translocation
                                                               next point.
 The extirpation of a speciesat a discrete site may have
 been caused by a shorGterm or remediable factor, so           5. Supplementary
                                                                              Feeding
 that restocking with individuals from elsewherecan be         The value of increasing food availability for sDecies
 undertaken. This is usually relevant or worrhwhile only       whose populations need rapid growlh s;ems t; have
 when rhe speciesis globally endangered.bur whatevei           been perceived only relatively recently, perhaps begin_
 the urgency, the endeavor requires careful planning           ning with work on Peregrines(seeTemple, 197g). ihe
 (Black, I991). A seriesof feasibility assessments should      techniquehas been adopredlor endangered        birds on
determine rhe sire's continuing ecological suitability         Mauritius, principally with the Mauritius Kestrel (Falco
 (the original constraining factors must no longer opei-       punctatus),for which extra food clearly enhancedreoro-
ate), the threats it faces,the availability of appropriate     ductive output Qoneser cl., in Coulsonand Crockford,
stock, the socioeconomic implications, and local, na-          1995). New Zealand workers supporting efforrs on
tional, and international awarenessneeds. The birds            Mauritius have found the same with the Kakano: nor_
must be in optimal condition, and if captive-bred thev         mally rhe speciesbreeds only in responsero major
should havebeenrearedin disease-free       condirionsani       masting events,which may occur once every five years,
in such a way as to be behaviorally and genetically fit        but wirh dietary supplements it appears to be capable
                                             E N D A NG E R E DB I R D S                                                 405

o[ bre€ding every year. On Hokkaido, Red-crowned            sidered, but it clearly representsa means of presewing
Cranes (Gms japorlensis)have recovered ftom near-           genetic diversitY.
crtirpation through a combination of better protection
.rnd extensive food provision. Clearly, as a relatively     8. The RoIe of the Concerned Cltizen
short-term measuresupplementary feeding can be cru-         Finally, it is worth stressingthat much of the advocacy
rral in producing an unnaturally rapid reproductive         for endangered birds, and many of the insights into
output, a very desirable effect in critically low popula-   their plight and salvation, comes from national and
tions where the genetic value of every individual needs     international conservation organizations. One of the
to be maximized.                                            most valuable things that any s)'rnpathetic individual
                                                            can do to help endangeredbirds is simply to join or
6. Nest-Site Provision or Enhancement                       support such organizations. Their conservation effec-
Where nest sites are limiting (often the casewith hole-     tiveness depends not only on the financial security de-
nesting species),the provision of nestboxesor the en-       rived from a broad membership base,but also on being
hancement of natural cavities may be appropriate.           recognizedas the representativemouthpieces of a con-
Puerto Rican Amazons ignored the former butbenefited        stituency consisting of millions o{ concerned citizens
from the latter. Mauritius Kestrels greatly benefited
from the creation o[ nesting ledges. The provision of
grilles at entrances has helped Prevent White-tailed
                                                                                        Articles
                                                                         AlsotheFollowing
                                                                       See
Tropicbirds from appropriating Cahow burrows. In the             BIODIVERSITY . CONSERVATION
                                                            BIRDS.          OF              EFFORTS'
Galipagos, a new, more secure colony of Dark-rumped         CONTEMPORARY.ENDANGERED  MAMMALS' ENDANGERED
I'etrels (P. phaeopygia)was establishedby digging nest                           '           MODERN
                                                                   AND AMPHIBIANS EXTINCTIONS,
                                                            REPTILES
burrows and playing calls among them at night.              INSTANCESOF


7. Cross-Fostering and Cross-Breeding
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Many large raptors and most cranes lay two eggs but
normally rear only one young, so biologiss attempting       Black,J. M. (1991).Reinlroduction      and restocking:Guidelines  for
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                                                            Buch€r.E. H. (1992). The causes extinction of the Passenger
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                                                               Pigeon. Currnt O itholos' 9 (D. M. Power,ed ), Pp. l-36
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second eggs by taking them for hatching and captive            PlenumPress,    New York.
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fell to five individuals in 1980 but recovered by the          cil for Bird Presewation,Cambridge,Unit€d Kingdom
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                                                               ed.),Omithological   Morcgraph48, pp.237-260.      Am€rican  Omi-
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                  ,                                             t-owen, C., Tobias, A., Long,A. J., add Crosby, J. (1999).
                                                                        J.            J.                             M
 a single female. After nestboxeswere erected to over-          Threatened  Rirds oJ the PhiliPpines- Bookmark, lnc , Manila
 come an irnmediate shortage, two male nominate male        Coulson, and Crockford, J. (eds.).(1995) Bird consenation:
                                                                      J.,                  N.
                                                                The science  and the action.lbis 137, suPpl. I
 boobooks were introduced to the island; one o[ them        Crosby, J., Stattersfield, J., Collar,N J.. andBibby,C.J. (1996).
                                                                     M.                  A.
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                                                                                 by                    of
+06                                                     E N D A N G E R E DB I R D S

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Kudn, W. E., and Gaston,K. J. (1998). rhr Biolo$/ ol RA4E. Cbap-             vatio4 CoDs€rktion Series7. Btdl-if€ International, Cambddge,
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Moors, P. J. (€d.). (1985). Conse'vdlion lsla/tlt 8ird5. lut€rnational
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                                                                         Stotz,D. F., FitzpaEick, W-, Parker, A., and Moskovi6,D- K.
                                                                                                  J.
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   r0,338-3.+8.                                                              Kingdom.

				
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