Corella,1993, 17(a): 111-113 DUAL SINGINGBETWEEN AN ADULTAND FLEDGLING MARBLEDFROGMOUTH

WILLIAM E. DAVIS Jr1and BRUCE M. BEEHLER2,3

rCollege of General Studies, Boston University,8Tl Commonwealth Avenue, Boston, MA 02215, USA rAssociate Research Zoologist, Wildlife Conservation International, New York Zoolosical Societv. Bronx, NY 10460 USA sPresent address: Division of , National Museum of Natural History, Smithsonian Institution, Washington, DC 20560, USA

Received 17 November I99l

INTRODUCTION an^ddiagrams (Figs 1-3) were made with a Kay CSL 4300 analysissystem implemented Dual singing includes duetting, contact calls on a Zeoi 386 computer. One and chorus singing. We report here an instance of was a fledgling with an approximately 8 cm tail, dual. between an adult and fledgling sitting crosswise on a 4 .sing.lng cm branch, approximately Marbled ocellatusin eastern 10 m above a forest floor. It uttered a monotonous seriesof ,whoo' . Since duetting by definition 'koooo' or lupuq (Figs includes only singing or calls between members -notes 1-3) which occasionally b9.?ry9 disyllabic'koo-loooos'(Figs of a mated pair, the vocalizationsreported here 1 and 2). Thb adult-bird usually sang a low-pitched ,growl; between an adult and fledgling are probably best (Figs l.and )), the fledgling singing described as contact calls. The only reports of immediately after the adult stopped dual singingor calling in the Marbled Frogmouth calling (Fig. 1), bur on one occasion the two were recorded singing at the were by Holmes (1981) who speiulated same time (Fig. 2). The 'growl' antiphonal calling by members of a paii, and by consisted of a series of low-pitched staccato Reehler e.t al. (1986) who reported group o, notes, sounding much like a stick being scraped chorus calling. We have found no repoit ofper- along a wooden picket fence. The adult bird was sistent.dual singing of an adult and fledgling of approximately any avian species. 16 m from the fledgling, on a thick bianch aboui 2.5 m from the ground. It was very dark, and there was sufficient undergrowth. so it is doubtful that the birds could see each other. The fledgling METHODS AND RESULTS continued to call while in the spotlight. The aduti bird ceased calling while _ On 15 August, 1990, at about 2000 hrs, in illuminated, and hissed Varirata National Park, near port Moresbv. when the spotlight was turned off. The birds had Papua New Guinea, we heard vocalizations from been calling for about 40 minutes prior to the two Marbled which were different spotlighting. from any which we had heard before. The habitat The fledgling sang at a rate of slightly more was old,second-growth forest and we frequently than one phrase per second (Figs 1-3), while the heard Marbled Frogmouths vocalizing. tieehler 'duetting' adult's song pulsed at a rate of about one every recorded the or dual singi-ng of two Vro second (Figs 1 and 2). The fundamental birds near our camp, and Davis and D. Heath frequency for both the adult and fledgling was found the two singing birds with the aid of a spot- about 500 hz. The amplitude of the adult song light. The recordingi were made with a Marantz remained constant, while the amplitude of the cassette recorder with a uni-directional fledgling song gradually increased-duringa song microphone. The acousticwaveform was displayed bout (Fig. 3). W.E. Davisand B. M. Beehler Dual singingin MarbledFrogmoulh Corella l7(4)

^32 9

E -)2 - Time(sec) l.l E ligLtrc L Anlllilude vs. time wave.formoJ counrersigntrtgadult and fledglittt<. J|

0 Tih€ Gec) l.Jj

Figure2. /rrl/ilul( vs. lim? warc.fo n o! sitnultancou\singi g o.[adult (nokt upproxi' nut.[] cvet tltr o! u tacond throughoti.l.55 ft@nLl periad) dnd fieIlqling (thrcc phn]rn'sot koo-loooo vuntls).

E -32 l0 5J 0 Tim' (s'c)

Iriqrrrc l. Arrzli/rkl? vs. linl('^'uvelbnn ol t'letlgling biftl ilotrory inue6ed anplitud' 'ltot1dn.\s (lrog ) \'ih !int Theshury infl&1b s ata buckgrcund noi!( ro(1 i'uttons)'

'woolook- DISCUSSION succceded, by a rapid successionof woolook notes, and anothcr tyPical call consists 'whoorJoop. to six whoorJoopo's Thc song of the Marbled F'rogmouthin Aust- o{ four 'brrrr' ralia has bcen described as: a soft but loud (Holmes 191J1);a loud high-pitched short 'kooloo kooloo kooloo' (MacGillivary 1918); ind a short barking'chuck' (Schoddeand Mason 'kooltxl' 'o(x)ce' or (Coates l9E5): six to l0 1980);wild descendinglaugh with bill clap, and a 'caw-caw' notes descending in volume and sott shori-range.low. pulsatingcall reminiscentof the 'koor-loo's(Roberts and Ingram l97li) or'coop- call of a Cane Toa d Bufo marinus uttered by both coop-coop-coop-gobblc-gobble-gobble'(Corben sexes(Hollands 1991).In New Guineathe Marbled 'gobble' and Mason 1980)' and the Frogmouth vocalizationshave becn describedas: in Schodde 'koooloo" may be added to the end of the usual a ris"ingseries of'hoooa hoooa hoooa'sometimes of trilled (Goddard in Schoddc and Mason 1980); the prired"notesfollowcd hy a rollingseries wilh tlle hill 'gobble' may be precedcd, or on occasron notesending * ith a clicksound maJc September.1993 W. E. Davis and B. M. Beehler:Dualsinging in MarbledFrogmouth 113

(several birds may call as a group) (Beehler et al. Beehler et al. 1986; pers. obs.) where groups of 1986). four to six birds may call together. This chorus singing is probably analogous to the chorus singing The song of the fledgling is similar to the 'kooloo' of kookaburras, and may be related to territorial normal notes and may be a juvenile 'growl' defence. It is possible that the dual singing version of the adult song. The of the adult between the adult and fledgling was 'practice' may be the sameas, or similar to, the 'Cane Toad' chorus song. The dual call reported by Hollands (1991). singing was more likely for contact purposes, since Marbled Frogmouths are Duetting between a male and female is found nocturnal and frequently found in dense vegeta- in more than 100 species of 32 families (Thorpe tion where they cannot see each other. I9l2), but in only eight species in New Guin-ea (Diamond and Terborgh 1963). Duetting is nru_tualor reciprocal song between a mated pair ACKNOWLEDGMENTS of birds (Armstrong 1973). The duetting may be We wish to thank Stephen Debus, Peter antiphonal where the male and female sing Fullagar, Jill and David Heath, Robert E. alternately, or the two may sing different or Lemon, Frederick Wasserman and Harry F. identical phrases simultaneously. Thorpe (1972) Recher for critically reading the manuscript. reported duetting in six speciesof owls, and it is We thank the National Geographic Society for found in all four Australian Ninox sDecies financial support of the research at Varirata (S, S. Debus. pers. comm.. 1992).The J. . _ only National Park, and we thank Robert Hillman and published report suggesting duetting for the Carla Gress who prepared the acoustic waveform Podargidaewas Holmes (1981),but Debus (pers. displays and made helpful suggestions on the comm., 1992) reports duetting (alternate bouts 'oom-oom-oom' of manuscript. the calls) in adult pairs of Tawnv Frogmouth Podargus strigoideseariy in the breed- ing season.Debus also reports call and answering REFERENCES by Australian Owlet-nightjars Aegothelels Armstrong,E. A. (1973).'A (Dover cristatus. Srudyof Bird Song.' Countersinging, another form bf dual Publications, Inc.: New York.) singing.is generallyalternate territorial singing Beehler, B. M., Pratt, T. K. and Zimmerman, D. A. (1986). 'Birds 9I_^Tul$ in adjacent territories (Armstron[ of New Guinea.' (Princeton University press: The songs of the adult Princeton.) !273.), and fledglin! 'The Marbled Frogmouths were generailv antinhirnati Coates, B. J. (1985). Birds of Papua New Guinea' Vol. (alternating.iee Fig. l). but occasionally I: Non-Passerines.(Dove Publicarions:Alderly. eld.) were Diamond J. M. and Terbough, simultaneoul (Fig. J. W. (1968).Dual singingby 2). There are reporfs of a New Guinea birds. Auk. 85:62-82. juvenile 'Bird bird (Laniarius) joining in the duetting Hinde R. A. (1969). Vocalizations.' (Cambridge of parents (Hinde 1969; Thorpe 1972), but we University Press: Cambridge.) 'Birds have found no report of persistent antiphonal or Hollands, D. (1991). of the Night: Owls, Frogmouths simultaneous singing of a fledgling and adult bird. and Nightjars of Ausrralia.' (Reed: Sydney.) Holmes, G. (1981). Thorpe (1972) reports thai young Lsniarius Field identification of the Marbled Frog- 'practise' motth. Australian Birris l5A\: 74-'/ 5. duetting, and considers this important McGillivary, C. W. (1918). Ornithologists in Norrh eueens- in the dgvelgprlrent of voice production in young lan<1.Emu l7: 180-212. birds. The fledgling frogmouth may Roberts, G. J. and Ingram, G. i. (1978). 'practising' have. beei Marbleri Frogmouth the normal call of the species, but in the Conondale Range, south-eastern Queensland. Ernz since the adult was singing very different phrases 78:4142. Schodde. R. (1980). 'Nocturnal from the young bird we doubt that the duai calline and Mason, I. J. Birds of Australia.' (Lansdowne: Melbourne.) was related to song.development. Marbled Frogl Thorpe, W. H. (1972). Duetting and Antiphonal Song in mouths often participate in chorus calling or song Btrds. Behaviozr Supplement No. 18.