SHORT COMMUNICATIONS ORNITOLOGIA NEOTROPICAL 25: 469–472, 2014 © The Neotropical Ornithological Society OBSERVATION OF A CALLING ASSEMBLAGE IN THE COLLARED TROGON (TROGON COLLARIS) Cristina Sainz-Borgo Departamento de Biología de Organismos, Universidad Simón Bolívar, Caracas, Venezuela. E-mail: [email protected] Observación de coro de llamados en el Trogón acollarado (Trogon collaris). Key words: Collared Trogon, Trogon collaris, behavior, communal calling, Trogonidae, Venezuela. INTRODUCTION (Riehl 2008). This behavior, whose function is unknown, has been reported, e.g., for several Birds participate in diverse singing aggrega- African species: Narina Trogon (Apaloderma tions, including dawn and dusk choruses narina), Bare-cheeked Trogon (A. aequato- (Kacelnik & Krebs 1982, Otter et al. 1997, riale), and Scarlet Rumped Trogon (Harpactes Penteriani & Delgado 2009), leks (Foster duvaucelii). In the Americas, it was found in 1983, Hoglund 2003), communal nuptial dis- Hispaniolan Trogon (Priotelus roseigaster), Slaty- plays (Moller 1990, Miller & Baker 2009), and tailed Trogon (T. massena), Violaceous Trogon communal roosting (Eiserer 1984, Wright et (T. violaceus), Choco Trogon (Trogon comptus), al. 2003). These aggregations may serve as Eared Quetzal (Euptilotis neoxenus), Amazo- “information centres,” evolved primarily for nian White-tailed Trogon (T. viridis), Citreo- the efficient exploitation of information line Trogon (T. citreolus), Black-headed Tro- (Ward & Zahavi 1973), or mate selection gon (T. melanocephalus), Blue-tailed Trogon (T. (Kroodma & Byers 1991), or both. Commu- comptus), Black-tailed Trogon (T. melanurus), nal calling could increase foraging efficiency and Resplended Quetzal (Pharomacrus mocinno) (Clark & Mangel 1986, Petit & Bildstein 1987) (Brosset 1983, Wetmore & Swales 1931, or be important concerning antipredator Skutch 1972, Haffer 1975, Zimmerman 1978, response, as have been reported for several Skutch 1983, Howell & Webb 1995, Riehl bird species (Griesser 2008). 2008, Johnsgard 2000, O´Neill 1974), but is A particular type of singing aggregation in unknown for the Collared Trogon (Trogon trogons, the calling assemblage, is performed collaris). by a group of 3–10, and occasionally up to 20 The Collared Trogon is a common resi- males (Collar 2001), which call repeatedly dent of humid and wet forest in several coun- while chasing each other from perch to perch tries of central and north South America 469 SAINZ-BORGO (Restall et al. 2006), from 300–2300 m a.s.l. Collared Trogons, being short, clear, and (Hilty 2003). It is one of the smallest species strong, sounding like ‘cow cow cow.’ No females of the family Trogonidae (lenght ca. 25 cm), visited the group of males during the period with partly iridescent red and green color- of my observation. The birds were obviously ation. Sexes are dimorphic. Males have a not disturbed by my presence, probably green head, breast and belly red, the chest because they are used to human presence as green with a white band, and the tail green this area of the park is frequently visited. The above with many black bands at the tip. observations were made with naked eye and Females have the head soft brown, breast and using binoculars (8x40). belly pinky to red, and the uppertail dark rufous with a black band at the tip (Meyer de DISCUSSION Schauensee & Phelps 1978, Hilty 2003). This species feeds of arthropods and fruit (Remsen To the best of my knowledge, this is the first et al. 1993). Sometimes it joins mixed flock report of a calling assemblage for the Collared (Restall et al. 2006) but is generally solitary. In Trogon. Unlike other reports, which indicate addition, the Collared Trogon is typically very that calling assemblages of trogons are mobile quiet, spending most of the time perched on and located in the canopy (Brosset 1983, branches in the subcanopy. The primary song Johnsgard 2000, Riehl 2008), the group of usually sounds like ‘cu cu cu cu.’ Very little is Collared Trogons reported here did not move known about its breeding biology, mating sys- and was located low in the subcanopy. Except tem, and courtship. Collared Trogons nest in for two short flights, the birds remained cavities, and both parents are involved in motionless during their calling. incubation and parental care (Skutch 1956). In some trogon species, both sexes partic- The breeding period is reported from January ipate in calling assemblages, possibly support- to May in Panama, Costa Rica and Colombia ing the view that they are strategically (Skutch 1956, Wetmore 1968, Hilty & Bronw important for delineating and reinforcing ter- 1986), from May to June in Venezuela (Scha- ritorial boundaries. Nevertheless, in most fer & Phelps 1954), and from October to Jan- cases only males participate, suggesting mate uary in Brazil (Johnsgard 2000). choice, or opportunities to extra-pair copula- tions as main functions (Riehl 2008). The OBSERVATIONS hypothesis that calling assemblages in trogons are similar to lek systems (Johnsgard 2000) is On 24 July 2014, in the Avila National Park, not based on any observational and experi- sector Sabas Nieves in Caracas, Venezuela, mental evidence. Trogons are monogamous, (1380 m a.s.l., 10°30’62’’N, 66°51’73’’W) at nest in cavities, and both sexes participate in 07:00 h, I observed a calling assemblage con- parental care, characteristics not correspond- sisting of five males of the Collared Trogon ing to lek-forming species, hence this hypoth- perched in different trees forming a semicir- esis seems unlikely. There is no evidence that cle at the edge of the footpath. They were sit- copulation occurs in the calling assemblage, ting ca. 3 m above the ground and separated as it has only been reported around the nest from each other about 2 m, with a maximum (Hall & Karubian 1996, Riehl 2008). On the separation of approximately 12 m. All males other hand, calling assemblages have been were calling simultaneously for about one only found during the brood period, suggest- hour before they left the site. The calls were ing that they are related to reproductive strikingly different from the primary song of behavior. Surhone et al. (2011) reported that 470 SHORT COMMUNICATIONS several females of the Narina Trogon were advantages of group foraging. Theor. Popul. attracted during a calling assemblage but no Biol. 30: 45–75. copulation occurred. In brief, the function of Collar, N. J. 2001. Family Trogonidae (Trogons). communal calling in trogons is yet uncertain. Pp. 80–129 in del Hoyo, J., A. Elliott, & J. Sarga- The callings reported here were not tal (eds). Handbook of the birds of the world. Volume 6: Mousebirds to hornbills. Lynx Edi- accompanied by tail displays as reported for cions, Barcelona, Spain. the courtship of the Elegant Trogon (Cully Cully, J. Jr. 1986. Mobbing behavior of a pair of 1986, Hall & Karubian 1996, Bitton & Elegant Trogons. Condor 88: 103–104. Doucet 2014). Calling assemblages are obvi- Eiserer, L. 1984. Communal roosting in birds. Bird ously rare in the Collared Trogon. Although it Behav. 5: 61–80. is a common bird in Venezuela, this behavior Foster, M. S. 1983. Disruption, dispersion, and has never been reported before. This is con- dominance in lek-breeding birds. Am. Nat. 122: cordant with my observations; although I 53–72. conducted nearly weekly bird surveys for six Griesser, M. 2008. Referential calls signal predator months in the study area and was able to behavior in a group-giving bird species. Curr. observe single trogons frequently, I only Biol. 18: 69–73. Haffer, J. 1975. Avifauna of northwestern Colom- observed grouping in this species once. bia, South America. Bonn. Zool. Monogr. 7: Nevertheless, with the exception of Riehl 1–182. (2008) there has been no systematic research Hall, L. S., & Karubian J. 1996. Breeding behavior on calling assemblages in trogons, but only of Elegant Trogons in southeastern Arizona. incidental reports (Wetmore & Swales 1937, Auk 113: 143–150. Haffer 1975, Zimmerman 1978, Brosset 1983, Hilty, S. L. 2003. A guide to the birds of Venezuela. Skutch 1983, Howell & Webb 1995, Johns- Princeton Univ. Press, Princeton, New Jersey, gard 2000, Riehl 2008). Further and more sys- USA. tematic studies could help to understand the Hilty, S. L., & W. L. Brown. 1986. A guide to the dynamics and ultimate causes of calling birds of Colombia. Princeton Univ. Press, assemblages in trogons. Princeton, New Jersey, USA. Howell, S. N. G., & S. Webb. 1995. A guide to the birds of Mexico and northern Central America. ACKNOWLEDGMENTS Oxford Univ. Press, New York, New York, USA. I want to thank Pedro A. Borges L., Carlos Hoglund, J. 2003. Lek-kin in birds – provoking the- Bosque, Jordan Karubian, and André Weller ory and surprising new results. Ann. Zool. for their suggestions on the manuscript, and Fenn. 40: 249–253. Adriana Rodríguez-Ferraro and Margarita Johnsgard, P. A. 2000. Trogons and quetzals of the Martínez for providing references. world. Smithsonian Institution Press, Washing- ton, D.C., USA. REFERENCES Kacelnik, A., & J. Krebs. 1982. 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