October1993] ShortCommunications andCommentaries 933 for granting us the use of the study area,the Campos MARTELLA, M.B. 1985. Observaciones sobre el com- family for their hospitality, and J. Navarro and H. portamientode la cotorraMyiopsitta monachus con Merlini for their help with the fieldwork. We appre- especialenfasis en la comunicacionsonora. Ph.D. ciatedthe helpful commentsof M. Notes, L. Baptista, thesis, C6rdoba Univ., C6rdoba, Argentina. E. Klaas,and E. Morton on the manuscript.This work MARTELLA,g. B., J. L. NAVARRO,AND E. H. BUCHER. was funded by the Consejo Nacional de Investiga- 1987. M6todo para la captufade cotorras(Myiop- clones Cientificas y T•cnicas of Argentina (PID sitta monachus)en sus nidos. Vida Silvestre Neo- 3-908101/85). tropical 1:52-53. NAVARRO,J. L., L. F. MARTIN,AND E. H. BUCHER.1992. LITERATURE CITED The use of remige molting for age-classidenti- fication in Monk Parakeets. Hornero 13:261-262. BROWN,J. L. 1978. Avian communal breeding sys- ROWLEY,I. 1983. Mortality and dispersalof juvenile tem. Annu. Rev. Ecol. Syst. 9:123-244. GalahsCacatua roseicapilla in the western Austra- BROWN,J.L. 1987. Helping and communalbreeding lian wheatbelt. Aust. Wildl. Res. 10:329-342. in : Ecologyand evolution. Princeton Univ. SAUNDERS,D. A. 1982. The breeding behavior and Press, Princeton, New Jersey. biology of the short-billedform of the White- EMLEN,S. T. Observations on a captive colony of tailedBlack Cockatoo Calyptorhynchus funereus. Ibis Quaker Parakeets. Watchbird. In press. 124:422-455. FORSHAW,J. M. 1978. Parrots of the world, 2nd ed. Landsdowne Editions, Melbourne. Received9 April 1992,accepted 22 November1992.

The Auk 110(4):933-936, 1993

Cooperative Breeding by Rufous on Island, Philippines

MARK C. WITMER Sectionof Ecologyand Systematics,Cornell University, Ithaca, New York 14853,USA

Hornbills (Bucerotidae)are unique in their nesting a distinct casquemorphology and bill coloration (il- habits;females seal themselves within the nest cavity, lustrated in Hachisuka 1934). In all subspeciesthe where they lay the clutch and remain with the grow- sexes are similar and all show the same pattern of ing young for most or all of the nesting period. In plumage maturation (McGregor 1909). The juvenal somespecies the male helps with the sealingprocess plumage is distinct with white featherson the head, from outsidethe nestcavity. The nestlingsand female neck, chest,and belly. Subsequently,the pale juvenal are fed by the male through a narrow vertical slit in plumage is replacedby the dark black and chestnut the sealednest opening (Kemp 1979 and references body plumage of adults.The casqueand bill develop therein). Thus far, four speciesof hornbills have been more slowly; many birds have adult plumage color- found to have cooperative breeding systemswith ation but incomplete development of the casqueand helpersat the nest;nonbreeding birds assistthe male bill coloration. Maturation is probably complete in in feeding the nest mates(Stacey and Koenig 1990). about four years (Kemp 1979). Mindanao Rufous Theseare the Bushy-crestedHornbill (Anorrhinusgal- Hornbills develop from a black bill with a low, eritus;Madge 1969), Southern Ground (Bu- humped casque in juvenals to an ivory bill with a corvuscafer [=leadbeateri; see Browning 1992];Kemp prominent, red, anvil-shaped casquein mature adults and Kemp 1980), White-crowned Hornbill (Aceros (see Hachisuka 1934). ! use "immature" to designate comatus;Leighton 1982), and Brown Hornbill (Ptilo- birds that have adult plumage coloration, but which laemustickelli; Poonswad et al. 1983).I report helpers have not yet developed the definitive adult mor- at the nest in another hornbill species,the Rufous phologyand colorationof the bill and casque("adult" Hornbill (Buceroshydrocorax mindanensis) on Minda- refers exclusivelyto thesebirds). nao Island in the Philippines. I observedbreeding activity at two RufousHornbill Each of the three subspeciesof Rufous Hornbill (B. nestson the island of Mindanao, Philippines: one at h. hydrocorax, and ;B. h. semigalea- Mt. Apo National Park near Davao City, Davao del tus, , , Panaon, and ; and B. h. min- Sur Province (7øl'N, 125ø22'E)from 31 July to 25 Au- danensis,Mindanao and [McGregor 1909])has gust 1984;and the other at Lake Sebu, South Cotabato 934 ShortCommunications and Commentaries [Auk, Vol. 110

Province (6ø12'N, 124ø41'E)from 4 to 14 August 1985. I beganobservations on 31 July and watchedthe nest Both sitesare approximately 1,000 m in elevation. The from a ground blind located20 m from the nest tree primary forest vegetation is tropical lowland ever- for a total of 62 h on 9 days (5-8 h per day) from 4- green rain forest (Whitmore 1984) dominated by trees 25 August.On 5 Septembera singlenestling fledged. in the family Dipterocarpaceae(Lewis 1988). I also The nest was a cavity about 14-m high in a 20-m-high recorded Rufous Hornbill group sizes at the Paper rotten tree trunk (102-cm dbh). I could see no seal at Industries Corporation of the Philippines (PICOP) this nest; the female had apparentlybroken out of logging concession (7ø50'N, 126ø14'E) during two the nest by the time I began observations,and the weeks in November and December 1986. The PICOP cavity was either left unsealedor I was unable to site is 600 m in elevation with vegetationof approx- discern remaining sealing material. Thus, I observed imately 20-year-oldselectively logged forest. thesehornbills during the final 45 days(nest discov- The Lake Sebu nest was found on 4 August 1985. ery to fledging)of a presumedfour-month nesting I opportunistically observedhornbill activities at and cycle(see Kemp 1979),during which time the female around the nest daily through 14 August; total ob- was out of the cavity and feeding the nestling. servation time was 12 h. The nest cavity was 30-m Three Rufous Hornbills tended this nest. Both high in the trunk of a huge emergent dipterocarp adults,presumably the matedpair, had blue-grayeyes. (40-m high, 220-cm dbh). This hornbill group was in These birds could be individually identified by dif- the initial phasesof breeding activity and included ferences in tail molt and bill coloration; one had a four adults and one immature (black bill and casque; short central rectrix and a dirty-white bill tip (adult the undevelopedcasque of this hornbill suggeststhat A), while the other had a complete tail with three it was an immediate postjuvenalbird). I was not able new feathersthat were lighter than the rest of the to individually identify the adults. tail and an ivory-white bill tip (adult B). The other An adult hornbill, probably the female, spent 49% hornbill seen at the nest was an immature , rec- of the total observation time (5.88 h) in the nest cham- ognizableby a dark-graybill tip and marooncasque. ber. This bird excavatedthe chamber by chiselling at This bird's casquewas a raised anvil-shaped protu- the cavitywalls and dumping out beak-fullsof wood berance,but it was not as prominent as in the adults; chips. Other group members, including the imma- its eyes were yellow-brown. ture, often perched outside of the cavity entrance, During the nine daysof observationI was able to facing the nest hole, and hammered at the outer rim recognizethe individual feedingthe nestlingfor 66 of the cavity opening. of 72 feeding visits:22 (33%)by adult A; 29 (44%)by The presumedfemale was fed by at leasttwo adults adult B; and 15 (23%)by the immature.The feeders seven times during the two days (10 and 11 August) tendedto arrive and departtogether when delivering that shespent the mosttime (104and 127min) within food to the nest;group feeding visits were followed the cavity. Foodstransferred included fruits (9 of 10 by long periodsof inactivityat the nest.The feeders visible items) and arthropods(1 item). visited the nest singly, in rapid succession,perching On 4 and 8 August I observedcopulation. The first on the bottomlip of the cavity entranceto regurgitate copulationtook placein the nesttree and the second food to the nestling.Individual feedersusually stayed in an adjacenttree. With the pair perchedon the same at the nest cavity for lessthan one minute. The mean branch facing the same direction, the male sidled up number of hornbills tending the nest during a group next to the female and lowered his head forward low visit was 1.8 ñ SD of 0.76 (n = 35). Ratesof visitation under the female's chin, gently shaking his head. to the nestby thesethree birds were notablyconstant. After 1 to 2 s, he hopped laterally over her to land Intervals between feedingsby the group (defined as on the samebranch, where he repeated the behavior a visit by any or all of the feeders)averaged 1.35 ñ from the oppositeside. With eachsuccessive hop the 0.75 h and ranged from 0.25 to 3.00 h (n = 32). Known male appearedcloser to mounting the female. After visit intervals were not significantly different be- five or six of thesehops, the male mountedthe female tween individual birds (ANOVA, Fz35 = 0.04, P = for 1 to 2 s. In the first observation the male then 0.96). Of 83 individual items that I observed being performedthree or four more of the precopulatory transferredto the nestling, 78 were fruits and 5 were hopping displaysand mountedthe femaleagain (with prey (2 cicadasidentified). his tail to the right side of hers) for about 5 s. Just Repeatedsightings of territorial RufousHornbill prior to the 8 August copulation,the female had al- groupsat the two nest sitesand at the PICOP site lopreenedwith anotherof the adult hornbills. enabled me to determine the number of individuals On 4 August three adults moved about the tree in in thesegroups. Family group sizes ranged from three a closegroup, while the immature bird lagged be- to seven birds (œ= 4.3, n = 7). Stott (1947) also ob- hind. On 13 August one of the adults chasedand bill- servedgroups of RufousHornbills in western Min- fenced with the immature bird as the immature tried danao of from three to seven birds. Because hornbills to approachthe other three adults,which were perched in the genusBuceros usually producea single young close together. per nestingattempt and nestno morethan onceper The Mt. Apo nest was discoveredon 21 July 1984. year (Kemp 1979,Poonswad et al. 1986,this study), October1993] ShortCommunications andCommentaries 935 theseterritorial groupsare probably composedof the parative ecologicalwork on thesehornbills might be breeding pair and their young (Stacey and Koenig useful in investigating the causesof cooperative 1990) from previous years' nestings. breeding. The behavior of the Lake Sebu hornbills is com- Acknowledgments.--Ithank the Philippine Bureau parable to descriptionsof early nesting activity for of ForestDevelopment for permissionto conductthis captive(Poulsen 1970) and wild (Poohswadet al. 1986) work and for logisticalsupport. The staffof the Phil- Great Hornbills (Bucerosbicornis), as well as captive ippine Eagle Conservation Program at Mt. Apo Na- (Reilly 1988) and wild (Johns1982) Rhinoceros Horn- tional Park and the Santa Cruz Mission at Lake Sebu bills (B. rhinoceros).The nest site is visited for several generouslyprovided accommodationsduring my vis- months prior to nesting and the female alone exca- its. The Paper Industries Corporation of the Philip- vates the nest from within the nest cavity. The male pines granted me permissionto work on their prop- begins feeding the female when she startsto seal the erty. ! especially thank Susing and Taba Babao for nest, although she still exits to forage on her own. their competent and energetic assistancein the field. Poohswadet al. (1986) also noted copulation during JeanCaleda, Marlo Caleda, Nina Ingle, Richard Lew- this period when the femaleemerged from excavating is, Hector Miranda, Jr., and Bill Wischusenhelped me and plastering the nest. Nest-sealing behavior and in various ways during this work. Mary and Mike materials have yet to be reported for Rufous Horn- Stephenand Lydia Ingle kindly opened their homes bills. The use of living trees for nesting, in addition to me during my staysin Manila and Davao, respec- to the frequent hammeringwithin the nest cavityand tively. This work was partially supportedby a grant on the cavity rim by the Lake Sebuhornbills, suggests from the ChicagoZoological Society. Nina Ingle, Alan that Rufous Hornbills may use tree resin for nest Kemp, Robert Kennedy, Walter Koenig, and Kevin sealing,as observedfor RhinocerosHornbills (Hose McGowan provided helpful reviews of this paper. in Shelford 1899,Johns 1982). Feeding of the nestling by both the male and female breedersat the Mt. Apo LITERATURE CITED nest during the later stagesof nesting is similar to reports for RhinocerosHornbills (Johns1982, Reilly BROWNING,M. R. 1992. Comments on the nomen- 1988) and Great Hornbills (Poohswad et al. 1983). clature and dates of publication of some taxa in Synchronized group feeding visits have also been Bucerotidae. Bull. Br. Ornithol. Club 112:22-27. observed in Brown Hornbills (Poohswad et al. 1983). HACHISUKA,M. 1934. The birds of the Philippine This pattern of nest attendanceby feeding groups Islands, part III. H. F. and G. Witherby, London. may minimize the duration of disturbanceat the nest, JOHNS,A.D. 1982. Observationson nesting behav- reducing the chanceof revealing the nest to preda- iour in the Rhinoceros Hornbill, rhinoc- tors. eros.Malay. Nat. J. 35:173-177. My observationsdocument helpers at the nest in KEMP,g.C. 1979. A review of the hornbills: Biology Mindanao Rufous Hornbills. One breeding group and radiation. Living Bird 17:105-136. consisted of four adults and one immature; the other KEMP,A. C., ^ND M. I. KEMP. 1980. The biology of group consistedof two adults and one immature. Pre- the Southern Ground Hornbill Bucorvus leadbea- sumably, nonbreeding birds were affiliated with a teri (Vigors) (Aves: Bucerotidae).Ann. Transvaal monogamouspair. Helpers assistedbreeding adults Mus. 32:65-100. in nest preparation as well as feeding the nestling. LEIGHTON,M. 1982. Fruit resourcesand patterns of The immature helper at the Mt. Apo nest contributed feeding, spacingand grouping among sympatric a substantialamount of provisioning to the nestling. Bornean hornbills (Bucerotidae). Ph.D. thesis, Cooperativebreeding is likely to be commonfor Univ. California, Davis. Mindanao Rufous Hornbills because territories are LEWIS,R.E. 1988. Mt. Apo and other national parks usually occupiedby three or more birds. The breeding in the Philippines. Oryx 22:100-109. systemsof the other subspeciesof the Rufous Horn- MADGE,S.C. 1969. Notes on the breeding of the bill have yet to be described.Kemp (1979) noted the Bushy-crestedHornbill Anorrhinusgaleritus. Ma- associationbetween unique coloration of juvenal and lay Nat. J. 23:1-6. immature birds compared to adults and cooperative McGRECOR,R.C. 1909. A manual of Philippine birds. breedingsystems in hornbills,suggesting that all sub- Part I. Bureau of Science, Manila. speciesof Rufous Hornbill have helpers at the nest. POONSWAD, P., A. TSUJI, AND C. NGARMPONGSAI. 1983. The other three speciesin this genus have been re- A study of the breeding biology of hornbills ported to breed monogamouslywithout helpers(Rhi- (Bucerotidae)in Thailand. Pages239-265 in Pro- noceros Hornbill, Johns 1982, Leighton 1982; Hel- ceedings of the First Delacour/International meted Hornbill [B. vigil], Leighton 1982; Great Foundation for the Conservation of Birds Sym- Hornbill, Poonswadet al. 1986), although helping posium on BreedingBirds in Captivity. Los An- behavior has been observed in Rhinoceros Hornbills geles,California. (Hose in Shelford 1899,Reilly 1988). Becauseof the POONSWAD,P., A. TSUJI,AND C. NGARMPONGSAI. 1986. diversity of breeding systemswithin this genus,com- A comparativeecological study of four sympatric 936 ShortCommunications andCommentaries [Auk,Vol. 110

hornbills (family Bucerotidae)in Thailand. Pages STACEY, P. B., AND W. D. KOENIG. 1990. Introduction. 2781-2791 in Acta XIX CongressusInternationalis Pagesix-xviii in Cooperativebreeding in birds: Ornithologici (H. Ouellet, Ed.). Ottawa, Ontario, Long-term studiesof ecologyand behaviour (P. 1986. National Museum of Natural Science, Ot- B. Stacey and W. D. Koenig, Eds.). Cambridge tawa. Univ. Press,Cambridge. POULSEN,H. 1970. Nesting behaviour of the Black- STOTT,K. 1947. Notes on the Philippine Brown casquedHornbill Ceratogymnaatrata (Temm.) and Hornbill. Condor 49:35. the Great Hornbill Buceros bicornis. L. Ornis Scand. WHITMORE,T.C. 1984. A vegetation map of Malesia 1:11-15. at scale1:5 million. J. Biogeogr.11:461-471. REILLY,S.E. 1988. Breedingthe RhinocerosHornbill at the Audubon Park and Zoological Garden. Int. Received8 May 1992, accepted28 January1993. Zoo Yearb. 27:263-269. SHELFORD,R. 1899. On some hornbill embryos and nestlings.Ibis 5:538-549.

The Auk 110(4):936-938, 1993

An Early Miocene Passeriformfrom Argentina

JORGEI. NORIEGA• AND LUIS M. CHIAPPE2 •Cdtedrade AnatomfaComparada, Facultad de CienciasNaturales y Museode La Plata, Paseodel Bosques/n, 1900 La Plata, Argentina;and 2Departmentof VertebratePaleontology, American Museum of Natural History, Central Park West at 79th Street, New York, New York 10024, USA

The fossil record of Passeriformes from South The distal condyles are globose and well defined. America had previously been restricted to the Pleis- The dorsalcondyle (Condylus dorsalis) is very convex toceneof Argentina, Brazil and Venezuela (Brodkorb and its proximal area curvesmedially. The distal mar- 1978,Tambussi and Tonni 1986,Cuello 1988,Noriega gin of the ventral condyle (Condylus ventralis) is 1991). In this contribution we report the first passer- remarkablyconvex, and it projectsdistally with re- iform fossil from the Miocene of South America (No- spect to the dorsal condyle. On its medial half, the riega and Chiappe 1991). ventral condyle exhibits a smooth depression,which Recentjoint paleontologicalexpeditions of the State is proximallybounded by the superiormargin of the University of New York (StonyBrook) and the Museo condyle. Argentino de Ciencias Naturales have recovered Proximal to the dorsal condyle there is a subellip- abundant avian remains from the Miocene deposits tical papilla of insertion of the ventral head of the of southern Patagonia (Chiappe 1991). The material M. extensormetacarpi radialis. The dorsal supracon- on which we report comesfrom beds of the middle dylar processis well-developed, hook-shaped,and part of the Pinturas Formation, which outcropsat the proximally projected. The ventral epicondyle (Epi- locality of "Portezuelo Sumich Sur" (Bown and Lar- condylus ventralis) is missing. However, the large riestra 1990), northwestern Santa Cruz Province, Ar- area of break indicates that it must have been exten- gentina. The age of these deposits has been consid- sive and directed distocaudally.In caudal view, the ered to be Early-Middle Miocene by several authors olecranalfossa is superficialand the scapulo-tricipital (Marshall et al. 1983, Bown and Larriestra 1990, groove (Sulcus M. scapulotricipitis)is pronounced. MacFadden 1990). Discussion.--Comparisonsof the specimen were Description.--Thefossil is a nearly complete distal made with members of the Passeriformes and with end of a right humerus (MACN-SC-1411; Museo Ar- thosetaxa considered closely related to Passeriformes, gentino de CienciasNaturales, Secci6n Paleontologla the so-called"perching birds" of Feduccia(1977; i.e. de Vertebrados,Buenos Aires; Fig. lB). In cranialview, Trogoniformes, Coraciiformes and Piciformes). De- the brachial fossa(Fossa M. brachialis) is shallow, not spite its fragmentary nature, the fossil can be un- well delimited, and of subelliptical shape.The ventral questionablyassigned to the Passeriformesbecause supracondylartubercle (Tuberculum supracondylare the ventral epicondyle is prominent and distally di- ventrale) is large and subtriangular. This area is sit- rected. The ventral epicondyle is not projectedme- uatedjust distal and lateral to the brachialfossa. diocranially as in the nonpasseriforms(Fig. 1A), but