Departamento de Ecologœa, Instituto de Biologfa, UNAM, Apartado Postal 70-233, Coyoacdn 04510, D.F., Mgxico The Trogonidae are important frugivores in the tropics, especially in the American tropical forests (Snow 1981). However, with the exception of quet- zals (Skutch 1944, Wheelwright 1983) and some data on the diet of the Orange-bellied Trogon (Trogon au- rantiiventris; Wheelwright et al. 1984), their feeding ecology is poorly known. In the tropical deciduous forest of the Mexican west coastß the Citreoline Tro- gon (Trogon citreolus citreolus) is one of the most abun- dant resident members of the frugivore guild. To our knowledge there are no reports on its foraging be- havior or on the fruit species that it eats. We report here on the fruits eaten by the Citreoline Trogon and on its foraging behavior, during the dry season from 6 to 26 April 1984. The observations were made in the tropical decid- uous and subdeciduous forest in hilly areas and in the riparian vegetation of dry arroyo beds located near the Estaci6n de Biologia Tropical de Chamela (Jalisco, Mxico, 19ø30'N, 105ø03'W, 0-250 m eleva- tion). For a description of the location and vegetation see Solis (1980). Intensive observations were made at a fruiting fig tree (Ficus pertusa) on 13 and 16 April. On these dates, data were collected on the frequency of arrivals at the tree, foraging rates, and time spent  Present address: Department of Zoology, Univer- sity of Florida, Gainesville, Florida 32611 USA. on each fruit. Timing was done to the nearest 0.2 s with two stopwatches. Ripe fruits of all species eaten by the trogons were measured and weighed, with the exception of Comocladia engleriana (Anacardiaceae), the resinous exudates of which cause severe irritation of the skin. Trogons regurgitated Recchia mexicana seeds after removing the pulp; we estimated the weight of the consumed pulp and skin of the fruit by subtract- ing the weight of the seed from the weight of the whole fruit. Four fruit species were used by the Citreoline Tro- gon during the observation period (Table 1). Two were drupes produced by small trees (Recchia mexi- cana and Comocladia engleriana), one was the berry of a vine (Trichostigma octandrum), and one was the sy- conium of a fig tree (Ficus pertusa); the latter two plants were from riparian habitats. The fruiting seasons of these plants (except F. pertusa) are restricted to the end of the dry season (February-May; Table 1). Fruit- ing fig trees were scarce in the study area; in an in- tensive survey only one F. pertusa with ripe fruits was found. Trichostigma octandrum berries were locally abundant in large areas of the arroyo beds. Fruiting trees of R. mexicana and C. engleriana were common but widely dispersed, and each tree had few ripe fruits (100-400 in R. mexicana, 30-600 in C. engleriana) rel- ative to the thousands of fruits of T. octandrum and F. pertusa. The weights and characteristics of the fruits of each species are summarized in Table 1. TABLE I. Fruit eaten by the Citreoline Trogon during the dry season at Chamela, Jalisco, Mexico. Values are means + SD. Size (mm) Species Length Width Weight (g) n Fruiting season a Ficus pertusa (Moraceae) Trichostigma octandrum (Phytolacacea) Comocladia engleriana (Anacardiaceae) Recchia mexicana (Simaroubacea) 14.5 + 1.1 12.3 + 2.0 0.94 + 0.19 30 Allyear 8.1 + I.! 8.1 + I.! 0.18 + 0.05 25 March-May 10.0 + 1.2 14.2 + 1.3 7 February-April 12.4 + 0.3 11.7 + 0.4 0.83 + 0.1 30 March-May (0.23 + 0.03) b Data from the Herbario Nacional (MEXU) at the Instituto de Biologla. Weight of fruit without seed. The trogons picked fruit from all species in a sim- ilar way. Birds searched for and chose fruits while perched on branches in or near the fruiting tree. The behavior of perching trogons indicated that perching time was used, at least in part, to search for fruit, as the birds turned their heads while peering toward fruit clusters. In the fig tree the time spent per fruit was esti- mated from a regression of the time spent feeding (Y) and the number of fruits eaten during this period (X): Y = -82 + 91.8X (r = 0.88, n = 27). The slope of the regression is the time invested per fruit (Table 2). This value refers to the time spent flying to get the fruit, to handle and swallow it, and to search for a new fruit; it does not include the time required for digestion. Figs were crushed in the bill before they were swallowed (Table 2). Mean chewing times, mean distance of flight for a fig, and mean duration of each flight were estimated directly (Table 2). The average time spent sitting between flying bouts, estimated from the slope value and the flying and handling times, was 79.2 s. Fruits of the other three species were swallowed whole. The larger seeds of R. mexicana and C. engler- iana were regurgitated; it was common to see the tro- gons gaping in the regurgitation process. Trogons fed throughout the day (0630-1830). Visits to R. mexicana and C. engleriana were rare and usually were performed by solitary individuals; in contrast, TABLE 2. Citreoline Trogon feeding at Ficus pertusa. Values are means + SD unless otherwise indicated. Time invested/fig (s) Duration of flight/fig (s) Time spent chewing 1 fig (s) Time spent sitting between flying bouts (s) Distance of flight/fig (m) Number of birds arriving/5 rain 91.0 + 15.6 a 1.6 + 0.6  10.8 + 4.2 79.2 2.5 + 1.5 c 3.9 + 4.1 a SE. 40, range = 0.6-3.8 s. 42, range = 0.5-8.0 m. 84 5-min intervals. the fig tree and clumps of T. octandrum berries were visited intensively. The distribution of the number of arrivals to the fig tree per 5 rain (Table 2) was significantly dumped (variance/mean = 4.24, t = 20.87, P < 0.01; Smith 1980), suggesting that the tro- gons were foraging in loose flocks. A similar behav- ior has been reported for quetzals feeding in heavily fruiting trees (Wheelwright 1983). As in other trogons, insects probably comprise a substantial proportion of the diet, especially for nest- lings and in times of fruit scarcity (Bent 1940, Skutch 1944, and data from gut contents of specimens of the bird collection at the Instituto de Biologla), but we saw only two individuals feeding on insects during TABLE 3. Birds observed feeding from the fruits of the plants used by the Citreoline Trogon. FP = Ficus pertusa, TO = Trichostigma octandrum, CE = Comocladia engleriana, RM = Recchia mexicana. X in- dicates presence at the plant. Species FP TO CE RM Wagler's Chachalaca ( Ortalis poliocephala) Orange-fronted Parakeet (Aratinga canicularis) Lilac-crowned Parrot (Amazona finschi) Citreoline Trogon (Trogon citreolus) Golden-cheeked Woodpecker (Melanerpes chrysogenys) Social Flycatcher (Myiozetetes similis) Great Kiskadee (Pitangus sulphuratus) Yellow Grosbeak (Pheucticus chrysopeplus) Grayish Saltator (Saltator coerulescens) Yellow-winged Cacique ( Cacicus melanicterus) Streak-backed Oriole (Icterus pustulatus)  S. Bullock pers. comm. the 20 days of observation. These birds hovered be- low the undersides of leaves and snatched the in- sects. Trogons were never seen perched near the ground (perching range 3-15 m) and never perched close to another trogon (minimum distance between individ- uals, 50 cm). Intraspecific aggressions were seen only twice and involved male-female interactions [tro- gons apparently breed later in the year (June-July; data from specimens of the bird collection at the In- stituto de Biologia)]. No interspecific aggressions in- volving a Citreoline Trogon were recorded. The fruits used by the Citreoline Trogon in the study area were used by other bird species (Table 3). The Grayish Saltator (Saltator coerulescens) commonly used all species of fruits. The Yellow-winged Cacique (Cacicus melanicterus) was common at F. pertusa and T. octandrum and occasional at R. mexicana, but was ab- sent at C. engleriana. In R. mexicana the caciques were wasteful feeders, stripping the fleshy part of the fruits without swallowing the seed and dropping many half-eaten fruits to the ground below the parent tree. Wagler's Chachalaca (Ortalis poliocephala) consumes figs and fruits of C. englen'ana and R. mexicana (S. Bul- lock pers. comm.), but we did not observe the species feeding from F. pertusa or from C. engleriana; chacha- laca activity in R. mexicana was confined to the early morning and dusk. We are very thankful for the facilities provided by the Instituto de Biologia at the Chamela field station. Arturo Solis and Emily Lot helped to identify the plants, and Steve Bullock gave wise advice and valu- able information. Rodolfo Dirzo, Daniel Pifiero, Val- eria Souza, Francisco Molina, Jorge Sober6n, and Al- berto Burquez read and commented on a previous manuscript. The comments and suggestions of Eu- gene Mortonß John O'Neill, and Nathaniel Wheel- wright greatly improved the paper. We are grateful to them all. LITERATURE CITED BENT, A. C. 1940. Life histories of North American cuckoos, goatsuckers, hummingbirds and their allies, part 1. U.S. Natl. Mus. Bull. 176. SKUTCH, A. F. 1944. Life history of the Quetzal. Condor 46: 213-235. SMITH, R. L. 1980. Ecology and field biology. New York, Harper and Row. SNOW, D. W. 1981. Tropical frugivores and their food plants: a world survey. Biotropica 13: 1-14. SOLIS, A. 1980. Las leguminosas de Chamela, Jalisco. Unpublished B.Sc. thesis, Facultad de Ciencias, Univ. Nacional Autonoma de Mexico. WHEELWRIGHTß N.T. 1983. Fruits and the ecology of Resplendent Quetzals. Auk 100: 286-301. ß W. A. HABER, K. G. MURRAY, & C. GUINDON. 1984. Tropical fruit eating birds and their food plants: a survey of a Costa Rican lower montane forest. Biotropica 16: 173-192. Received 9 July 1984, accepted 4 April 1985.