BEHAVIOR

Sound production and reproductive biology of the Highland in E1 Salvador's Montecristo Cloud Forest

Some observationsof a little-known denizen of the high elevationforests

Tom Pullen, Jr.

INTRODUCTION vationsup to 2418 meters.The studywas 4000 mm annuallyand is most abundant conducted in the zone between 1600 me- duringthe monthsof May throughOcto- HElUGHLAND GUAN , also known as ternand the peaksof thesemountains. ber (FAO 1975). Above 2100 meters, the Black Chachalaca(Penelopina The area falls mostly within the sub- much water reachesthe soil owing to nigra), a pheasant-sizedmember of the tropical lower montane wet forest life condensationon the forest canopy that family ,is a little-knowninhabi- zone as defined by Holdridge (FAO falls to the ground_ tant of denselyforested highland pine- 1975). Local residents refer to the forest oak and cloud forests of Central Amer- asthe "bosquenebuloso" or cloudforest ica. These range from southern due to the cloud tonnationsthat envelop Data collection Mexico (Oaxaca) to north-central Nicara- the mountaintopsa portionof each day. gua(A.O.U., 1983)but owing to habitat The dominant trees in this forest are ever- Data were collectedfrom April 1977 destruction,they are becomingincreas- green oaks (Quercus spp.). An abun- throughSeptember 1978 during 5-7 day ingly rare. danceof fernsoccurs and epiphytic plants visitsmade at approximatelymonthly in- This report is basedupon field ob- are conspicuouslypresent throughout the tervals.A total of 126 dayswas spentin servationsmade during 1977 and 1978 area. Much of the land lying below 2100 thefield. I observedguans while walking while the author worked in 's metershas been altered radically by hu- along the roadsand trails locatedwithin largestremaining cloud forest located at manactivity. This land is a patchworkof the area.Observations were madeduring the pointwhere El Salvador,. pasture,agricultural land, youngsecon- all hoursof the day but work was more and meet. dary forest and brushland. and mature concentratedin early morning and late Descriptionof the studyarea forestsof oak and pine(Pinu.s oocarpa). afternoon.I compileddata on singing, The climate of the area is cool and hu- displays,male-female interactions. terri- HEMONTECRISTO CLOUDFOREST sur- mid. Temperaturesgenerally range from toriality of male birds, and nestingand roundsfour mountain peaks with elc- 12ø to 18øCand precipitationis 2000- broodrearing activity of the female.

Vtewof theMontecristo mountain range showing the cloud formations Agriculturalclearing in thecloud forest -- a primarycause of habitat that typicallyenvelope the mountaintopseach morning. loss.All photos/T.Pullen. Jr.

948 American Birds. November-December 1983 servedwhistling while on the groundand in trees. The second sound can best be de- scribedas a rippingor drummingsound. It is very similarto the soundof a pieceof clothbeing forcefully torn. This soundis probablythe sameas the "loud crack fol- lowedby a cascadeof descendingnotes" describedby Land (1970). These sounds were heardduring the sameperiod as the whistle vocalizations.They were pro- duced by males gliding downward to- wardthe ground from treetops or asbirds glided from tree to tree. The drumming soundsappear to be produced by the wings. I observedclosely the production of these sounds on three occasions. It seems obvious that the "loud crack" de- scribedby Land wasproduced by a slap- pingtogether of the wingseither above or belowthe body, andthat the "cascadeof descendingnotes" following was due to vibrationof the primarywing feathersas the glided with wings outstretched. On two occasions,I clearly saw the vi- brationof feathersas a bird glided direct- ly overhead.A similar meansof sound productionin the Black Guan (Chamae- petes unicolor), a related cloud forest speciesfound in CostaRica and Panama. has been describedby Skutch (Skutch, ms. cited by Delacour and Amadon 1973).

Display behavior

Upper:posture of the adult maleprior to begin.i.g a ' 'drtontning"di.•plav glMe. Lower:posture Both whistling and drumming were of the tnale while prodttcingthe whistle vocalization. part of a displayritual occurringin small forest clearings. In such areas, a male wouldglide or climb to the top or nearthe RESULTS AND DISCUSSION octaverange". It appearsto functionpri- top of a tree on one side of the clearing, marily as the territorialsong of the male andthen, glide downwardand acrossthe HEREWAS ATOTAL of121 sightings of and was commonly heard during the clearingto a secondtree, producingthe guans.Birds usually occurred either monthsof Januarythrough May but most drummingsound as he flew. He would singly, in pairs (not necessarilyof the often during March. Males were oh- then hop from branch to branch until oppositesex), or in smallgroups of from three to five individuals. Males and females were seen together during all monthsexcept May, and sightingswere most frequent during the month of March. Most birds sightedwere males.

Vocalization and other sound production

Sound productionwas conspicuous only duringthe springmonths and then onlyin the male.Two distinctivesounds wereproduced. One, clearlya vocaliza- tion, hasbeen described by Land (1970) as beinga "long whistlesteady in vol- Female guan incubating egg in nest in the umebut risingin pitchover abouta two- Typical.foresthabitat where guans live crown of a giant tree fern.

Vol. 37, Number 6 949 Typicalglide path of the adultmale between trees during the "drumming"display. DrawingsiT. Pullen, Jr. reachingthe top of this secondtree and female for about 15 minutes before she who, throughits wildlife program,pro- thenglide downward and in the direction flushed.I returnedto thisnest again May vided material supportfor this study. from which he originally came. Often 23 and found it abandoned.The single Invaluableassistance also was given by thisflight patternwould be repeatedsev- egg was still presentand unbroken. the Fundacion Max Freund, the Peace eral timeswith the drummingsound be- Eightobservations of youngin varying Corps, the SmithsonianInstitution, the ingproduced during each glide. Between stagesof maturity were made during Museo de Historia Natural de El Sal- glides,the bird whistledat intervalsas he April, May, June,July, and November. vador,Cornell UniversityLaboratory of hoppedupward in the treesin preparation No more than two were seen with each Ornithology, and the World Wildlife for a new flight. I neverobserved a male femaleand in only one casewas a male Fund. Many individualsaided me in this producingthe whistlevocalization while sightednearby. Two of the sightings(in studyand I wishto thankespecially Fran- in flight, althoughsuch has been reported April) wereof femaleswith recenthatch- cisco Serrano. Walter Thurber, Julio by Rowley (Rowley, cited by Delacour lings that probably were less than one Martinez, Pedro Hernandez, and James and Amadon 1973). Males were seen uti- week old. Hartman. lizingthe samedisplay area day afterday but no females were observed in the area Nesting season LITERATURE CITED whilethe displayswere beingconducted. On severaloccasions, playback of a tape Dickeyand van Rossem (1938) report- A. O. U. 1983. The A. O. U. Check-list of recordingof the whistle vocalizationin ed the collection of a female in laying NorthAmerican Birds, 6th Edn. 877 pp. the vicinity of a displayingmale elicited condition in the Montecristo area on Feb- DELACOUR, J. AND D. AMADON. 1973. its immediateapproach, perhaps indicat- mary 26. Their observationplus my ob- Curassows and related birds. The Ameri- ingthat this display functions in territori- servationsof singingmales and of fe- can Museum of Natural History, New al advertisement. York. 247 pp. males nestingor accompanyingnewly DICKEY, D. R. AND A. J. VAN ROSSEM. hatchedyoung lead me to concludethat 1938. The birds of El Salvador. Zool. S. Nesting and brood-rearing behavior the probablepeak periodof incubation FieldMus. Nat. Hist., 23. 609 pp. and hatching is from late Febmary FAO. 1975. Desarroloforestal y ordenaci6n Only one active nestwas found. I ob- throughApril. Thisperiod coincides with de cuencashidrogrfificas. El Salvador. serveda femaleincubating a singleegg in the periodof peak activity of singing Zonasde vida (basadoen la labor del con- malesand is the heightof the dry season sultor),L. R. Holdridge.Informe t6cnico this nestMay 8, 1978. The nestwas lo- No. 6. catedin a virgin cloud forest area at an (FAO 1975). LAND, H. C. 1970. Birds of Guatemala. Liv- elevation of about 2050 meters. It was ingstonPubl., Co., Wynnewood,Penn. situatedabout 5 metersabove the ground ACKNOWLEDGMENTS 381 pp. in the crown of a giant tree fern {Dick- soniagigantea) growing on a southwest I WISHTO TH^lqK THœ Ministerio deAgri- --Box 1655 facing slope. I observedthe incubating culturay Ganaderiaof El Salvador Vicksburg,MS 39180

950 American Birds. Novcmbcr-Deccmbcr 198t