Untitled Page 002 [manoa.hawaii.edu]manoa.hawaii.edu/hpicesu/book/1988_chap/24.pdfable I. status of native birds breeding in the Hawaiian Islands.' Endangered or Species Specics Threatened

NATIVE BIRDS

In many areas of the world, birds are!he indicators of ecosystem health and the rallymg pomt forpubltc supporl and consevvatron efforts.

Charles P. Stone

Birds most commol 11y seen in modern-day Hawai'i are alien (or intro- duced) species such as common mynas (Acridotlzeres trisfis), doves (Streptopelia chinemis, Geopelia striata), and house sparrows (Passer domesticus). Unlike native birds, alien species did not arrive in Hawai'i on their own, are not uniaue to the Islands. and are usuallv found in manv other parts of the world.

hative birds do not often cross I;ath, \ w h peq;lc for &era1 reatons. m, humanc in Hau.ai4i rnosrl! liw in 2nd iistt kmcr cd~~at ions, much modi- fied by Polynerian and continental hummc. As :I rule.., nxtive hird5 cannot meet feedine. breedine. and other reauirements in cities and aericultural fields. ~ a n y ~ e c i e s Jna t i vc hird, :& nNlu ~.oniinr.d to rem& areas such as the Northwestern Hawaiian Island5 or hi'lh-elcvatit~l~ iorests, to uhich they have adapted over long periods of evolutionarv time.

A &reason fsi our 1;lcl; o i ~ m t ~ c t ~ ~ " r h n:ltive birds is that many are difficult to see. Unlike much '111nlini:'on rh~. 0 . S . hlninland, for example, a Derson cannot often focus binocularsor spotting scoue out of a car window or ?allow an easy trail very far and hope to see a vxr~ett of species. Forest birds, especially, are often small and green :ml trqucntl! found high in trees in forests that are hard to comforiably visit. One bird book (Prdtt et al. 1987) even goes so far as to list "little green birds" in Hawai'i by island and abun- dance categories to help people sort out some of the species!

But the most important reason that native species are not often seen is that most of them are no loneer nresent. At leait 50% of the native birds 8,nrc found in 1lawai.i are e x h i . About 41%of t h e e species are rare enouch 10 have heen clasified as Endangered or Threatened by the U.S. F I , ~ and Wildlife Sewicc. This horrendous reduction in the world's biolog'cal and cultural heritage is partly the result of reduced forest cover caused hy clclring for arriculture and human settlements at lower elevations. Flouevcr, there are m a 6 other reasons for the loss. Polynesian and continental humans introduced predators such as rats, cats, and mongooses (Raitur exulans, R. rattus, Felis catus, and Herpews auropunctahis). Polynesian humans probably hunted flightless species to low numbers or extinction. Continental humans brought in hoofed mammals (ungulates) such as pigs, cattle, goats, and sheep (Sus scrofa, Bos taurus, Capra liircrfs, Ovis aries), which destroyed, reduced, or degraded native bird habitat. D~seases such as avian malaria and avian pox were accidentally introduced and transmitted by introduced mosquitoes. Alien insect predators reduced numbers of native inseas used

by hirds for food and also reduced insects which pollinated plants used by native hirds. Plants introduced by humans began to compete with and replace natlve ife$ch uf pants. Even introduced species of hirdc, many quite attrac- twe in t leu own r ~ ~ h t , compe!ed with native birds and served as reservoirs for diseascs to whlch natlve blrds had not ada~tcd. A% a result of these limiting factors, working alone or in concert. inanv Hawaiian hirdc todav , arc resiricted to places liast disturbed by humans and their inlrodu~tio&-~ and thev Xre often found in very small numhers cven there.

STATUS OF NATIVE BIRD GROUPS

Limiting factors introduced by humans have reduced many kinds of Hawaiian hlrds to the point of extreme rarity or extinction (Table 1). Groups with eat mobility, such as seabirds (petrels, albatrosses, terns, and so forth r .seem least affected at first dance. but manv of these snecies once ~ ~ . . ~ ~

nested over lar er areas and are n h rcduccd to hreccl:~l:: ,rn'll;,i,&'i';iee- ward islands, okhore itlev, or inacccsdde cliff;. The L.nll:~nrered ilawaiian ~ e t r e l or 'ua'u (Pter&ma ~ h a e o ~ v r i a sandwiclzensir) now brekds onlv in a . . .. h ~ a l l part of its former range, largely on hii.h-zlevstic;r :lope> i n l l a lkka l i Nat~onal Park. Even there, pc l r r l i n nesting n~lonir.i are whjcct to preda- tion bv mongooses and calf (tee S t n w Non-S:~rivc I ar;d \'er~ehrate;. this - volume).

Many species of ibises (Plataleidae), waterfowl, and rails (Rallidae) were formerly native to Hawai'i. The fact that flightless species were largely extinct before the arrival of continental man suggests that these readily available rotein sources were hunted by Polynesians for food. We know that flightless Birds were formerly found on man of the Hawaiian Islands because fossils have been unearthed by researchers ? rom the Smithsonian Institution in Washington, D.C., and by workers from the B.P. Bishop Museum in Honolulu (Olson and James 1982a. 1982b). Surviving waterfowl include the Hawaiian goose or nene (Nesochen sandvicenrir), the Hawaiian duck or koloa maoli (Anas wyvilliana), and the Laysan duck (A. laysanensis); extant (existing) rails include the Hawaiian moorhen or 'alae 'ula (Gallinula cltloropus sandvicensis) and the Hawaiian coot or 'alae ke'oke'o) (Fulica americana alai). All these birds are classified as Federally Endangered. In addition to hunting, the draining and filling of wetlands in Hawai'i, the disturbance of waterbirds by humans, and the introduction of predators such as mongooses and rats certainlv reduced bird numbers in the Dast and are still im~ortant. The ~ n d a n ~ e r e c i Hawaiian stilt or ae'o ( ~ i m a n ? o ~ w ritexicanus knidseni) is affected by similar limiting factors.

Raptorial birds (hawks and owls), like seabirds, are quite mobile, but many vanished prior to the arrival of continental man. Reduction in flightless birds to Drev uDon (in the near-absence of mammals), predation bv Polvnesian humans;and f6restreduction at lower elevations may have contritiuted-to their decline. However, some species may have evo!ved in areas of open habitat, which simply became forested and less hosp~table for these species as the Islands aged. Toda , the Hawaiian hawk or 70 (Buteosolitu'w) is an Endangered species large 7 y because of habitat disturbance, hunting, and a low reproductive potential. Fortunately, it has adapted well to disturbed habitat and alien food sources.

able I. status of native birds breeding in the Hawaiian Islands.'

Endangered or Species Specics Threatened Species with Individuals

Group Knom Left Species >50 <5W** <50#

"Seabirdsm## 22 t 22 2 Hemns 1 1 0 Ibises 2 0 Waterfowl 11 3 3 Hawks 3 I 1 Rails 11 2 2 Stilts 1 1 1 Owls 4 1 0 Crows 3 1 1 Hnneyeatcrs 6 2? 2? Old World Flvcatchers 1 1 0

old world Warblers 1 1 1

Hawaiian Thrushes 6 3 2

Honeycrccpcrs 45 20 9 .. .. . . . . . . . . . .. . . ..-. .. .. .. .. .. . . .. .. ..-.-...............-. Totals 117t 591 24?

* ~ o d i k d from Scott el 01.. 1988.

m~ulation are kmetimes smaller. Po~ulation survival is often much more at risk than . . species survival

X~pDroximate minimum necessary for Iikcly 100-year survival of a population More than one population per species somctimcs cxists (for example, on different islands), so numbers per population arc sometimes smaller. Poprrlatinn survival is often much mare at risk than

#$pcci~s survival. Albatrosses, shewaters, tropic birds, frigatebirds, petrels, tcrns.

T h e dramatic loss of forest birds ( the rest of the roups in Table I), in f bo th kinds a n d total numbers. is thoueht to have resu ted from a c o m ~ l e x of limiting factor\. Aniong these a re 8estruction, fragmentation, and'degra- dat ion of hircl hahitht: ~n t rod t~c t ion oi predators and hoofed acimalc; lorr of invertebrates and ulants needed foifood: and avian diseases. Less mobile species may have hcL'n more w l n e r ~ b l e t " disasters than birds that could move among hahiklt patclie\ ; I I ~ even islands (see Freed et a/. 1987 for a similar ra- tionale on spccinli~m). I)i\prop~>rrionatelv more species of finch-billed honey- creepers, ior examplc. hec:,rnr. e~ t i t i c t in proportion to honevcreepers that fed o n fruits and nectar. Fruit- :d 11e:tar-ieeders msv have had to travel farther in search (Fa wri:ihlr. f ~ d wppl! 11i:in w e d eater3; thus, they may,have been more prcdlspowd o r p r w l ; ~ p t e d tor solonilatlnn of new areas, maintenance

of genetic variation, population interchange, and survival at low population levels.

CONSERVATION OF NATIVE HAWAIIAN BIRDS TODAY

Ecos s t em Approaches d e survival of native birds in Hawai'i depends upon survival of their

habitat. The least costly and surest way to preserve btrds is to keep wetlands and forests from further reduction in quality and quantity. This, and the con- servation of offshore waters also important for some species, usually requires legal protection of large enough areas to support birds, plus some manage- ment to remove or reduce limtting factors. It is preferable to focus on lands (and,waters) that have been little disturbed by humans, which are as large as poss~ble, and which are rich in numbers of native bird species. Areas such as the Hakalau Forest National Wildlife Refuge on the island of Hawai'i, Wai- kamoi Preserve and Haleakala National Park on Maui, the Alaka'i Swamp Natural Area Reserve on Kaua'i, and the Northwest Hawaiian Islands Na- tional Wildlife Refuee are eood examdes. We still have areas in the Islands that could benefit from legzl protecti&, hut we have even more that are legallyprotected but badly in need o i m n a g e m e a to reduce limiting factors for native hirds. Aeain. it cannot he cmohzsized enough 11131 thc securlne - . ' and nlanaglng of entire ecos?stems is hist. hecause nukerous specics beiefit (bird%, plants, invertebrates, and so fonh); hecause prt~cesxs su~,h ac succes- sion. nutrient evclinz. and evolution can remain as natural as Dossible: bec~use specie;depcnd on hab~tat for their life proccses and'evolutih; and hecauhe other approaches (for example, single species emphases) are far more costly in the long run and are less siuccessful.

Single-Species Approaches Unfortunatelv. we are alreadv at the staee in Hawai'i where a number of

s ecies of hirds muct receive costiy individd attention. At one extreme. tRis can he encouraging and arouce puhlic awareness, concern. and imding. The urocram at Hnlcakala National Park to reduce r~redation on hrccdinr 'ua'u'or Hawaiian dark-mrn~ed oetrels is an examoie of an effective sinel& s ecies approach. .4 progra;nc df trapping predatdrs, r,educing garbage land s g elter attractive to rats, cats, and mongo(~ses, and lett~ng the public know about thc prohlem through educatinnarsigns. talks, and iews ieleases has been very effective. Petrel reproductive success increased from 39Ok in 1079 to XU% in 1984 as a result of this active management program.

An example of a less satisfactory, and often misundeYstood, sin le species F - approach is the program to "restore" the nene. State and National ark Service management programs have emphasized the production of birds in captivity for release into the wild. This has been well publicized and supported by the public, and the program is not too expensive, considering the f an that a charismatic and uniaue State Bird is involved. However, desptte a comparatively great amount of'attention paid to a single species in Hawai'i for a long time, nene do not usually produce enough young in the wild, to sustain populations. The released birds gradually grow old and die, and b~rds must be continually released from captive breeding programs to keep "wild popula- tions from declining Predation, nutrition, genetics, aberrant behavior, and disease are all possTble limiting factors. However, the overriding problem,

as with many forest birds, is probably that nene are now confined to a small and substandard portion of their former habitat.

Captive Propagation Raising birds in captivity is also a single-species approach, but hirds are

out of their natural setting or habitat, or ex situ, often with no immediate prospects of successfully reintroducing them into the wild. (The a s i t u approach is discussed in more detail by Giffin, this volume.) When a few of the last individuals of a species are removed from declining wild populations, the situation is usually desperate. The challenge of breeding wild birds in captivity requires development of techniques to allow normal feeding, breed- ing, and other behaviors for each species. Space needs must be determined, diseases readily transmitted by birds in close quarters must be prevented, and human handlers must be careful to keen voune and old hirds from react- - ing shnormdy ron:lrd thcnr. lithe p r # ~ ~ r ; > m ;c:tchr a \r:tgc aherr. h rd \ C:III

he r c l ~ u c d :,nd the rem;unlnr Itahitst i, .uitkhle iur repopoldlion, relr.a.c techoiaues. locations. numbek and genetics of releases must be carefullv con.;id;red. R e l e a d h id , muv hc'monitored to Jetcrniine tltcr ~ n . n ~ ; i t e n t ~ . hrccding bttenipt$ and s.lcce\\, ;ind the bur\ival ,?i\nwig. Oh\io~t\ly. captiw propagation and release programs are costly. long iermrand difficult.

-

Failures are common. The public probably supports these proyams partly because the situation is critical. When a species is in danger o extinction, people become concerned, but often not before. "Preventing extinction" is a more definite, worthwhile, and exciting concept to many than "protecting ecosystems" or reserving biological diversity."

In Hawai'i, such specles as thepo'ouli (discovered in 1973), the large Kaua'i thmsh. the 'o'u. and the Hawaiian crow or 'alala (Melam~roson . . \~ ' ~ I U I ~ Y A ~ I I ~ ~ I . .\fwdt~.sr?% ~ I ~ I . / P ~ ~ ~ I ~ I I . ~ , t ' d r i r ~ m ~ ~ ~ ~ I U I W I . Con,u\ Iru:4 u11,m;~ 1 w1.I pruhahly not be \ a \ d \r i t l i i : ~ . ~ cilpti\e rearing pri.grsrn,. :!nd \omc. , t i t l i r . ~ , will proh;,hl! nut \urccr.J. I t i. Ilkel! too l x e for the u ; ~ ( l l h ~ I~ruc~curr~~), the Jfoloka'i creeper or kakr114 u/r;f, (fJurorc,<,niy:u ]7u1nniw 1, 2nd the o1~11u.o \ . \ lw,it~~rt .> /uw~cnc ;~) of >lolok;t'~ (Scott ~ ~ r u l . , IW8j.

THE FUTURE

hluclr uheful inform:ttion iron1 the Hauai'i I;orc\t IlirJ Sun.ey. conduitcd hy rhc 1,s. t't\h 2nd WilJlii? Servicr, t ~ n rnwr ~ r i rhc ni:,in I h n d ~ irom 1970 to I'JX3, is :~vsil.~hle. D:II:I on i o r ~ ~ t bird di>trihution :md ahund;tnce :it I I I A I point in !me Iiwe ;illtnrctl 11s I.) makc inl'err.ncc\ : I ~ ~ I I I h;,hit.lt prc:c.rc.ltx. m J eiiects of dise;~\c\. ~rtjuldrc! Ji~turh;in:r., srlJ irlritl~de. l I iourhr .~c~ 3bo~1l competition among alien and native birds have been generatid. However, we know very little about limiting factors in different areas over long periods. Dramatic and rapid fluctuations in bird populations are known to occur even for Mainland birds, but in Hawai'i, where populations of many bird species are smaller, less mobile, and more vulnerable to outside disturbances, there have been alarming downward trends in recent years for such species as the 'alala, 'o'u, and even the 'i'iwi (Vestiaria coccinea), in some areas. We simply must understand more about limiting factors and try to reduce or eliminate them while there are still birds. We also need to consider ca~t ive prop3gation at a isr earlier mcl l e dc,rp~.r:ite >ts,ge ior ntmt specicb. he new State facility at the formcr pri,on 21 OlinJa on \Isui is dn ]mport;snt rtcp

in ]hi\ d~rcctim. \Ye c;~n d81 A heucr joh uitli a~ptive propaganon i1u.c hate enough h id , to nnintsin genetic variahilitv and to a\,oid ucr~letinr u ~ l d - nnnuiations seriouslv. - r-.

In all approach& to native bird conservation in Hawai'i, some difficult choices will have to be made. Preserving natural areas rather than devel- nninp. them for enerw nroduction or hotels is but one of thew decision

~ -- - . - --. . . - - . -. - . -- $ink For examplelhhce most remaining habitat for forest birds is above the mosquito/hird malaria zone (4,900 ft or 1,500 m) on the islands of Maui and Hawai'i. do we nut most of our conservation efforts there? Prohahlv the

otKer areas not rich in birds are ecolo~icallvvaluable too because of native ~ ~~ ~

pl:m or in\ertehrate diver$!. and thiv nu! even w r w s, sites for native bird reintroduction i n the iuture.) Clioiies about enipli:~ses plnc~d on land acqui>~tion, rntinsgcment, rc\e;~rcli. mon:tnring of poj~datiuns, and conserva- tion education must u l ~ o he i a c d l'hcre arc not enough fund, and personnsl to dc1 i t d l . \\'hat enlph;14.: dl1 ue giw a p l i \ c p r o p s ~ d o n i n hird cnn\ena- tion programs, as compared with management of iatiiral areas? Which spec~es do we choose to propagate--the ones that are most likely to become extinct in less than 100 years (less than 50 individuals), or those that are now declining but which still have more than one population and considerable genetic variability? Or do we write off all birds with less than a certain minimum viable population (MVP) size?

If Hawai'i's citizens and decision-makers are not informed about choices to be made, the choices will be made by default. Not to decide is to decide. In many areas of the world, birds are the indicators of ecosystem health and the rallying point for public support and conservation efforts. In Hawai'i we need much more information about the birds that remain. But we also des- per+! nced 10 secure snJ m:m;~gc cco\vstelnr whish :ire large '.nough snJ und~,~urhcd enuu~li 1 0 \upport healthv popul:~tinn i1f our n m \ e hird~.

Important References

Hawaiian passerine birds. Trends in Ecology ond Evol&,t 2(7)196-203. Giffin, I.G. [this volume] Captive propagation of birds. Gilpin, M.E., and M.E. Soul&. 1986. Minimum viable populations: processes of spccies

eainction. Pp. 19-34 IN M.E. Soul6 (ed.), Co,rsenvtio,r Biology: nte Scie,rce of Scarcig and Di~crsiQ. Sinauer Associates, Inc., Sundcrland, Massachusetts.

Kear, I., and A.J. Berger. 1980. 77re Hawaiian Goose: An Erperimenl in Conscrvalion. Buteo Books, Vermillian, South Dakota.

Kepter,C.B.,T. Borr, C.B. Cooper,D. Dunatchik, I. Medeiros, J.M. Scott, M.Ueoka, and W. Wong. 1984. Maui-Moiokni Pores1 Bird Recovery Plorr. U.S. Fish and Wildlife Senice, Portland, Oregon.

Mountainspring, S., and J.M. Scott. 1985. Interspecific competition among Hawdiian forest birds. Ecological Monogmphs 55219-239.

Munro, G.C. 1944. Birds of Hawaii. Tongg Publ. Ca., Honolulu. O'Cannor, M. 1986. A Tenclzer's Guide to Endangered Birds of Hawai'i. Hawaii Dept. Land

and Natural Resources, Division of Forestry and Wildlife, Honolulu.

Nalive BirdFIStone 102

Olson, S.L., and H.F. James. 1982a. Pmdror,nu of the Fossil Avifmno of rite Huwaiian Islands. Smithsonian Contributions to Zoology %5. Washington, D.C.

Olson. SL.. and H.F. James. 1982b. Fossil hirds from the Hawaiian Islands: evidence for - -~ . . wholesale extindon by man before western contact. Science 217(4560):633-635.

Pratt, H.D., P.L. Bruner, and D.F. Berrett. 1987. A Field Guide m the Birds of Hawaii ond the Trwical P~cific. Princeton Univ Press. Princeton, New Jersey.

Ralph. CJ. '1982 ids of the forest. ~ a r u m l ~ i s t o ~ y 91(2):41-45. Scott, J.M., C.B. Kcpler, and J.L. Sincock. 1985. Distribution and abundance of Hawai'i's

endemic land birds: conservation and management strategies. Pp. 75-104 IN C.P. Stone and J.M. Scott (eds), Hawai'ik TemstidEcosysIerns: Prese~vation vrtd Ma~tagelnent. Univ. Hawaii Prcss for Univ. Hawaii Cooperative National Park Resources Studics Unit, Honolulu.

Scott. I.M.. C.B. Kcoler. C. van R i m 111. and S.I. Fefer. 19%. Consewation of Hawaii's

Studies in Avian Biology 9. Cooper Ornitholagical Society, Berkeley, California. Scott, J.M.. J.K. Baker. A.J. Baker, E. Kosaka, L. Landgraf, C.J. Ralph, D. Woodside, R.

Bachman. and T. Burr. 1983. Howoii's ~ n r e s t ~ i r d ~ecoven. plan. US. Fish and Wildlife Service, Portland, Oregon.

Shallenberger, R.J. (ed.). 1984. Hawaii's Birds. Hawaii Audubon Society, Honolulu. Simons. T.R. 1985. Biolom and behavior of the endancered Hawaiian dark-rumoed ~ c t r e l ". - . .

~&rdor 87:229-245. Stone, C.P., R.L. Walker, J.M. Scott, and P.C. Banko. 1983. Bawaiian goosc managemcnr and

research--where do we go from here? %!epaio 44(1):11-15. van Riper, C. 111, S.G. van Riper, M.L. Golf, and M. Laird. 1%. The epkooth,logy and

ecological significance of malaria in Hawaiian land birds. Ecolo@cd A4onoppl1s 56(4):327-344.