SYSTEMATICS OF THE SOUTHERN FORMS OF $ELASPHORUS (TROCHILIDAE)

F. GARY STILES Escuelade Biologla,Universidad de CostaRica, CiudadUniversitaria, Costa Rica, Central America

ABSTR•CT.--Basedupon evidence from morphology, behavior, and ecology, I propose that the taxonomyof the southernSelasphorus be set forth as follows: Selasphorusfiammula Salvin: VolcanoHummingbird S. f. fiammulaSalvin, 1864 (Volcfin Iraz6, VolcfinTurrialba, Costa Rica) S. f. torridusSalvin, 1870(Cordillera de Talamanca,Costa Rica-Panama) S. f. simoniCarriker, 1910(Volcgn Po•s, Volc•n Barba,Costa Rica) Selasphorusscintilla Gould, 1850:Scintillant (Cordillerade Tilarfin,Costa Rica south and east to Volc•n Chiriqul, Panama,at lower elevationsthan populationsof the preceding species). Selasphorusardens Salvin, 1870: Glow-throated Hummingbird (Serran•a de Tabasar•, Panama). S. scintilla and S. ardensmay comprisea superspecies.S. "underwoodii"is a hybrid be- tween S. scintillaand S. f. flammula. The breeding distributionsof fiammula,simoni, and torridusare entirely allopatric, but the may occurtogether in the nonbreedingseason. In particular,a pronouncedpost- breeding movementmay carry many torridusinto the breeding areasof fiammulaand even simoni. A possible evolutionary history of these forms is proposed in relation to post- Pleistocene climatic changes, ecological requirements, and probable populations sizes. Received7 June1982, accepted2 December1982.

THE genus ,as presentlydefined resident, although, as we shall see, they en- by mostauthors, includes 6 or 7 speciesof small gage in regular altitudinal movements. (2-31/2g) hummingbirdswith at leastsome ru- Due to the great similarity between some fous in the body plumage and tail; males have speciesand the variability of others,the genus orange,red, or purple gorgets.Geographically, Selasphorushas a long history of taxonomic the genus comprisestwo groups of species:a problems.Even in a relativelywell-studied area northern group, whose three members breed like California, Allen's and Rufous humming- in western North America, with one species birds were not recognized as distinct species extending south in the mountains to Guate- until 1877.The southerngroup presentsan even mala; and a southern group in the mountains more complexpicture, with the statusof tor- of Costa Rica and Panama. ridus and the affinities of simoni in particular Most of the North American populations of still being debated.In this paperI hope to clar- the northern speciesrufus (RufousHumming- ify the taxonomicand geographicrelationships ), sasin (Allen's Hummingbird), and of the various southern forms of Selasphorus, platycercus (Broad-tailed Hummingbird) are based upon a detailed examination of their migratory, wintering mainly in western and plumagesand information on their breeding central Mexico; the population of the latter distribution, annual cycles, and altitudinal species breeding in Mexico and Guatemala, movements. however, is evidently resident.There is thus a gap of severalhundred kilometersbetween the TAXONOMIC HISTORY southernmostpopulation of platycercusand the nearest populations of the southern group, The nomenclatural history of the southern which is not bridged by migration. The south- Selasphorushummingbirds began with the de- ern forms scintilla(), scription of the orange-gorgetedscintilla by simoni ("Cerise-throated Hummingbird"), Gould in 1850 (type locality Volcfin de Chiri- fiammula (), torridus qui). In 1864,the purple-gorgetedflammula was ("Heliotrope-throated Hummingbird"), and describedby Salvin from specimenscollected ardens(Glow-throated Hummingbird) are also by Arc• on VolcfinIrazti, CostaRica. Other Arc• 311 The Auk 100: 311-325. April 1983 312 F. GARYSTILES [Auk, Vol. 100

specimensfrom Volcan Chiriqui provided the suggestedthat it might be only subspecifically basisfor Salvin'sdescription of yet anotherpu- distinct from the latter (but he evidently did tative species, the steely-purple to greenish- not examine their morphologyin detail). He gorgeted torridus,in 1870. In the same paper alsostated that simoniand fiammula were "partly he describedthe red-gorgetedardens from a sympatric"but did not specifywhether or not Salvin and Godman specimentaken at Castillo, this referred to breeding distributions. Wet- Veraguas. Salvin finally bowed out of Selas- more (1968)restored torridus to subspecificsta- phorustaxonomy in 1897 with the description tus, consideringthat the VolcAnChiriqui birds, of a form with a reddish-orangegorget, under- while variable, were clearlydistinct from nom- woodii,from a bird collectedby Underwood on inate fiammula, which he found had not been Volcan Irazd. (For the original descriptions,see collectedby Berlioz on Volcan Chiriqui. Al- the citationsin Ridgway 1911.) though noting specificallya specimenof tor- The first critical analysis of the southern Se- ridus taken by Slud on Volcan Turrialba, how- lasphoruswas made by Carriker (1910),in con- ever, he failed to accountfor the presenceof sultation with the French hummingbird ex- both torridusand fiammulaon the Irazd-Tur- pert, Eugene Simon. Carriker strongly rialba massifand implied thatthe Chiriqui and suggestedthat underwoodiirepresented merely Irazd-Turrialba populations were virtual dis- an extreme variant of scintilla but did not ac- juncts,with birds of thefiammula-torridus com- tually reduce it to synonymy, as he had not plex being rare at best alongthe main Cordille- seen Salvin's type. (Subsequentauthors have ra de Talamanca (despite Slud's statement to considered underwoodiito be a synonym of the contrary). Wetmore did not comment on scintilla.)More important, following a sugges- the possible relationship of simonito ardens. tion by Simon,Carriker recognized that the red- It is worth noting that virtually all the taxo- gorgetedbirds that had been taken on Volcan nomic work on the southernSelasphorus hum- Barba in Costa Rica were different from ardens mingbirds to date has been based on color of Panama in the color of the tail and crissum characters,especially of the males'gorgets and and in bill length; accordingly,he named the central rectrices. Other aspects of plumage Costa Rican birds a new species, simoni. He morphologyhave gone almostentirely unap- was puzzledby the statusof fiammulaand tor- preciated, and measurements have been used ridus, stating that the only differencebetween haphazardly,without attentionto samplesizes. them was in the color of the males' gorgets. In addition, reliable age and sexcriteria, which FollowingSimon, he reducedtorridus to a sub- allow one to comparebirds of the samesex and speciesof S. fiammulabut noted that the two age classof differentforms, have not yet been had been taken together at severallocalities, derivedfrom identifyingbirds not in adult male which, in view of their supposedsubspecific plumage. The distributionsof the variousforms status, he found "rather difficult to explain." have previouslybeen delimited without regard He hypothesized that the torridusin question to distinguishing the breeding distribution were in realityjust worn or fadedfiammulaand from postbreeding altitudinal and local move- that true torriduswas found only in Chiriqui. ments; this, in turn, requiressome knowledge Ridgway (1911) accepted most of Carriker's of what months constitutethe breeding and conclusionsbut raised torridusto speciesrank molting seasons. based upon supposeddifferences in the color of the rectricesof femalefiammulaand torridus. METHODS The statusof torridusand fiammulawas in- vestigatedby Berlioz (1949), who collectedse- This study derives principally from an examina- ries of both forms. He ostensibly found such tion of museumspecimens, supplemented by field- variability in torriduson Volcan Chiriqui that work with all of the formsconcerned except ardens. he consideredit to be a color phase or morph Measurementsof exposedculmen, wing chord, and tail lengthwere takenwith dial calipersof eachspec- of S. fiammula.This conclusionwas endorsed imen, and various morphologicaldetails were noted, by Slud (1964), who noted that torridusand especiallythe form and colorationof all the rectrices, fiammula"evidently coexistin Central Costa which I had found very helpfulfor establishingsex, Rica" but did not provide a detailed analysis. age, and speciescriteria among the northern group He asserted that simoni differed from ardens in of Selasphorus(Stiles 1972). I visited nearly all the colorcharacters only, not in measurements,and high mountainsand majormountain ranges of Costa April 1983] SelasphorusSystematics 313

Rica, where ! was able to observe numbers of simoni, Rectrices.--Patternsand shapesof typical ex- scintilla,fiammula, and torridusin the field. ! mist- amples of the rectrices of the adults of both netted at least some individuals of torridus, scintilla, sexesof all forms are diagrammed in Fig. 1; and simoniand weighed them to the nearest 0.1 or variations in the shape of certain rectricesare 0.05 g with Pesola spring balances.The form most intensively studied has been torridus(cf. Wolf et al. diagrammed in Fig. 2. The two most similar 1976), for which ! have been able to determine breed- forms are undoubtedly fiammula and torridus. ing and molting seasonsand to document some al- The amountof blackor duskyin the outer webs titudinal movements directly. This, in turn, has of the rectricesof adults is slightlymore exten- proved most helpful in evaluating seasonalityand sive on average, in the former, but there is distribution of the other forms, based in part on much overlapin this characterbetween the two plumage data from museum specimens.The south- forms. The amount of black on rectrix 1 in adult ern Selasphorushave dive displays, just as their males varies from essentially none (most tor- northern congenersdo (Banksand Johnson1961, Or- ridus) to a small amount at the tip (some tor- tiz-Crespo 1980), and I have been able to observethe ridus;most fiammula), to virtually all the outer form of these displays,with their associatedsounds, web and much of the inner web being black (a for torridus,fiammula, simoni, and scintilla. few fiammula).The latter condition approaches that in simoni. The rectrices of scintilla differ PLUMAGE CHARACTERISTICS strikingly from thoseof fiammulaand torridus General aspects.--All of the forms of Selas- in pattern (particularly in the amount of ru- phorusare quite similarin generalaspect, which fous) and in shape (particularly in the amount of emargination of the first two rectrices).The has undoubtedly contributed to the problems with their systematics.All are bronzy-green most interestingpoint, however, is the distinct difference between the rectrices of simoni and above and white below, with varying amounts ardens; those of simoni resemble the rectrices of buffy or rufoussuffusion on the sides,flanks, and crissum; males in particular tend to have of fiammulaand torridusexcept for being more extensivelyblackish, while thoseof ardensbear considerablebronze-green spangling on the a rather less close resemblance to the rectrices sides. Adult males have bright iridescentgor- of scintilla. The amount of black on the rectrices gets; the throats of femalesand immatures are of simoniis apparently quite variable; whether varyingly speckledwith dusky and tinged with buff. In all forms the front and sides of the neck this reflectsage or individual variation is im- are immaculatewhite, giving the birds a con- possible to determine from the small series of spicuously "collared" look in the field that is simoni females available to me, only one of not always evident in museum specimens. which is clearly immature (and has rectrices Overall, scintilla is much the most rufescent, intermediatein color,but tending more toward often with only the center of the breast and the dark-tailed extreme). A few adult male belly white; ardens is intermediate between fiammulahave tails virtually identicalto some scintillaand the other forms in this respect, al- simoni,although on the averagethose of simoni thoughits under tail-covertsare usuallywhiter are much blacker,practically lacking green in rectrix 1. The outer rectrices of female simoni than thoseof simoniand, sometimes,fiammula. The form with the whitest underparts is torri- are much more buffy at the tip than are those dus, on the whole; only the crissum is consis- of fiammulaand torridus(with those of fiam- tently tinged buffy. The outer three pairs of mula averagingbuffier than thoseof torridus). rectricesof femalesand immaturesare tipped The outer rectrices of ardens, however, are more or less broadly with white to cinnamon- tipped with still deeper buff to pale rufous, buff. Immatures are recognizable as such for approachingthe condition in scintilla. Thus, severalmonths after fledging by the broad,soft, on the basis of the overall pattern and shape rufousfringes on the dorsalfeathers, especially of the rectrices, the affinities of simoni are clear- on the hindneckand rump. Thesefringes grad- ly with fiammula and torridus, not ardens. In ually wear away, however, and, in any case, turn, ardensseems more nearly related to scin- young birds apparently undergo a complete tilla but is a gooddeal more distinct;it resem- postjuvenalmolt at the same time as, or some- bles simonionly in the large amount of black what later than, the annual molt of the adults in the rectrices of adult males. (see below). Male simoni and ardens differ strikingly in 314 F. GARYSTILES [Auk, Vol. 100

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rl r2 r3 Fig. 2. Variation in the degree of emargination in the tips of the first three retricesof adult males of southern Selasphorus.Abbreviations of forms as in Fig. 1.

green areas of rectrices2, 3, and 4 are usually quite distinct; the black is a deep purplish- black,the greenbright and oftenslightly bluish. In young birds the black is duller, the green less distinct: sometimes there is only a dull Fig. 1. Typical form and coloration of the rec- greengloss on an otherwisedusky-black feath- tricesof adultsof five formsof southernSelasphorus, er, or the entire feather (exceptfor the rufous with variations in the pattern of rectrix 1. Abbrevia- areas)may be a dull dusky green. The differ- tions for forms: sc = scintilla, a = ardens; si = si- ence is most evident on the second rectrix. rnoni;f = fiamrnula;t = torridus. Youngmales usually have a gooddeal less white or buffy on the tip of the third rectrix than females have; young females have the least emargination on the first two rectrices. The rectrix shape (Fig. 2). The degree of emargi- same general differencesseem to hold for si- nation in rectrices 1-3 of sirnoni resembles or rnoni, although more data are required from exceedsthat found in rectricesof fiamrnulaand definite immatures to confirm this. In scintilla, torridus,which resembleeach other closelyin sex and age determination is easier. Young this respect. •I•e rectricesof scintilla are rather malesdiffer from femalesof all agesin lacking more acuminate but less emarginate, whereas rufous at the tip of the secondrectrix and in those of ardens are the bluntest and least emar- having far lessgreen in the tail in general(with ginate of all. the greenmore towardsthe edgesor tips of the In fiamrnulaand torridus,immatures can often feathers,never extendingto the bases).Young (but perhapsnot invariably) be distinguished femaleshave more green in the first two rec- from adults by the duller, less patterned rec- trices than adults have and the pattern is much trices (Fig. 3). In adult females,the black and less clean-cut. The one known young male of April 1983] SelasphorusSystematics 315 ardens differs from the adult female most strik- ingly in the patternof the secondrectrix, which has much more green and only a very narrow pale tip; the immaturefemale of ardensis un- knowTl. Other plumagefeatures.--The form of the re- migesis oftenmodified in adultmale hum- mingbirds(but only rarely in females)in re- lation to sound production during flight (Henshaw, in Bent 1940; Ortiz-Crespo, un- publ. data). In particular, the outermostpri- mary is often modified at the tip. Such modi- fications occur in all three northern speciesof Selasphorus,withthe modifications beingmost similar in the two most closelyrelated species, sasinand rufus(Ridgway 1911).The southern Selasphorusbreak into two distinct groups on the basis of modificationsof the tenth primary in adult males: in ardens and scintilla this feath- er is greatly attenuatedat the tip, whereas in simoni,fiammula, and torridusthere is no evi- dent modification whatsoever (Fig. 4). The wingsof flying adult male scintilla produce a thin, rather -like trilling; unfortunately, nothing is known about the flight of ardens. No suchtrill is producedby malesof the other three forms, although all are capable of pro- ducing a sharp deep buzz in certain situations. This buzz seemsmuch like that produced by displayingLittle Hermits (Phaethornislongue- mareus) and other small hummingbirds with apparentlyGorget shapeunmodifiedis another primaries.character sometimes used in classificationof adult male humming- birds, but I can find no clear-cutpattern among the forms treated here (Fig. 4). The various forms differ in the extent to which the gorget extends laterally into "wings." The most "winged" gorgetsare thoseof scintillaand tor- ridus,with that of fiammula slightly to moder- ately less so. The gorget of ardens is not "winged" but square-cut,while that of simoni is typicallyslightly but distinctly"winged" (Fig. 4).

MEASUREMENTS Fig. 3. Representativepatterns of rectricesof im- Measurementsof bill, wing, and tail (Table matures of four forms of southern Selasphorus.Ab- 1) tend to emphasize the uniformity of the breviations for forms as in Fig. 1. Although the amount of black in the rectrices increases on the av- southern Selasphorusas a groap, rather than eragefrom torridusto fiammulato simoni,the degree showing any striking deviation from the over- of variation is such that many immatures cannot be all pattern. In virtually all cases,adult males assignedsafely to form on this basis. have significantly shorter bills and wings and longer tails than do adult females(the soleex- 316 F. GAa¾ STILES [Auk, Vol. 100

,.• ce) or)

< April 1983] SelasphorusSystematics 317

TABLE2. Resultsof statisticalcomparisons (Student's t) between measurementsof different sexes,ages, and formsof southernSelasphorus hummingbirds. •'•'

A. Intraspecificcomparisons between different sex and age groups Adult c• c• vs. Adult c• c• vs. Immature c• c• vs. Adult 2 2 vs. adult 2 2 immature c• c• immature 9 2 immature 2 9

Form EC WC TL WC TL EC WC TL WC TL

scintilla 11.66'** 20.20*** 5.26*** 8.87*** 4.95*** 7.22*** 4.70*** 0.85 ø 1.18 ø 1.48 ø fiammula 9.95*** 9.86*** 4.04*** 1.71ø 4.00*** 5.24*** 4.44*** 0.55ø 0.04ø 0.18ø torridus 10.44'** 10.43'** 5.98*** 1.13 ø 2.33* 3.99** 1.85 ø 1.91 ø 0.68 ø 0.85 ø simoni 6.86*** 6.49*** 3.25** 1.83 ø -- -- • .... ardens 5.42*** 1.24 ø 9.45*** ......

B. Comparisonsof simoniwith other forms (adults) Males Females

Form EC WC TL EC WC TL fiammula 10.71'** 4.07*** 0.28ø 6.72*** 4.06*** 0.65ø torridus 10.40'** 4.79*** 2.12' 8.97*** 4.26*** 0.60 ø ardens 4.48*** 0.99 ø 3.63** 5.01'** 2.17' 4.10'*

a Measurementsare: EC = exposedculmen; WC = wing chord; TL = tail length. b Levelsof significanceare: ø = P :> 0.05; * = P <: 0.05; ** = P <: 0.01; *** = P <: 0.001.

ceptionis ardens,where a very smallsample of For only two forms, torridusand scintilla, is femalesaverages barely larger than males in there a reasonablesample of weights (Table 1). wing length). Thesesexual differences are gen- As would be expected from measurements, erally less pronouncedin juveniles than in males are lighter than females, and scintillais adults. In particular,young maleshave slightly much lighter than torridus.Indeed, by weight (simoni,fiammula, torridus) to moderately(scin- scintillais the smallesthummingbird in Costa tilla) longer wings than do adults;the greater Rica and, at most, is only slightlyheavier than difference in scintilla (the only such compari- Mellisugahelenae, reputedly the world's small- sonto be statisticallysignificant) doubtless re- est bird. The small sample of weights of simoni flectsthe modified tenth primary of adult males suggestthat this form is about as heavy as (if (Table 2). Bills of juveniles often averageshort- anything, slightly heavier than) torridus. er than do those of adults of the same sex, due to the presencein samplesof juveniles of very ANNUAL CYCLES young birds with incompletelygrown bills (Table 1). Plumage data for all forms, gathered from As expectedfrom plumagecoloration, the two museum specimensand mist-netted birds, are most similar forms in all measurements are summarized in Fig. 5. In all forms the main fiammulaand torridus.Simoni averages signifi- molting seasonof adults is the late dry season cantlyshorter than thesein bill andwing length to early wet season,roughly March to July; tor- but not in tail length; indeed, its bill is the ridus appearsto molt slightly earlier, and scin- shortestof any of the forms consideredhere. tilla slightly later, than other forms. Given that The smallestform in wing and tail length (and the usual pattern in birds in general (Payne only slightlylarger than simoniin bill length) 1973) and hummingbirds in particular (e.g. is scintilla. The most deviant form, in terms of Stiles1980) is for breedingto precedemolt with measurements, is ardens;it shows extreme sex- little overlap, one would expect the breeding ual dimorphism in bill and tail length, almost seasonsof all formsto be endingabout March. none in wing length. Compared with simoni, The beginning of the breeding seasonis more the bill is significantlylonger, sex for sex, in difficult to gauge, becauseplumage condition ardens; males have significantly longer, fe- per se giveslittle information on this point. In malessignificantly shorter, tails than do males the best-studied form in the field, torridus, and females of simoni (Table 2). malesmay occupybreeding territoriesand be- 318 F. GARY STILES [Auk, Vol. 100

s c cr s i t: Fig. 4. Gorgetshape (typical form with variantsshown in dottedlines) and form of the tips of the three outermostprimary feathers(primary 10 uppermost)in adult malesof southernSelasphorus. Abbreviations as in Fig. 1.

gin dive displays as early as late July or Au- largelyor entirelydisappears from mid- to late gust;the earliestnest I have found, however, March throughJune or July (Wolf et al. 1976). was under constructionin earlySeptember, and Althoughwe oncethought that this constituted the earliestfledglings I have seenwere in early mostlya shift to foresthabitats, I am now con- November (cf. Wolf et al. 1976). The same seems vinced that a considerablealtitudinal compo- to be true of fiammula:I found males display- nent is involved as well. I have seen definite ing and a just-completednest on Volc•n Iraz• adult male torridus as low as 1,350 m (Paraiso) in late August1968. The availabledata on other and 1,600 m (Estrellade Cartago)in May and forms suggestsa similar picture: an October June but not at other times of year; this form nest was reported for scintilla by Wetmore has never been recordedbreeding below 2,000 (1968), and females of severalforms with fairly m (and rarely below 2,500 m, in my experi- fresh remiges and very worn belly plumage ence). Data for other forms are scarce,but J. E. have been collected in November-December. S•nchez reported seeing a male fiammulajust Fresh-plumagedjuveniles of fiammula, torri- east of Cartago (el. 1,350 m) in June 1973. By dus, and scintilla have been taken as early as late August and early September,I have seen November. The peak of the nesting seasonfor malefiammula on territory and giving dive dis- torridusand fiammulaseems to be December- plays at elevations from 1,800 m to over 3,200 January (pers. obs.; R. G. Campos pers. m on both Volc•n Irazti and Volc•n Turrialba. comm.). Unfortunately,practically none of the long se- This patternis somewhatcomplicated by the ries offiammulataken on thesevolcanos by Un- presenceof occasionalmolting birds in Au- derwood and others has the elevation marked gust-October,rarely even aslate as December. on the specimenlabel! Available data for scin- Wherever both the incoming and outgoing tilla suggestthat it breedsmainly below 2,000 plumagescan be clearlyidentified, however, m in Costa Rica (see below). In August 1966, thesebirds are seento be undergoingthe first however, I collecteda young male of this form prebasic (postjuvenal)molt. In specieswith in an overgrown pasture at about 2,450 m on protractedbreeding seasonsit is not unusual Volc•n Po•s, suggesting that postbreeding for somejuveniles, presumably those fledged wanderingmay sometimesbe uphill in scintil- late in the season, to molt much later than do la. adults (cf. Williamson 1956 and Stiles 1973 for Unfortunately, little can be concludedre- Calypteanna). garding the annual cycle of ardens.The type One other aspectof the annualcycle deserves seriesin the British Museum containsthe only mention: the possibilityof local cr altitudinal molting specimen I have seen, but unfortu- migrations.On the Cerrode la Muerte,torridus nately only the year of collectionappears on April 1983] SelasphorusSystematics 319

o

o

.... .scintilla -- aimoni...... -o trlammula ß ard:ns torridus

Fig. 5. Annual cycleof plumageand molt in five formsof southernSelasphorus. Upper graph:variation in mean plumagestage (on a semiquantitativescale of from 0 = very worn to 3 = fresh)for nonmolting adults.Molting periodsindicated by horizontalbars; narrow bars = 50% or fewerof individualsin sample undergoingprimary molt; thick bar: over 50% of individuals molting. Note the longermolting period and lower synchronyin molt of immatures(first prebasicmolt). Lowergraph: progress of primarymolt in adults (lines connectingmonthly means) and immatures (unconnectedpoints). Primary molt stage= number of full-grown new primaries. Samplesizes for molt and plumagestages not indicated, but usually small, five or fewer individualsper speciesper month. the label! All dated specimensI have examined and sightings,are presentedschematically in are moderatelyworn birds taken in the month Fig. 6. The following overallpattern seemsto of March. These birds are about as worn as emerge:simoni, fiammula, and torridusare high- specimensof scintillataken in March in Chi- elevationforms, found mostly near the tops of riqui (Fig. 5), suggestingthat the annual cycles the highermountains of the CordilleraCentral of ardensand scintillamay be similar. and the Cordillera de Talamanca; scintilla is a middle-elevation form, found mostly lower DISTRIBUTION down on all of these mountains (and extending north to the Cordillera de Tilarfin); and ardens The breeding distributions of all forms of is restricted to the Serrania de Tabasarfi, a much southern Selasphorus,based upon specimens lower range eastof the Talamancasin western 320 F. GARY STILES [Auk, Vol. 100

-- •000 • • 4000'm--

i

IOO •. Fig. 6. •chematicdiagram of majormountain areas of southernCentral America, with known breeding distributionsof Selasphorushummingbirds (as indicatedby sightingsor specimensin the breeding season, as well as ac•al nesting repo•s). All localitiesknown for ardensare plotted, althoughmost recordsare for the month of March, which may be after the breeding seasonfor this fo• (seetext). Numbered localities are: 1 = Vo]c•n Po•s; 2 = Vo]c•n Barba; 3 = Volc•n Iraz•; 4 = Volc•n Tu•alba; 5 = Ce•o de ]a Mue•e; 6 = Ce•o Chirp6; 7 = Ce•o D•rika; 8 = •abanasde D•rika; 9 = CerroKamuk; 10 = Vo]c•n de Chiriqui; 11 = Ce•o Santiago; 12 = Cerro Flores; 13 = Cerro Tute. Symbolsfor fo•s as in Fig. 5.

Panama, and occupiesabout the same eleva- eitherfiammula or torridus.Thus, it remainsan tions as does scintilla to the north and west. unprovenassumption that movementsof fe- Published information (e.g. Slud 1964) and males (or iramatures)parallel those of their re- museumspecimens suggest considerable over- spectiveadult males, althoughat this stage I lap betweenfiammula and torridus,due mainly certainlysee no reasonto suspectotherwise. to the occurrence of the latter on Volcan Iraz•i The breedingdistribution of scintillais cen- and VolcanTurrialba. Inspectionof the torridus tered lower than that of the aforementioned records concerned, however, reveals that all of forms.Some overlap may occurlocally at around them fall betweenMarch and Julyand that most 2,000 m (cf. Wetmore 1968). Both scintilla and of the specimensare molting birds. This is pre- ardens have been taken on Cerro Flores, in the cisely the time that torridusmoves downhill westernpart of the Serraniade Tabasarain ex- from its known breeding haunts on the Cor- treme easternChiriqui. These birds were col- dillera de Talamanca;evidently this postbreed- lected in March, however; the scintilla in ques- ing movementmay carry the birds not only tion were a worn male beginning body molt downhill but up the other side, onto the Cor- and a juvenilefemale, both of whichcould have dillera Central. Particularlyinteresting in this arrived via postbreedingdispersal. There is connectionare two green-gorgetedtorridus from thus no evidence that scintilla breeds east of Volcan Poas, in the range of simoni.Both are VolcanChiriquL It thereforeappears that the in heavy molt and were collectedin May. A breedingranges of ardensand scintillaare also malefiammula taken on VolcanBarba in April separate,on presentevidence (but seebelow). suggeststhat postbreedingmovements to oth- er ranges occur in that form also. Thus, the DWE DISPLAYS available data indicate that the breeding ranges of torridus,fiammula, and simoniare entirely I presentdescriptions of the dive displaysof separatebut that postbreedingmovements re- the four forms of Selasphorusresident in Costa suit in somemixing, most notably from an in- Rica; I have never seen ardensin the field, and flux of torridus onto the Cordillera Central. I publishedinformation on its behaviordoes not emphasizethat this pictureis derivedfrom the exist.The followingare excerptsfrom my field studyof adult males;I cannotdistinguish most notes: adult femalesof fiammulafrom those of torri- (a) torridus(8-11 February 1972, Cerro de la dus, and some females of simoni are virtually Muerte): "Displays are of the pendulum type. indistinguishablefrom the smallerexamples of U-shaped--bird makes next dive from same April 1983] SelasphorusSystematics 321

side as preceding one ends up; dives at a steep The dive displayof scintillathus differsstrik- angle from a height of 50-75 feet, not quite ingly from those of the precedingthree forms vertical; high, thin whistles are heard on both in three major respects:the longer sputter at dive and upswing--the former louder and the bottom (twice as many syllables)the arc scratchy, the latter softer and clearer, some- sound provided by the wing-trill, and the times lacking?At the bottom, four rapid-fire presenceof a zigzag flight during the climbing dry clicks: fut-fut-fut-fut, reminiscent of bot- phase. tom sound of Selasphorusplatycercus." (b) fiammula (13 January 1979, el. 2,900 m, THE CASE OF SELASPHORUS "UNDERWOODII" VolchnIrazti): "a U- or J-shapeddive (U-shaped if more than one dive per bout); bird dives The long-standing treatment of S. "under- from height of 15-20 m, near vertical at start, woodii"as a synonymof scintillaoriginated with describingarc of a circle at bottom. High, thin Carriker (1910) and was emphaticallyendorsed whistlesgiven both comingand going[sic], that in a footnoteby W. J. Holland, who edited Car- of the dive louder than that of the upswing; at riker's manuscript. Carriker basedhis proposal bottom four dry "chuts" in a quick sputter." on the individual variation in his series of scin- (c) simoni(16 March 1972,Volcgm Po•ts): "only tilla as compared with Salvin's description of single dives seen; birds evidently near end of underwoodii.Carriker statedclearly that he did breedingseason, many immaturesabout; some not actually examine Salvin's type specimen, adults starting to molt. Dive is J-shaped,nearly and evidently subsequent authors who fol- verticalfrom a height of 50-60 feet. A high thin lowed his suggestion did not do so either. I whistled note as bird comes down, slightly recently was able to examine the type of un- higher and thinner than that of fiammula (= derwoodii in the British Museum and find that torridus);at the bottom 3-4 sharp dry "fut's" not only is it definitely not scintilla,but it dif- in a sharp sputter. Overall very similar to dive fers from all other forms of Selasphorusin sev- of fiammula." eral respects!The specimen is an adult male Clearly the dive displaysof thesethree forms collectedby C. F. Underwood on 20 February are virtually identical, far more similar than 1896 at an unspecified elevation on Volcfin Ir- those of any two North American speciesof az•; it is in fairly worn plumage.The gorgetis Selasphorus,even the very closelyrelated S. ru- a curiouspale purplish-redwith a stronggold- fus and sasin(Ortiz-Crespo and Stiles unpubl. en-orange sheen. The underparts have much data). The minor differences noted in the dive less rufous than those of scintilla,more closely of simoni most likely reflect the late date (the approximatingthose of fiammulain the amount end of the breeding season)and the fact that of greenrecking and buffy feather-edgings.The only single dives were seen;the lack of a pro- rectricesdiffer from those of scintillanot only nounced upswing following the dive (i.e. for a in the greateramount of black (cited in Salvin's seconddive) probably accountedfor the lack description),but in having considerablegreen of a softer"upswing whistle" in the observed on the first rectrix and in the tips of the first dives. two rectrices being more emarginate (ap- (d) scintilla (7 November 1982, Las C6ncavas, proachingthe condition in fiammula);the fifth Prov. Cartago,el. 1,320 m): "a U-shaped dive, rectrix is identical in pattern to that illustrated ca. 15 m in height, the dive less steep and the (Fig. 1) for simoni. The outermost primary is arc broader than in fiammulaet al. The wing- less attenuated at the tip than that of scintilla. trill is heard during the dive itself, and at the The measurements (exposed culmen 11.2 mm, bottom the bird makes a dry, rippling sputter wing 35.4, tail 24.9) equal or exceed the max- of 7-8 dry clicksor snaps,less sharp and loud imum values for scintilla (cf. Table 1). In short, than the corresponding sounds of fiammula. I concludethat S. "underwoodii"cannot be any- Halfway up the climb to begin the next dive, thing else but a hybrid between scintillaand the male's trajectorybecomes violently undu- some other form, almost certainlyfiammula in lating or zigzag, as he weaves abruptly from view of the locality,date, and gorgetcolor. This side to side--the amplitude of the zigs ca. 50 is the first hybrid reported for the southern cm. During this zigzagging flight the wing-trill group of Selasphorus(and, indeed, the first in~ sounds broken rather than continuous as dur- tragenerichybrid for the genus;cf. Banksand ing the rest of the dive." Johnson 1961). 322 F. GARYSX•LES [Auk, Vol. 100

DISCUSSION but can also be producednaturally by land- slidesor volcanicactivity or artificiallyby hu- The major taxonomic conclusionsof this man activity in forested areas. All three sub- study are the following: species of S. fiammula are associated with (a) The five forms consideredhere break into flowers like microphylla,Tropaeolum two distinctgroups: fiammula, torridus, and si- spp., and Salviaspp. during breedingand also moni; and scintilla and ardens. Simoni and ar- visit a variety of largelyinsect-pollinated flow- densare not doselyrelated; the fact that males ers in families like Ericaceae, Rosaceae, and havesimilarly-colored gorgets and similarwing Melastomataceae(cf. Wolf et al., 1976). If one lengthsis bestascribed to convergence(or co- views simoni,fiammula, and torridusas mem- incidence). bers of a single complex,certain trends in the (b) Similarity of plumageand displaysin- complexbecome evident over its entire range. dicatesthat simoni,fiammula, and torridusare There is a trend toward smaller size from south best consideredsubspecies of a singlespecies, to north, paralleledby trends toward increas- S. fiammulaSalvin. The allopatricbreeding dis- ing buffiness in the ventral plumage and the tributions of these forms eliminate previous tips of the rectricesin females and toward in- doubts about consideringthem as subspecies creasingly brighter, redder, and less (especiallyfiammula and torridus);the similar- "winged"gorgetsin the males.In all of these ity in displayssuggests that the threeare prob- features the difference between simoni and ably not reproductivelyisolated (see below). fiammulais greaterthan that betweenfiammula (c) While closelyrelated, scintilla and ardens and torridus.I think that this pattern may have differ from each other considerablymore than a simple historical explanation,related to the do any two membersof the fiammulacomplex. amount of breeding habitat available to each Especiallyconsidering the lack of information of the forms and their consequentpopulation on displays of ardens,I think it wisest to con- sizes. tinue to recognizethem as distinctspecies. To- At the presenttime, and probably for much gether, scintillaand ardensmight comprise a of the recentpast, the amountof goodbreeding superspecies. habitat available to simoni has been far smaller (d) S. "underwoodii"is a hybrid between S. than that availableto fiammula;in turn, fiam- f. fiammulaand S. scintilla. mula has had far less available habitat than tor- The most radical changefrom previous clas- ridus. The two peaks that comprisemost or all sifications is the association of simoni with the of the breeding range of simoni,Volcan Poas fiammulagroup and ardenswith scintilla.That and Volcan Barba, are much lower (2,704 and this arrangementhas not been suggestedhere- 2,906m, respectively)than the two peaksof the tofore is probably due to the preoccupationof Irazti-Turrialba massif (3,452 and 3,328 m, re- previous authors with the color of the males' spectively) that form the breeding range of gorgetsto the exclusionof other characters: fiammula.The areaabove timberline on the lat- thus, from its original descriptionto the pres- ter massif is quite extensive, and eruptions of ent time, simonihad always been comparedto Volcan Irazti have alsohelped to producelarge the similarly red-gorgeted ardens, never to areas of stunted scrub that are slow to return fiammulaand torridus.Color of the rectriceshas to forest in the cold temperaturesat 3,000 m been cited cursorily,and detailsof their shape and above. By contrast,neither Poasnor Barba and patternlargely ignored. From previous ex- extends appreciably above timberline, al- periencewith the northernmembers of Selas- thoughboth havewind-stunted elfin forestnear phorus(Stiles 1972), however, I regardthe form their respectivepeaks, and eruptionsof Volcan and patterns of the rectrices as an extremely Pofishave alsoproduced areas of stuntedscrub. useful guide to affinitiesin this group. The Cordillera de Talamanca, on the other hand, The taxonomicarrangement proposed here has extensiveareas of pararnoon at least a doz- makes good sense ecologicallyand zoogeo- en peaks that rise well above 3,300 m; much of graphicallyas well. The threemembers of the the spine of this range is above3,000 m and is fiammulacomplex are all high-elevationhum- coveredwith pararnoor subpfiramovegetation mingbirdsof pararnoor pararno-likehabitats: in which torridus is common. Thus, based on clearings,forest edge, scrub,etc. Suchhabitats available habitat, I believe that the total pop- occurat very high altitudesabove timberline ulation of simoniis, and probably has always April 1983] SelasphorusSystematics 323

been, much smaller than that of fiammula, ble directionof gene flow, basedupon popu- whosepopulation is in turn much smallerthan lation sizes, would be torridusto fiammulato that of torridus. This is reflected in the far simoni;certainly this agreeswith availabledata smallernumber of specimensof simonithat have on postbreedingmigrations. The variability in been collectedas comparedto fiammula,espe- tail patternof femalesimoni, and the closeap- cially consideringthat all of the volcanoscon- proachof somemales of simoniand fiammula cemed are dose to major cities on the Meseta in this character,might indicate gene flow. Central. The relativelysmall number of torridus Also, I have seenseveral fiammula males with in most museums reflects the relative inacces- a few duller, torridus-likefeathers at the edge sibility (until recently) of most peaks of the of an otherwisetypical fiammulagorget. By Cordillerade Talamancaand is not due to any contrast,I have seenno approachto fiammula scarcity of the birds themselves.While it is color in the gorgetsof torridusmales on the probablethat deforestationof the Pacificslopes Cerro de la Muerte, the northernmostmajor of the majorvolcanoes of the CordilleraCentral massif of the Cordillera de Talamanca; the de- in the last two centuriesor so has augmented gree of variability, from dull greento greyish- the amount of good Selasphorushabitat, and purple,seems similar along the lengthof this doubtlessSelasphorus populations as well, this range (I certainly have seen nothing to sub- effect has probably been most pronouncedon stantiateBerlioz' claim of fiammula-likegorgets Volc•n Iraz•i and has therefore not greatly af- amongthe torridusof VolcgnChiriqui). It would fected the relative sizes of the populationsof be interestingto know whetheror not and how the three forms. the relativeproportions of greenish-and pur- During the coolertemperatures of the Pleis- plish-throatedmales vary along the Talaman- itocene,it is probablethat p•ramo-like vege- cas. The very existenceof this variability is in- tation extended as low as 1,500-2,000 m in terestingregardless of its cause;it suggeststhat southern Central America (cf. Wolf 1976 and gorgetcolor per se may not be terribly crucial includedreferences). It in thus quite likely that in mate choiceby femalesof this group. This the ancestralproto-fiammula population was in turn would arguefor the possibilitythat gene distributed continuouslyfrom northern Costa flow couldstill occurbetween simoni, fiammula, Rica southat leastto Volc•n Chiriqui. With the and torridus--especiallyin view of the similar- warming trend of the last several thousand ity of their dive displays.I shouldnote at this years, the p•ramo habitat and its associated stagethat dive displaysmay not be the most hummingbirds, specificallySelasphorus, have critical isolating mechanismsin these hum- been restrictedto progressivelyhigher eleva- mingbirds (Stiles1982). The close-rangedis- tions. The concomitant fragmentation of the plays that immediatelyprecede mating, how- breedinghabitat in turn causedfragmentation ever, have not yet been describedfor southem of the ancestralproto-fiammula population; the Selasphorus,and in North American hum- fate of the different segmentsof this popula- mingbirdsas a group, divergencein thesedis- tion becamelinked to the ecologicalcharacter- plays roughlyparallels the divergencein dive isticsof their respectivehighland refugia. The displays(Stiles and Orfiz-Crespounpubl. data). smallestand most distinct suchrefugium was The divergencebetween scintilla and ardens that on Volcfin Pofis and Volcfin Barba, and the is less easyto explain, especiallyas the distri- proto-fiammulapopulation there was probably bution and ecologyof the latter are so poorly the smallestand subjectedto the most intense known: ornithologically,the Serrania de Ta- selection.It haslong been a basictenet of pop- basar• is amongthe leastknown areasin Pan- ulation biology that evolutionaryresponses to ama (E. Eisenmann pers. comm.). It is con- selectionand divergenceproceed most rapidly ceivablethat scintillabreeds on the western part in small populations (e.g. Mayr 1963). Thus, of this range; contactbetween the two forms the greater divergence of simoni relative to duringthe breedingseason should not be ruled fiammulaand torriduswould be expectedon the out. For middle-elevation birds, the gap be- basis of the probable evolutionary history of tween Volcfin Chiriqui and the Serrania de Ta- this population. basarfihardly seemscommensurate with the Is gene flow occurringbetween these pop- degreeof divergencebetween scintilla and ar- ulations at present?This questionis difficult dens. This barrier may have been more pro- to answer with the available data. The proba- nouncedin the past, however, or may have 324 F. GARYSTILES [Auk, Vol. 100

persisted for a long time, to judge from the displaysof the northern Selasphorusand their striking degree of divergence in other groups closerelatives in the genera Archilochus,Stel- (e.g. Chlorospingus,Pselliophorus) between the lula, and Calypte (Stiles and Ortiz-Crespo in sametwo ranges.Historical factors,rather than prep.). presentecological conditions, must have played a dominant role in producingthis situation. ACKNOWLEDGMENTS As far as I am aware, the specimenof S. "un- derwoodii" is unique: no other hybrids be- I am indebted to the following institutionsfor fi- tween scintillaand any member of the fiammula nancial support: the American Museum of Natural complexhave ever been observedor collected. History; the Consejo de Investigacionesde Ciencia y Tecnologia(CONICIT); and the Vicerrectoria de The rather frequent hybrids between northern Investigaci6n,Universidad de Costa Rica. My visit Selasphorusand members of related genera to the British Museum was made possible by the (Archilochus,Stellula, Calypte) tend to occur International Council for Bird Preservation, espe- mostlywhere one speciesis rare and/orinvad- ciallyA. W. Diamond.The Organizationfor Tropical ing the range of another (Banks and Johnson Studies, the Serviciode ParquesNacionales, and the 1961,Lynch and Ames 1970,Wells and Baptista management of Pensi6n La Georgina provided lo- 1979). It is likely that a century ago deforesta- gisticalsupport and accommodations.N. K. Johnson tion was still advancingup the slopesof Volc•n and B. L. Monroe, Jr. made helpful commentson the Irazti, breachingthe band of forest that prob- manuscript. I thank L. L. Wolf, J. E. S•nchez, and R. ably onceseparated the breeding areasof scin- G. Camposfor help in the field, and the late Eugene Eisenmann, to whom I would like to dedicate this tilla andfiammula. The factthat no hybrids have paper, for his interest and encouragement.In the been reportedsince may mean that a possible courseof this study I have examinedthe specimens burst of hybridization and perhaps competi- of Selasphorusin the following museums(numbers tion as contactwas being establishedmay have of specimens examined in parentheses):American selected for refinements in microhabitat and Museum of Natural History (100), British Museum perhaps flower choice that reduced the fre- (Natural History) (32), Louisiana State Museum of quency of interspecific encounters.I know of Zoology (15), Museo de Zoologia, Universidad de no locality where the two speciesbreed sym- Costa Rica (13), United StatesNational Museum (42), patrically at present, although they may ap- and Western Foundation of Vertebrate Zoology (10). To these institutions and their curators,my sincere proach each other closely:in November 1971 I thanks. found apparently territorial males of scintilla

and fiammula at different sites, separatedby LITERATURE CITED less than 2 km and 100 m elevation, near Tierra Bianca (ca. 2,100 m) on Volc•n Irazti above Car- BANKS,R., & N. K. JOHNSON. 1961. A review of tago. North American hybrid hummingbirds. Condor At this time, it seems rather premature to 63: 3-28. attempt a detailed assessmentof the relation- BENT, A.C. 1940. Life histories of North American ships between the northern and southern cuckoos,goatsuckers, and their allies.Bull. U.S. Natl. Mus. No. 176. groupsof Selasphorus.The modificationsof the BERLIOZ,J. 1949. Le polymorphismschez les tro- outer primary and rectricesof scintillaand ar- chilides. Pp. 3-6 in Ornitologie als biologische densseem fairly similar to thoseof the northern Wissenschaft(E. Mayr and E. Schfiz, Eds.) Hei- S. platycercus;the bottom sound of the dive delberg,Germany, Carl Winter. displayof the latter is strikinglysimilar to those CARRIKER,M. A., JR. 1910. An annotated list of the of membersof the fiammulacomplex (Bent 1940, birds of CostaRica, includingCocos Island. Ann. Ortiz-Crespo1980). Thus, it is not improbable Carnegie Mus. Nat. Hist. 6: 314-915. that, of the northern group, platycercusis the LYNCH, J. F., & P. L. AMES. 1970. A new hybrid most closelyrelated to the southernSelaspho- hummingbird, Archilochusalexandri x Selas- rus, as would be expected on geographical phorussasin. Condor 72: 209-212. MAyR, E. 1963. species and evolution. grounds. Details of these relationships,how- Cambridge,Massachusetts, Belknap Press, Har- ever, will only be elucidated by more compre- vard Univ. hensive data, including sonagrams,on the dis- ORTIZ-CRESPO,F. I. 1980. Aspectsof the behavior play repertoiresof all of the southern species and ecology of Selasphorushummingbirds in (especiallyardens) and the completionof a de- Berkeley, California. Unpubl. Ph.D. disserta- tailed analysis, currently in progress, of the tion. Berkeley,California, Univ. California. April1983] SelasphorusSystematics 325

PA¾•œ,R. B. 1973. Mechanisms and control of molt. 1982. The aggressiveand courtshipdis- Pp. 104-157in Avian biology,Vol. 2 (D. S. Far- plays of the male Anna Hummingbird. Condor ner and J. R. King, Eds.). New York, Academic 84: 208-225. Press. WELLS,S. g., & L. F. BAPTISTA.1979. Displaysand RmcwA¾,R. 1911. The birds of North and Middle morphologyof an Anna x Allen hummingbird America. Bull. U.S. Natl. Mus. Vol. 150, Part 5. hybrid. WilsonBull. 91: 524-532. SLVD, P. 1964. The birds of Costa Rica: distribu- WœTMORœ,A. 1968. The birds of the Republic of tion and ecology. Bull. Amer. Mus. Nat. Hist. Panama,part 2. SmithsonianMisc. Coil. Vol. 150. Vol. 128. W•LL•aMSO•, F. S. L. 1956. The molt and testis STILES,F. G. 1972. Age and sex determinationin cycleof the male Anna Hummingbird.Condor Rufousand Allen hummingbirds.Condor 74: 25- 58: 342-366. 32. WOLF, L. L. 1976. The birds of the Cerro de la 1973. Foodsupply and the annualcycle of Muerte region, Cordillerade Talamanca,Costa the Anna Hummingbird.Univ. Calif. Publ.Zool. Rica. Amer. Mus. Nat. Hist. Novitates No. 2606. Vol. 97. , F. G. STILES,& F. g. HAINSWORTI-I. 1976. 1980. The annual cycle in a tropical wet The ecologicalorganization of a tropical high- forest hummingbird community. Ibis 122: 322- land hummingbird community. J. Anim. Ecol. 343. 32: 349-379.

REVIEWERS FOR THE AUK, 1981-1982

The Auk is fortunateto benefit from the servicesof many individuals who act as reviewersof manu- scripts that are submitted. Their efforts are considerable,and their care and constructivenesscontinue to impressme as an Editor and as a sometimeauthor. The individuals listed below helped make publication of a journal with high scientificand scholarlystandards possible; my thanks to all of them. Individuals who have contributedreviews of two or more manuscriptsare indicated by an asterisk. Kenneth P. Able*, Ralph Ackerman, Curtis S. Adkisson*, Alan D. Afton*, David G. Ainley*, Rauno V. Alatalo*, S. D. Albon, Thomas Alerstam*, Dean Amadon*, A. Binion Amerson, Jr., Peter L. Ames, Daniel W. Anderson,Ted R. Anderson,Malte Andersson,C. DavisonAnkney*, PeterArcese, Einar Arnason*,Keith A. Arnold*, John C. Avise*, Robert O. Bailey*, StephenF. Bailey, RussellP. Balda*, David F. Balph, Richard C. Banks*,Luis F. Baptista*,George F. Barrowclough*,Thomas S. Baskett,Range Bayer*, Donald L. Beaver, JeanBedard, Jim Bednarz*,Colin Beer*,Steven R. Beissinger*,Marc Bekoff,Frank C. Bellrose,Jr., JamesF. Bendell, Sven-Axel Bengston*,Albert F. Bennett, Marvin H. Bernstein,P. Berthold, Louis B. Best, Laurence C. Binford, T. R. Birkhead*, Charles R. Blem*, Lawrence J. Blus, D. A. Boag*, Carl E. Bock*, Walter Bock*, P. Dee Boersma*,William R. P. Bourne, Mark S. Boyce, John H. Brackenbury,Jack Bradbury, David Bradley*,Richard A. Bradley*,Eliot Brenowitz,I. Lehr Brisbin, M. Brooke,Lincoln P. Brower,Jerram L. Brown,Richard G. B. Brown*,Alan H. Brush,D. M. Bryant*,Paul A. Buckley,Jeffrey T. Burns,Edward H. Burtt, Jr., Steve Butler, Donald F. Caccamise*, Thomas J. Cade*, William A. Calder, Jr.*, Thomas Caraco, Cynthia Carey*, Lynn F. Carpenter, A. J. Cav6, Eric Charnov, Diane Chronister, Ellen W. Chu, Roger Clapp*, Nicholas E. Collias*, Charles T. Collins*, Michael W. Collopy*, Edward F. Connor*, Peter G. Connors*, Michael R. Conover*, Fred Cooke, John Cooper*, Kendall W. Corbin*, J. C. Coulson*, JamesJ. Counsilman, Joel Cracraft*, Adrian J. F. K. Craig, John A. Crawford, Kenneth A. Crossner,Alexander Cruz, Thomas W. Custer*, D. G. Dawson, Paul A. DeBenedictis, Scott R. Derrickson, David DeSante, Diane De Steven, A. A. Dhondt, A. W. Diamond, Jared M. Diamond, Robert W. Dickerman*, James J. Dinsmore, Keith Dixon, David S. Dobkin, Richard A. Dolbeer, R. D. Drobney, RaymondD. Dueser, David C. Duffy, Alfred M. Duffy, Jr., Arthur E. Dunham, Erica H. Dunn, John Dunning*, Alex Dzubin, Tom Edwards, David H. Ellis, John T. Emlen, Stephen T. Emlen, JamesEnderson, John Endler*, R. Michael Erwin*, David Evans, P. G. H. Evans, Roger M. Evans*, Craig A. Faanes*, Eric Fabricius, J. Bruce Falls, D. S. Farner,Kent Fiala*,Millicent Ficken*, Scott Findlay, Richard E. Fitzner,John W. Fitzpatrick,Theodore H. Fleming, BrianK. Follett,Glenn Ford, Eric D. Forsman,Leigh Fredrickson*,Stephen D. Fretwell,H. J. Frith, Robert Fuller, Carl Gans, Kimball Garrett, A. J. Gaston, J. Edward Gates, Sidney A. Gauthreaux*, RobertGibson, Frank B. Gill*, MichaelGochfeld*, John D. Goss-Custard*,Bradley M. Gottfried*,Peter R. Grant, CharlesR. Grau, W. A. deGraw, RussellGreenberg, Crawford H. Greenewalt, Paul J. Greenwood*, T. C. Grubb, Jr., Yrj6 Haila, F. Reed Hainsworth, F. N. Hamerstrom,Jr., William J. Hamilton, III, Jeremy J. Hatch*, Linda Heald, Dennis Heinemann*,Charles J. Henny*, CarlosM. Herrera, Olavi Hild6n, Wayne (continuedon p. 334)