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Reproductive Biology and Vocalizations of the Horned Guan Oreophasis Derbianus in Mexico ’

Reproductive Biology and Vocalizations of the Horned Guan Oreophasis Derbianus in Mexico ’

The Condor974 15-426 0 The CooperOrnithological Society 1995

REPRODUCTIVE BIOLOGY AND VOCALIZATIONS OF THE HORNED OREOPHASIS DERBIANUS IN MEXICO ’

FERNANDO GONZALEZ-GARCIA Institute de EcologiaA.C., Apartado Postal 63, Xalapa, Veracruz,C.P. 91000 Mfixico

Abstract. Reproductive biology and vocalizations of the (Oreophasisder- bianus)were studied in the El Triunfo BiosphereReserve in , Mexico. The nest and eggsare described here for the first time. The Homed Guan apparently has a polygynous mating system. Males make at least five different kinds of vocalizations. Females produce seven or eight different types of calls, which are guttural compared with those of males. One female took 2.81 (k-0.40) incubation recessesdaily during 16 days of observation, and individual recessesaveraged 32.9 (+ 13.1) min. Incubation sessionsaveraged 191 min * 44.6. The incubation period was estimated to be 35-36.5 days. Likely predators of Homed Guan eggsare described. Suggestionsfor the conservationof this speciesand its are presented. Key words: Oreophasisderbianus; vocalizations:mating system;; cloud forest; Chiapas.

Resumen. Se estudio la biologia reproductiva y vocalizacionesde1 Pav6n (Oreophasis derbianus)en la reservade la biosfera El Triunfo, Chiapas.El nido y 10shuevos son descritos por primera vez. Las observacionesde campo sugierenque el sistema social de esta especie estb basado en la poliginia. Los machos emiten cinco diferentes tipos de vocalizacionesy las hembras de siete a echo, las cuales a diferencia de 10s machos, son todas guturales. Durante la incubation una hembra realiz6 2.8 1 (t-0.40) recesosdiarios durante 16 dias de observation y en promedio cada recesofue de 32.9 (? 13.1) min. Las sesionesde incubation promediaron 191.13 ? 44.60 min. El period0 de incubation se estimo de 35-36.5 dias. Se mencionan a 10sprobables depredadores. Finalmente, se mencionan algunasestrategias para la conservaci6nde la especie. Palabras clave: Oreophasis derbianus: vocalizaciones;sistema social; crhcidos;bosque mesdjilode montaiia; Chiapas.

INTRODUCTION This occurs only in and The few previous studies of the Homed Guan Mexico. In the latter, it is limited to the highlands (Oreophasis derbianus) focused on description, of the Sierra Madre in Chiapas and possibly east- , and distribution (Salvin and Godman em Oaxaca (Estudillo 1979, Binford 1989, Collar 1902, Ridgway and Friedmann 1946, Fried- et al. 1992). The habitat of this species,montane mann et al. 1950, Vaurie 1968, Delacour and broadleaf or cloud forest, has a restricted distri- Amadon 1973, Blake 1977). Studies which treat bution in Mexico (Rzedowski 1978, Leopold more of its biology are those by Wagner (1953) 1950, Pennington and Sarukhan 1968) and is Andrle (1967), Parker et al. (1976) Alvarez de1 disappearing at an increasing rate as these forests Toro (1976) and Gonzalez-Garcia (1984, 1986, are felled for agriculture, husbandry, lum- 1988a, 1988b, 1994). Data on reproduction and ber and coffee plantations (Veblen 1976, Collar vocalizations are scarceand the nest and eggsof et al. 1992). the Homed Guan have remained unknown. Be- In this paper, I present observations on the cause this speciesis in danger of extinction due breeding biology and vocalizations of the Homed to and hunting pressure(Col- Guan, and also discussaspects of its conserva- lar et al. 1992) knowledge of its nest, ,and tion. behavior is of critical importance. STUDY AREA AND METHODS The El Triunfo BiosphereReserve (Diario Oficial de la Federation, 13 March, 1990) consists of I Received 1 June 1994. Accepted 19 January 1995. five core areas and a buffer zone which together

I4151 416 FERNANDO GONZALEZ-GARCiA

Angel Albino Corzo

Core Areas

Buffer Zone V Mapastepec .“...l...... ~-.. ;(/‘ ITZI.. . . . P... ’ .. ..- Reserve Boundary INSTITUTE OF NATURAL HISTORY ..j‘ osx,m STATE 0F CHIAPAS FIGURE 1. The El Triunfo BiosphereReserve, Chiapas, Mexico. The studysite is locatedin corearea I. have an area of 119,000 ha (Fig. 1). The Reserve pulifolius, Drymis granadensis var. mexicana, includes parts of the municipalities of Acacoy- Podocarpusmatudae, Ulmus mexicanum, - agua, Angel Albino Corzo, La Concordia, Ma- stroemia lineata, Oreopanax sanderianus, 0. pastepec, Villa Corzo, Pijijiapan and Siltepec. capitatus, 0. xalapensis, Nectandra sp. Ocotea The study site is located in core area I, which chiapensis,0. matudai, 0. uxpanapana, Phoebe has an area of 11,594 ha and elevations between siltepecana, P. bourgeviana, Clethra lanata, C. 700 and 2,500 m. It contains five main vegeta- matudae, C. pachecoana. Shrubs and herbs are tion types: tropical evergreen forest, pine-sweet- representedby Cavendishiasp., Centropogonspp., gum forest, coniferous forest, and lower and up- Mconia glaberrima, Senecio sp., Clusia mexi- per cloud forests.The study area is in the upper cana, Rondeletia piramidalis, Malviscus arbo- cloud forest at an elevation of 1,850 to 2,100 m. reus, Gentlea tacanensis, Fuchsia speniculata, This forest is dense,with broad-leaved evergreen Ardisia spp., and Chamaedorea spp. Ferns are trees 20 to 30 m in height and some individuals abundant, including tree ferns (Cyaihea jiilva) even taller. which reach heights of up to 15 m. Bromeliads The dominant tree speciesin the cloud forest (e.g., Tillandsia ponderosa, T. vicentina, Vriesea are: Matudaea trinervia, Quercusoocarpa, Hed- breedloveanaand orchids (e.g., Epidendrum dif- yosmum mexicanum, Ocotea spp., Conostegia forme, Maxilaria praestans,Odontoglossum cor- volcanalis,Amphitecna montana, Symplococar- d&urn) are also abundant (Gonzalez-Garcia 1984, pon flavifolium, Calyptranthessp., Glossostipula Ramirez and Gonzalez-Garcia, unpubl. data). concinna, Eugenia malensis and Zunila cucul- Data collected by the author in 1983 indicate lata (Williams 199 1, Ramirez and Gonzalez- that the maximum daily temperature averages Garcia, unpubl. data). The following tree species 15°C and the minimum daily temperature av- are also common: Dendropanax pallidus, D. po- erages5°C but temperatures down to -2°C have HORNED GUAN IN MEXICO 417 been recorded. There is a relatively dry season Percent times spent in each area and during from March to May, although rain can be abun- each recesswere compared with a Kruskal-Wal- dant throughout the year. Average annual pre- lis test (Zar 1984). A simple linear regressionwas cipitation exceeds 3.3 m. Strong winds, origi- used to test for significant differences in total nating in the Gulf of Mexico and Pacific Ocean, daily recesstime during 16 complete days of ob- are common in autumn and winter. Mist is com- servation (Sokal and Rohlf 1979, Zar 1984). mon throughout the year. Frost occursfrom Jan- were observed using 10 x 40 binoculars. uary to March. Vocalizations were recorded with a Uher 4000 This study was carried out over a period of tape recorder and parabolic reflector (recordings eight months (February to May 1982 and Feb- are deposited in the author’s sound library). A ruary to May 1983) and supplemented in 1984. chronometer was used to measure the length and Daily observations ranged from 30 min to 11.5 timing of vocalizations as well as the time spent hr. Total observation time during the study was by the females during incubation sessionsand 842 hr. recesses. At the beginning of February 1982, I made a walking survey of core area I, taking advantage RESULTS of establishedtrails, to determine sitesfrom which These observations are based mainly on the be- the Horned Guan could be observed and re- haviors of one male (referred to hereafter as “the corded. Once the first individuals were located, male”) and three or four females which were efforts were focused on following the birds to found in the same area in 1982, although data record their behavior continuously. Two blinds are included on some of the 23 additional in- were built to observe a nest and a dust bath. dividuals (12 solitary adult males, four “pairs,” Detailed observations were made of morpholog- and three young individuals) observed in other ical and characteristicsin order to dis- trails of the reserve. tinguish individuals. To determine the age of Sexual dimorphism. Without the aid of vo- young individuals, particular attention was paid calizations and behavior, the sexescannot be re- to the size and development of the horn for com- liably separated under field conditions. How- parison with data published by Alvarez de1Toro ever, in the hand the lengths of horn, wing, tail (1976)andGonzalez-Garcia (1986, 1988a). Nests and tarsus of males average longer than those of were located by following the incubating females. females (Vaurie, 1968). On the majority of oc- The polygynous mating system was deter- casions when it was possible to compare adult mined by using characteristics which differed males and females directly, the difference in horn among the individuals. One male was identified size was slight. In only two pairs (out of the seven by the presenceof an incomplete in the or eight observed) was this difference easily not- center of his tail. Females were distinguishedfrom ed, in one pair the horn of one male was esti- the male by their calls and from each other by mated to be approximately 6 cm long (well-de- the following characteristics:Female 1, discon- veloped adult), while that of the female was ap- tinuous white band on the tail; Female 2, dis- proximately 3-4 cm. This difference in horn size continuous white band on the tail (probably same may also represent individual or age variation individual as Female 1); Female 3, left side of rather than sexual dimorphism. the lower mandible without ; Female 4, Breeding season and mating system. The no distinguishing marks. breeding seasonbegan in early February and con- Two female Horned Guans were observed at tinued until the beginning of June. This period their nests during incubation, and time budgets was initiated by “mooing” of the males (de- on various activities were recorded. The con- scribed below under Vocalizations). According stancy of incubation, i.e., the percentage of the to my observations in 1982, the Homed Guan day that a spendson the eggs,was calculated exhibits serial polygyny, the male pairing with following Skutch (1976). One nest was moni- different females in succession(see Table 1). tored for 24 days, including watchesof over 8 hr The male and the first female (first pair) were on each of 16 days; the other for 10 days (watches observed on three different days during the mid- over 8 hr on four days). The first nest was watched dle of February. The second pair was seen on on average from 07:30 (06:30 on four days) to four different days about the middle of March. 17:40 hr (after 18:00 hr on 10 days). It is important to note that this second pair fe- 418 FERNANDO GONZALEZ-GARCiA

TABLE 1. Observationson one male and four female Homed Guam during courtshipin 1982 in the El Triunfo BiosphereReserve, Chiapas, Mexico.

FCZtl&S Date 1982 1 2 3 4 Male I Remarks

5 Feb. X Solitary male. 6 Feb. X Solitary male. 9 Feb. X X First pair. 14 Feb. X First pair; copulation. 11 Feb. :: X First pair; copulation. 20 Feb. X Solitary male. 26 Feb. X Solitary male. 9 Mar. X Solitary male in dust bath. 10 Mar. X Solitary male. 1l-l 2 Mar. X One Homed Guan (8 or 9) encoun- tered each day by male. 14 Mar. X X Second pair; probably Female 1 in courtship again. 17 Mar. X X Second pair. 18 Mar. X X Second pair. 20 Mar. X X Second pair. 21 Mar. X X Third pair. 23 Mar. X Solitary male. 25 Mar. X X Third pair. 26 Mar. X X Third pair. 27 Mar. X X Third pair. 28 Mar. X X Third pair. 29 Mar. X X Third pair. 30 Mar. X X Third vair: covulation. 31 Mar. X X Third pair: double copulation. 1 Apr. X Solitary male. 2 Apr. X X Third pair. 4 Apr. X Third solitary female. 5 Apr. X X Fourth pair. 6 Apr. X Female 3 on the nest. 7 Apr. X X Female 3 on the nest. Solitary male. 8 Apr. X X X Female 3 on the nest. Fourth pair; Female 4 in the dust bath. 9 Apr. X X Two females in dust bath (3 and 4). 10 Apr. X X Female 3 on the nest. Solitary male. 11-14 Apr. X Female 3 on the nest. 15 Apr. X X X Female 3 on the nest. Fourth pair. 16 Apr. X Female 3 on the nest. 17 Apr. X X Female 3 on the nest. Solitary male. 18 Apr. Female 3 on the nest. 19 Apr. Female 3 on the nest. 20 Apr. X X Female 3 on the nest. Fourth pair. 21 Apr. Female 3 on the nest. Eggscollected and substituted. 22 Apr. Female 3 on the nest. 23 Apr. Female 3 on the nest. 24 Apr. Female 3 on the nest. 25 Apr. Female 3 on the nest. 26 Apr. X Female 3 on the nest. 21 Apr.-l May X Female 3 on the nest. 2 May X Substitutedeggs of female 3 missing. 10 May Two chicks hatched in captivity. HORNED GUAN IN MEXICO 419

TABLE 2. Behavioral contexts for different types of vocalizations of the Horned Guan during the breeding season.

Context Female calls Male calls

Aggressive au,au,au raauuu &h-woo-ah bill clacking Alarm gra, gra, gra, gra bill clacking bh-woo-ah Nesting gat, gat (like a sneeze) Courting guurk, guurk, guurk hum; hum,hummm;hum,hummm; hum,hummmmm. guauuu, guauuu, guauuu rib-woo-ah garr, garr, garr, garr brief “teeth grinding”; trrr with Spanish guaak, guaak, guaak sound r).

Mating gra, gra, gra, gra garr, garr, garr, dh-woo-ah guurk, guurk, guurk guauuu, guauuu,guauuu gra, gra, gra gra Dust bathing gat,gat guurk, guurk, guurk hum; hum,hummm;hum,hummm; hum,hummmmm. Territoriality au,au,au . . . . . raauuu hum; hum,hummm;hum,hummm; hum,hummmmm. dh-woo-ah bill clacking bill clacking dh-woo-ah Comfort activities gat, gat gat, gat; trrr Flying gra, gra, gra, gra bh-woo-ah Courtship feeding guurrk, guurk, guurk hum; hum,hummm;hum,hummm; hum,hummmmm. guauuu, guauuu, guauuu bh-woo-ah trrrr

male was probably the first female observed in zations were made by either participant. It was February, yet it was courting with the same male not possibleto determine the sex of the intruding almost one month later. This probably means bird, as it quickly retreated in silence on both either that it courted but did not mate in Feb- occasions. ruary, or that it mated but its first nesting was Territorial behavior was observed in more de- unsuccessful. The third pair was observed in tail between two females on 9 April (Table 1). courtshipon nine almost full days, from 2 1 March Female 3 (which was nesting) encountered Fe- until 2 April; they copulated once on 30 March male 4 (which was courting with the male) at a and twice on 3 1 March, and its nest was found dust bathing site. Female 3 took up a position six days later and monitored during the following similar to that used by alarmed males (neck 24 days. The fourth female was observed in stretched, head pointing downward, see Andrle courtship with the male three days after he was 1967 and Delacour and Amadon 1973) and ap- last seen courting Female 3 (Table 1). proachedFemale 4, several times uttering strong Territoriality. The male established its court- and deepguttural calls (Table 2). Female 4 opened ship territory along a stream and its tributary. its , but made no sound. Although the two This territory had an estimated length of 500- were quite close, they made no physical contact. 600 m. It included at least two small valleys, but This encounter lasted 15 min. Then both females the exact width could not be determined owing walked away, Female 3 to its nest and Female 4 to the difficulty of following the male in the for- started off in the same direction but was then est. lost. Defense of courtship territory by males was Vocalizations. One of the most important dif- observed on two occasions(in the same site, see ferencesbetween the sexesis their vocalizations Table 1) on 11 and 12 March. The defending (Table 2). Males make at least five different kinds male threatened the intruder by beating its wings, of vocalizations. The first is a very deep, slow spreadingits tail and stretchingits neck forward, and soft “mooing,” similar to that of the Great but there was no physical contact. No vocali- (Crax rubra) (Andrle 1967, Parker et 420 FERNANDO GONZzkLEZ-GARCiA al. 1976), but still more similar to that of the Most are made in responseto the calls of males, Northern (Cruxpauxi) (De- with others made during territorial defense (Ta- lacour and Amadon 1973; pers. observ.). This ble 2). call is characterizedby seven notes, a single brief The first call can be interpreted as a guurk, hum followed by six paired hums (the second in guurk, guurk, . . . or guauuu, guauuu, guauuu, each pair more prolonged, especially in the final each note repeated 35 to 40 times per minute (n pair) (Table 2). This call, which can be described = 10). These vocalizations are produced when as hum; hum, hummm; hum, hummm; hum, the female is approaching a courting male. The hummmmm, is repeated an average of 3.28 f call has an echoing quality and may be an in- 0.66 times per min (n = 1,302, range: 2.0-4.75). vitation to the male to copulate. The dh-woo-ah Each call has an average duration of 7.18 set (n call is similar to the male’s call, but shorter and = 1,850). The time between the end of one call deeper. Mandible-clacking is given in a similar and the start of the next varies depending on the context to that of the males, but is more guttural. bird’s activity. During continuous calling, the av- There is another call similar to the grunt of a pig erage intercall length is 14.58 + 14.95 set (n = or the alarm call of the Neotropic Cormorant 103, range: 5-141). A male can emit this of (Phalacrocorax brasilianus). A further call emit- call for more than an hour. ted while flying sounds like a hoarse gra, gra, Males make this call either standing or squat- gru, gru (Table 2). ting crosswiseon a branch. When in a squatting One call used to defend territory sounds like position the neck takes an “S” shape, the wings au, au, au, . . . ruaaauuuu. Calls are louder than are held slightly drooped, and the tail is either those of males (Table 2). held straight out or resting on the branch. In a Courting behavior. The first courting calls are standing position, the neck is partially stretched, given at the beginning of February and the last the wings held tight over the sides, and the tail at the end of May. Courtship display is not elab- may either hang straight down or be held at “rest- orate. The encounter between the male and fe- ing position” (45” down with respectto the hor- male usually occursin fruiting trees. On meeting izontal body axis). During the call the throat and for the first time, the two rub necks, during which the upper part of the breast expand and contract both are silent. The male then makes short flights with each note, expanding to the maximum in from tree to tree, “mooing” continuously, some- the last note. The throat doesnot attain the shape times for more than an hour. The female may of a wattle as assertedby Wagner (1953) but it perch for up to an hour without responding, is intensely red, at least during the breeding sea- sometimes eating fruits or preening. A little later son. it respondsby flying toward the male. The male The second type of call made by the male is then moves to another tree and continues moo- stronger and consistsof mandible clacking. The ing. During some of its flights the male emits its sounds are somewhat similar to those made by dh-woo-ah call (Table 2). the Keel-billed Toucan (Ramphastus sulfura- The male and the female spend little time to- tus). Generally, after clacking the beak, the male gether. When the birds are near each other, the emits a third call which soundslike a hoarse ah- male perches higher than the female. As court- woo-ah. These calls are accompanied by clacking ship progressesthey spend more time together. of the beak and apparent restlessnessexhibited They may be in the same tree, but apart from by walking among the branches. Then it sud- each other, or in adjacent trees. As part of the denly stretchesits neck forward and downward courtship the male descendsto the ground and (in a motion similar to regurgitation), opens its calls to the female to offer it green leaves or to bill widely, and emits the explosive, deep and lead it to the dust bathing site. hoarsethird call. The male’s dh-woo-ah is stron- The male was observed courting three or four ger than the similar call made by females. females and was observed from three to nine The fourth call is a brief trrr, like that produced days with each female (Table 1). This was best by grinding the teeth strongly, or running a pencil documented with Females 3 and 4. along the teeth of a comb, but deeper. The fifth The data suggestthat one female (number 1 is gut gat, resembling a human sneeze. and 2 in Table 1) participated in two courtships Females produce seven or eight different calls. about one month apart, perhaps due to loss of All are guttural compared with those of males. her first clutch. This suggeststhat each female HORNED GUAN IN MEXICO 421

may be able to start courtship again if the breed- Guan feedsthe female several times per day dur- ing seasonis not too far advanced. ing courtship. The quick head movements char- Copulation. The six copulations observedtook acteristicof other Cracids(Flieg and Dooley 1972) place on thick (larger than 8 cm diameter) hor- were not observed during courtship feeding or izontal branches of fruiting trees. The female in- under conditions of stress.The only movement vites the male to copulate by guttural calling (gra, observed was a slow turning of the head to one gra, gra; garr, garr, garr; guurk, guurk, guurk), side when the male was feeding the female. This followed by an echo-like call (guauuu, guauuu, occurson branchesand sometimeson the ground. guauuu) (Table 2). On branches,it takes one of three forms. (1) The The first copulation observed was on 14 Feb- male swallows fruit and moos to the female. The ruary 1982 at 17:00 hr and took place in a Nec- female approaches the male and eats the food tandra sinuata tree. The second copulation was which the latter regurgitates.(2) After eating many on 17 February 1982 at 11:OOhr in a Dendro- fruits or green leaves in a tree, the male flies panax populifolius tree. The third occurred on toward the female and upon arriving makes the 30 March 1982 at lo:45 hr in a Conostegia vol- bh-woo-ah call and regurgitates(fruits are regur- canalis tree. The fourth and fifth copulations, gitated one at a time). (3) When the two birds involving the same pair, both took place on 31 are together in the same fruit tree the male picks March 1982 at 09:35 and 11:50 hr in a Conos- fruit from branchesand passesthem directly into tegia volcanalis tree. An additional copulation the female’s mouth. was observed on 30 April 1983 (Rafael Solis, The male also fed the female green leaves and pers. comm.). Based on the five copulations I grit several times in the dust bath. One time the observed, the general pattern is as follows. The male gave the female 8 to 10 fruits of Nectandra female respondsto the call of the male, which is sinuata (30 x 20 mm each) and 20 to 25 fruits in the upper branches of the tree, by moving to from either Dendropanaxpopulifolius(8 x 9 mm) branchesbeneath it and remaining perchedthere. or Conostegiavulcanicola (8 x 7 mm). The male approachesthe female in two or three Nest and eggs. The first nest was found on 6 jumps, showing aggressionin its movements and April 1982 at an elevation of 2,070 m on the emitting an dh-woo-ah with each jump (except trail to Palo Gordo, northwest of the El Triunfo on the first copulation of 31 March). Once to- field station. It was 24.1 m above the ground in gether, the male mounts the female and grasps a Matudaea trinervia tree. The second nest was the upper part of its neck with its bill, while found on 21 April 1983 on the same trail and at opening its wings slightly to maintain balance. the same elevation in a Clethra lanata tree at a The female lifts its tail and the cloacas come height of 16.7 m. together. Copulation lasts only a few seconds. As nesting sites, thesetwo trees shared several The male dismounts and walks slowly among characteristics.They were both tall (28 and 18 the branches, sometimes eating fruit, and then m respectively), relatively isolated and near a flies to another tree. The female remains on the ravine with a slight slope and a flowing stream. same branch for some minutes and then flies Their few branches provided ideal sites for the after the male. accumulation of leaf litter and the establishment After copulation, the male continues its court- of bromeliads, orchids and vines. ship calls and every few seconds scratches its Each nest consisted of a shallow depression, perch with its feet while beating its wings and apparently produced by the weight of the bird, tail synchronously against its body and nearby in a heap of leaves, bromeliads, orchids, and plants. This display, which may be an invitation vines. Unlike other Cracids, no material foreign to nest, was observed for the first time when the to the site, such as green leaves, small branches male was on a diagonal tree trunk which was or sticks,were found in the nest. However, some covered with bromeliads, orchids and leaf litter. dry bromeliad and orchid leaves, as well as feath- The female stayed near the male and emitted ers from the back and breast of the female, were guurk, guurk, guurk calls. On other occasions, found. The first nest measured 30 x 32 cm and the male could only be heard performing these the second33 x 36 cm. Both were oval and small movements but not seen. in relation to the size of the adults. Feeding behavior during courtship. As with As do most Cracids, the Homed Guan pro- other members of the Cracidae, the male Horned duces a clutch of two white eggs with slightly 422 FERNANDO GONZALEZ-GARCiA

TABLE 3. Time spent (in minutes) and frequency of visits to each area (number and percentage)by a Homed Guan femaleduring recesses from incubation(see text).

Number of recesses= 46 First Second Third Foraging MeaIl % MeaIl Mean areas (min) SD n (times) bin) SD n &kes) (min) SD n A (NE) 33.0 12.3 : 50.0 36.8 13.7 14 81.5 34.0 16.4 7 50.0 B (SE) 39.3 10.9 37.5 26.0 - 1 6.25 32.5 3.54 2 14.28 C (SW) 27.0 2.83 2 12.5 13.0 - 1 6.25 21.2 4.60 5 35.71

rough texture and subelliptical shape. The first 11.26 min (range 15-53; n = 19). These excur- two eggs measured 84.6 mm x 58.9 mm and sions were made exclusively to feed. The second 83.7 mm x 57.7 mm. The eggs of the second recesswas between 11:22 and 15:05 hr, averaged clutch measured 85.0 mm x 57.0 mm and 82.0 34.16 + 13.1 min (range 13-74; it = 24), and mm x 60.0 mm. was divided between feeding and dust bathing. Incubation period. The incubation period in The last recess,when it took place, was between the first nest, occupied by female 3, was esti- 14:37 and 18:09 hr, averaged 28.1 -t 12.54 min mated as 35-36.5 days. Between 31 March and (range 1 l-64; n = 17) and was spent feeding. the discovery of the nest on 6 April, the female There is no difference in daily recesstime as was either absent or by herself in the area. It was incubation advances (r = -0.46, n = 16, P > observed only on 2 and 4 April (Table 1). On 0.05,Y=118.71-2.19X,t=-0.14,P=0.050). the morning of 4 April, it took a dust bath and During 22 days of observation, this female bathed stayed for 4145 hr in or around the dust bath site, 16 times, including two days in which it bathed where it ate green leaves and fruits; after that it twice in the same day. The male did not approach walked away and disappeared in the trees where the nest during incubation. the nest was later found. This period is too long The directions of flight and areas visited by to be an incubation recessand thus she was not the female are indicated by directional abbre- incubating that morning. The bird was followed viations NE, SE and SW in Table 3. The female to her nest on 6 April, when it appeared to be had a significantly greater preferencefor area NE incubating. It incubated its own eggs until 21 (Kruskal-Wallis; H = 9.0; P < 0.025; df = 2; II April, on which date they were replaced with = 46) which she visited primarily during the eggs (see beyond). The Homed midday excursions. Guan eggshatched in captivity on 10 May. If it Behavior at the nest.There was a single, 14 cm laid the first on the afternoon of 4 April, the diameter horizontal branch, without any leaves, maximum duration of the incubation period on which the female landed prior to moving onto would be 36.5 days. If it started on 6 April, the the nest. On three occasions the female added minimum duration of the incubation period is dry orchid and bromeliad leaves in the nest dur- 35 days. ing incubation. Incubation sessionsand recesses.In 24 days, I During incubation the female behaved as fol- observed 38 incubation sessionsand 60 recesses lows. (1) Gular fluttering was done with the beak on the first nest. In 16 days of continuous ob- slightly open and the neck retracted or stretched. servation, total daily incubation time averaged This movement was observed five times toward 191.13 f 44.60 min per day (range 123-299; n the end of the incubation period, once lasting up = 38; total minutes 7,263), whereas total daily to one hour. (2) When there were strangenoises, recessesaveraged only 93.76 -t 30.6 min per day the female assumed an alert position with its (range 30-146; n = 16; total minutes 1,483). The neck completely stretchedout and looked in the calculated constancy of incubation was 84.9%. direction of the noise, cocking its head in order The female left the nest an average of 2.8 1 f to do so. (3) It stretchedits neck and opened its 0.40 times per day (n = 16) for an average of beak wide in what looked like a yawn (n = 4). 32.9 f 13.1 min per recess(range 13-74; n = (4) It preened, generally beginning with its wings 46). The first recessoccurred in the morning be- and following with its breast, back, rump and tween 07:50 and 11:39 hr and averaged 32.8 f tail; to preen its belly, scratchits face, or stretch, HORNED GUAN IN MEXICO 423 the female always stood up or briefly left the nest. Predators.Little is known about the predators (5) On three occasions, it sunned with one or of the Homed Guan. Wagner (1953) suggested both wings stretched out. (6) Infrequently, it that the Tayra (Eira barbara) is the main pred- caught small flying insects. ator. In the El Triunfo Reserve, other mammals The behavior of the female on the secondnest, which may prey upon adults, young and eggsof found on 21 April 1983, was similar to that of the Homed Guan include Kinkajou (Potosfla- the female observed on the first nest. I observed vus),Coati (Nasua narica), Ring-tail (Bassariscus the second female for nine days; the nest was sumichrasti), Gray Fox (Urocyon cinereoargen- observed continuously for over 8 hr on each of teus), Jaguar (Panthera onca), Cougar (Puma three days. The female left the nest 3.23 f 0.6 concolor), Margay (Leopardus wiedii), Ocelot (n = 3) times each day. Recessesaveraged 36.47 (Leopardus pardalis) and Jaguarundi (Herpail- + 24.67 min (range 16-132; n = 21). An average urusjagouaroundt). My observationssuggest that of 199.1 + 72.9 min (range 100-360; IZ = 11) the Emerald Toucanet (Aulacorhynchusprasi- was spent on the nest between recesses.The cal- nus) and the Fulvous (Strixfulvescens)may culated constancy of incubation was 84.5%. be predators of the eggsand the chicks, respec- Captive preservation. The nests and eggs de- tively. The former was observed taking a pair of scribedabove are the first reportedfor the Homed large white eggsfrom a nest of a Homed Guan. Guan. Because of the critical situation for this On one occasion (16 March 1982, 14:20 hr) my species with respect to survival and conserva- field assistantand I heard a strongflapping sound tion, it was decided to substitute the eggsof both in the forest subcanopy, and we could only see clutches with unfertilized eggsof Crested Guan a Homed Guan’s tail as it flew by. At the same (Penelopepurpurascens). This allowed the con- time, feathers were scatteredin the air. We ob- tinued observation of the incubating females and served an Emerald Toucanet at the nest, where the beginning of a captive breeding program. The it picked up an egg and flew away with it. The eggsin the second nest were switched during an other egg was evidently broken in the nest be- absenceof the female. Observations on this nest causetwo toucans returned and each took a piece were terminated at this point. of shell. I believe the Homed Guan was chased In both cases, the eggs were transported to from its nest. Finally, we also observeda Fulvous Mexico City and incubated by a female Wild Owl trying to catch a young (Pe- (Meleagris gallopavo). The eggsfrom the nelopina nigra). first nest hatched on 10 May 1982 and those of the second on 24 May 1983. The latter weighed DISCUSSION 94.1 and 96.7 g, respectively. This part of the Salvin (1860) assertedthat in the Homed Guan program was successful;the four birds are still “the female differs in no way except in being in captivity. From this stock,at least 15-20 young rather smaller in size and in having the crest on have been born. the head rather shorterand more tapering.” Vau- The eggsthat were substituted for those of the rie (1968) stated that the horns of males average Homed Guan on 2 1 April 1982 disappeared 11 5 mm longer. In the field, this differenceis usually days later, either during a recessor possibly when not discemable; vocalizations and behavior are the female was driven from the nest. When ob- the most reliable means of separating the sexes. servations of this nest began on 2 May, the fe- Based on data from Homed Guans reared in male was absent. Later it returned, but instead captivity (Alvarez de1Toro 1976, Gonzalez-Gar- of settling on the nest, it began to scratch and cia 1986, 1988a), I estimate that the female at- disturb it with its feet. It repeatedly entered and tending the first nest was adult (two or three years left the nest, giving the impression that it was old, horn size 6 cm approximately) and the fe- reluctant to leave it. Then the female moved to male of the secondnest was 12 to 14 months old a branch above the nest, where it remained for (horn size 34 cm). I have seen females with an hour. I climbed to the nest and found it com- small horns being courted by males with long pletely modified and without any trace of egg horns but have never seenmales with short horns remains. Below the tree I found a small fragment courting. This suggeststhat females reach sexual of eggshell, suggestingthat the eggswere taken maturity earlier than males and probably begin from the nest. The fate of the eggswhich were reproducing in their first year, as Wagner (195 3) placed in the second nest is unknown. suggested. 424 FERNANDO GONZtiLEZ-GARCiA

Cracids are thought to be monogamous, with conditions of stress.However, the male did en- the exceptions of the Highland Guan (Delacour gage in a slow ritualized turning of the head to and Amadon 1973) and Yellow-knobbed Curas- one side (by about 45”) when feeding the female sow (Crax daubentom](Schaefer 1953; Strahl and with fruits and leaf fragments. This movement, Silva 1989; Buchholz 1989, 1991). Based on my may well be homologous to the “head flicking” observations, the Homed Guan is also polygy- of other Cracids (Flieg and Dooley 1972) and if nous. so, the courtship theory is supported. Sick (1970) suggestedthat males of the Contrary to Wagner (1953) and unconfirmed Crax may have a high natural mortality rate, reports in Andrle (1967), this speciesnests high which results in an excessof females and occa- in trees (24.1 and 16.7 m) and may be the only sional polygyny. Delacour and Amadon (1973) Cracid to do so. The nest is small, relative to the suggestedthat this tendency toward polygyny re- size of the bird, and rudimentary. sults in the males being more successfullyhunted The incubation period for the Homed Guan becausetheir frequent vocalizations make them estimated at 35-36.5 days, is most comparable easy to locate. These theories may also apply to to that of some speciesof the genus Crax, which the Homed Guan. have periods of 30 to 36 days (Delacour and For the Homed Guan, two conditions may Amadon 1973, Skutch 1976). influence the establishment of a polygynous mat- The vocalizations emitted by the male have ing system: the lack of participation by the male been reported by Andrle (1967) and Parker et al. in incubation and care of the young; and the (1976) but without indication of what function reliance on fruits and green leaves that are con- they might serve. The behavioral contexts of dif- centrated, abundant and easily accessible. The ferent calls and bill clacking are given in Table first condition gives the male time to court other 2. The fourth vocalization (trrr) which had not females, provided the females are continuously been reported before, is emitted, during court- or asynchronously receptive. When food re- ship and comfort activities, but only rarely. In sources are concentrated, abundant and easily addition, Wagner (1953) reported another call accessible,males may be able to control female made by the male which sounds like “tschia, accessto them, allowing polygyny (Emlen and tschia, tschia.” This may be homologous to the Oring 1977, Beehler 1983, Wheelwright 1983). gat, gat of the female. In my study site, some fruit specieseaten by the Homed Guan are known to be spatially clumped CONSERVATION (Conostegia volcanalis, Ocotea uxpanapana, The Homed Guan has been classifiedas rare by SymplococarponflavijXum) (Ramirez and Gon- various researchers(Sclater and Salvin 1859; Sal- zalez-Garcia, unpubl. data). vin and Godman 1902; Wagner 1953; Andrle Courtship displays are among the simplest 1967,1969;AlvarezdelToro 1976,198O;Parker within the Cracidae, lacking the elaboratenessof et al. 1976; Delacour 1977; Leopold 1977; Collar some speciesof the genera Crax and . et al. 1992). At most, only 23 individuals were The male’s scratching movements interspersed seen during my study. The world population has with synchronous beating of the wings and tail diminished as a consequenceof habitat destruc- may function as an invitation to the female to a tion, immoderate hunting and, recently, by the potential nest site. Courtship feeding, with the capture of live birds. As such, the speciesshould male feedingthe female, is common in the Homed be considered endangered. Guan, and probably in the majority of Cracid Considering its low reproductive capacity (two males, as I have also observed it in Highland eggsper year) the speciescannot endure the pres- Guans and other Cracids in captivity. suresof hunting and habitat destruction without “Quick nervous” movements of the head, a significant decreasein population size and per- characteristicof 26 speciesin nine genera of Cra- haps extinction. Effective and practical mea- cids (Flieg and Dooley 1972), may be associated sures, such as habitat protection and the devel- with courtship feeding (Stokes and Williams opment of a captive breeding program, must be 197 1) or with defense against flies and parasitic taken to protect the species. Captive breeding insects(Sick 1970, Flieg and Dooley 1972). Quick should be coordinated between interested insti- head movements were not observed in the tutions and individuals and be initiated either Homed Guan either during courtship or under by obtaining more birds and eggsfrom the wild HORNED GUAN IN MEXICO 425 or by using the birds currently in captivity (15- (Conacyt),Brehm Funds, and Wildlife Conservation 20 produced by the four from El Triunfo, as well lntemational. as a few in Mexican zoos and other private col- LITERATURE CITED lections). This captive population can play a sig- nificant conservation role as a genetic reservoir ALVAREZDEL TORO, M. 1976. Datos biologicos de1 pavdn Oreophasisderbianus G. R. Gray. Revista from which new populations can be founded Univ. Aut. de Chiapas 1:43-54. (Magin et al. 1994). ALVAREZDEL TORO, M. 1980. Las aves de Chiapas. Conservation of the cloud forest in the El Pub. Gob. Edo. de Chiapas, Tuxtla Gutierrez. Triunfo Biosphere Reserve is necessaryfor sev- ANDRLE,R. F. 1967. The Homed Guan in Mexico era1 reasons. This is a habitat of very limited and Guatemala.Condor 69:93-109. ANDRLE,R. F. 1969. Biology and conservationof the distribution in Mexico (Pennington and Saru- Homed Guan. Amer. Philosoph. Sot. YearBook khan 1968, Rzedowski 1978). Full protection 1968~276-277. would guarantee the survival of speciesthat are BEEHLER,B. 1983. Frugivory and polygamy in birds currently threatened with extinction in Mexico, of paradise. Auk 100:1-12. BINFORD,L. C. 1989. A distributional survey of the such as Homed Guan, Highland Guan, Maroon- birds of the Mexican state of Oaxaca. Omitholog- chested Ground-Dove (Claravis rnondetoura), ical Monographs No. 43. American Omitholo- Resplendent Quetzal (Pharomachrus mocinno), gists’ Union. Washington, DC. Azure-rumped Tanager (Tangara cabanisi), Jag- BLAKE,E. R. 1977. Manual ofNeotropica1 birds. Vol. I. Univ. of Chicago Press, Chicago. uar, Cougar, Tapir (Tapirus bairdii) and various BUCHHOLZ,R. 1989. Singingbehavior and omamen- amphibians and reptiles, and would help mini- tation in the Yellow-knobbed CurassowCraxdau- mize population declines for many other species bentoni. M.Sc. thesis, Univ. of Florida, Gaines- (Terborgh 1974, Smith 1976, Myers 1979, Collar ville, FL. et al. 1992, Olney et al. 1994). Humans in general BUCHHOLZ,R. 1991. Older males have biggerknobs: and Mexicans in particular are obligated to pro- correlatesof ornamentation in two speciesof cu- rassow.Auk 108:153-160. tect this biological legacy and to conduct pro- COLLAR, N. J., L. P. GONZAGA, N. KRABBE, A. grams that assurethat populations of these spe- MADRO~~ONIETO, L. G. NARANJO,T. A. PARKER cieswill not just exist, but prosper(Ramos 198 1). III, ANDD. C. WEGE. 1992. Threatened birds of More research in the El Triunfo Biosphere Re- the Americas. ICBP/IUCN Red Data Book. serve is needed to understand the biology of the Smithsonian Institution Press, Washington, DC. DELACOUR,J. 1977. Two collectionsof birds in Mex- flora and fauna. Researchcould also identify pos- ico. Avicult. Mag. 83:50-53. sible scientific, economic and tourist uses that DELACOUR,J., AND D. AMADON. 1973. are compatible with the ecosystem,but this work and related birds. American Museum of Natural must be accomplished before this valuable eco- History, New York. system disappears. Emm, S. T., ANDL. W. ORING. 1977. Ecology, sex- ual selectionand the of mating systems. Science 197:215-223. ACKNOWLEDGMENTS ESTUDILLO,L. J. 1979. Homed Guan. American I am particularly grateful to the former Instituto Na- Pheasantand Waterfowl SocietyMagazine 79:22- cional de Investigacionessobre RecursosBioticos (IN- 29. IREB). I thank Mario A. Ramos and JesusEstudillo. FLIEG,M., AND R. E. DOOLEY. 1972. Spasmodictic, who provided valuable advice on my research.My field a behavioral trait of the Cracidae. Condor 74:484. work would have been impossiblewithout the unfailing FRIEDMANN,H., L. Gatsco~, ANDR. T. MOORE. 1950. assistanceof the Solis-Galvez family, especiallyRafael Distributional check-list of the birds of Mexico. Solis Galvez and Ismael Galvez Galvez. Ismael Cal- Part I. Pacific Coast Avifauna 29. zada helped collect plants. I thank them for their as- GONZALEZ-GARCIA,F. 1984. Aspectosbiolbgicos de1 sistanceand encouragement.I also thank the Instituto pavbn Oreophasisderbianus G. R. Gray (Aves: de Historia Natural of the state of Chiapas and the Cracidae) en la reserva natural El Triunfo, Mun- Secretariade Desarrollo Urban0 y Ecologia which al- icipio de Angel Albino Corzo. Chiavas. Mexico. lowed me to work and live in the reserve. Finca Prusia Bachelor’s Thesis. Universidad Veracruzana. Fa- helped with logistic supporton several trips to the re- cutad de Biologia. Xalapa, Ver., Mexico. serve. Sonia Gallina, Albert0 Gonzalez, Victor Rico- GONZALEZ-GA&A, F. 1986. Description and devel- Gray, Salvador Manduiano. Carlos Martinez de1Rio. opment of Homed Guan’s chicks Oreophasisder- Bianca Delfosse, Patricia Escalante,Hector Gomez de bianusunder captive conditions. XIX Congressus Silva, Robert T. Andrle, L. C. Binford and two anon- Internationalis Ornithologicus. Ottawa, Canada. ymous reviewersprovided helpful comments on earlier GONZALEZ-GARCIA,F. 1988a. Crecimiento y desar- versions of this manuscript. This research was sup- rollo de1 Pav6n Oreophasisderbianus bajo con- ported by Consejo National de Ciencia y Tecnologia diciones de cautiverio. II Simposio Intemacional 426 FERNANDO GONZALEZ-GARCiA

sobre la Biologla y Conservaci6n de la Familia SALOON,O., ANDF. D. GODMAN. 1902. Aves. Biologia Cracidae. Caracas,Venezuela. Centrali-Americana, 31274-275. GONZ&LEZ-GARCIA,F. 1988b. The Homed Guan. SCL.ATER,P. L., AND 0. SALVE-L 1859. On the omi- Animal Kingdom 91:21-22. thology of . Part. III. Ibis 1:213- GONZALEZ-GARCIA,F. 1994. Behavior of Homed 234. Guans in Chiapas,Mexico. Wilson Bull. 106:357- SCHAEFER,E. 1953. Estudio bio-ecol6gico compar- 365. ativo sobrealgunos Cracidas de1 norte y centro de LEOPOLD,S. A. 1950. Vegetation zones of Mexico. Venezuela. Bol. Sot. Venezol. Cien. Nat. 15(80): Ecology 31507-518. - 30-63. LEOPOW.S. A. 1977. Fauna silvestrede Mexico. Aves SICK,H. 1970. Notes on Brazilian Cracidae. Condor y mamiferos de caza. Ediciones de1 Instituto de 72:106-108. RecursosNaturales Renovables. Mexico. SKLITCH,A. F. 1976. Parent birds and their young. MAGIN, C. D., T. H. JOHNSON,B. GROOMBRIDGE,M. Univ. of Texas Press, Austin, TX. JENKINS,AND H. SMITH. 1994. Species extinc- SOKAL,R. R., AND F. J. ROHLF. 1979. Biometria. tions, endangerment and captive breeding, p. 3- Blume Ediciones. 31. In P. J. S. Olney, G. M. Mace, and A. T. C. SMITH,R. L. 1976. Ecologicalgenesis of endangered Feistner [eds.], Creative conservation:interactive species:the philosophy of preservation.Ann. Rev. management of wild and captive . Chap- Ecol. Syst. 7:33-35. man and Hall, London. STOKES,A. W., AND H. W. WILLIAMS. 1971. Court- MYERS,N. 1979. The sinking ark. Pergamon Press, ship feeding in gallinaceousbirds. Auk 88:543- New York. 559. OLNEY,P.J.S.,G. M. MACE,AN~A.T.C. F~STNER[EDS.]. STRAHL,S., ANDJ. SILVA. 1989. Chickens of the tree. 1994. Creative conservation: interactive man- Anim. Kingdom 92:56-65. agement of wild and captive animals. Chapman TERBORGH.J. 1974. Preservationofnatural diversitv: and Hall, London. the problem of extinction prone species. Biosci- PARKER,T. A. III, S. HILN, AND M. ROBBINS.1976. ence 241715-722. Birds of El Triunfo cloud forest,Mexico, with notes VAURIE,C. 1968. Taxonomy of the Cracidae (Aves). on the Homed Guan and other species.Am. Birds Bull. Amer. Mus. Nat. Hist. 138:133-259. 30:779-782. VEBLEN,T. T. 1976. The urgent need for forest con- PENNINGTON,T. D., ANDJ. SARU~~N. 1968. Manual servation in highland Guatemala. Biol. Conserv. para la identificaci6n de 10s principales arboles 9:141-154. tropicalesde Mexico. Inst. Nat. Invest. Forestales WAGNER,H. 0. 1953. Die Hockohtihner der Sierra y FAO. Mexico, D. F. Madre de Chiaoas/Mexiko. Veroffentl. Mus. Bre- RAM&, M. 1981. Problemas involucradosen la con- men, Reihe A.-2:105-128. servaci6n. Management Todav 102:12-20. WHEELWRIGHT,N. T. 1983. Fruits and the ecology RIDGWAY,R., AND H: FRIEDMANN: 1946. The birds of Resplendent Quetzals. Auk 100:286-301. of North and Middle America. U.S. Nat. Mus. WILLIAMS,L. G. 1991. Nota sobre la estructurade1 Bull. 50 Part. 10. estrato arboreo de1 bosque mes6filo de montafia Rzawwsrcr, J. 1978. Vegetaci6n de Mexico. Limusa, en 10s alrededores de1 campamento El Triunfo, Mexico. Chiapas. Acta Botlnica Mexicana 13:1-7. SALOON,0. 1860. History of the Derbyan Mountain- ZAR, J. H. 1984. Biostatistical Analysis. Prentice- (Oreophasis derbianus). Ibis 2:248-253. Hall, Englewood Cliffs, NJ.

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