Life History of the Citreoline Trogon

Alexander F. Skutch
1948 The Condor  
In earlier papers I have given accounts of the nesting of the Mexican Trogon (Auk, 59, 1942:341-363) and the Quetzal (Condor, 46, 1944:213-235). I have not previously published anything on those members of the trogon family which carve the' ir nest chambers into termitaries, although the first trogons' nests that I found were in such situations. My earliest nest was one of the Massena Trogon (Trogon massenu) discovered in Honduras in 1930. The eggs in this were lost ; and in spite of much
more » ... spite of much searching I found no other trogons' nests until 1932, when three belonging to the Black-headed Citreoline Trogon (Trogon citreolus melanocephalus) were discovered on Alsacia Plantation, near Los Amates in the valley of the Rio Motagua in northeastern Guatemala. Here I had the good fortune' to follow all stages of the nesting activities, from the excavation of the chamber to the flight of the young. The Citreoline Trogons, of which several races have been distinguished, are distributed over a wide area extending from Sinaloa and southern Tamaulipas in MCxico to the Gulf of Nicoya in western Costa Rica. In general they prefer more or less arid country, such as prevails over the long stretch of the Pacific coast where they are at home, as well as in that part of their range which includes middle eastern MCxico, Yucatbn, and interior districts of northeastern Guatemala and northern Honduras. Near San Ger6nimo on the Pacific side of the Isthmus of Tehuantepec, I met Citreoline Trogons far from water amid the cacti and low, thorny scrub which cover so much of this dry and excessively hot region. In the vicinity of Matias Romero in the center of the Isthmus, I found them among the taller and more luxuriant trees along a river. Black-headed Citreoline Trogons are indeed resident in some of the rainiest regions of the Caribbean lowlands of Central America, although here they appear never to dwell in the heavy rain-forest itself, but prefer habitats where they receive more sunlight. In the humid lower Motagua Valley of Guatemala, and near Tela on the northern coast of Honduras, I found these trogons fairly common in pastures with scattered trees, in light secondgrowth woodland, along the edges of banana plantations, and among the fringes of trees bordering rivers flowing through the cleared districts. A heat-loving species, the Citreoline Trogon appears not to range far above sea level; but I am unable to define its upper altitudinal limit in Central America. Compared with such resplendent creatures as the Quetzal or even the Mexican and Massena trogons, the Citreoline Trogon is a bird of subdued plumage. When viewed perching well above the observer' s head, the male, appears to be clad largely in dull black, with rich orange-yellow on his belly, fading into yellowish-white where it adjoins the black or slate-color of his chest. One must see him resting low and in the sunshine to appreciate the full loveliness of the iridescent blue-green and golden-green plumage of his back and lesser wing coverts, and the metallic blue and violet-blue of his rump and upper tail coverts. His four middle rectrices are deep green with contrasting tips of black, the three outer pairs basally black with white terminal portions, the amount of white on these feathers varying greatly in the different races. The female is similar in 137 138 THE CONDOR Vol. 50 appearance but lacks most of the rich metallic coloration of the upper parts; yet except with favorable illumination it may be difficult to distinguish the sexes as one sees them among the trees (at least in the Black-headed Citreoline Trogon). In the race melanecephdus the whitish, pale yellowish or (according to Van Tyne, Univ. Mich. Mus. Zool. Misc. Publ., 27, 1935: 22) "Greenish Glaucous" bill of the male is, in some pairs at least, decidedly lighter than that of the female, and the ring of bare whitish skin surrounding each brown eye is more faintly tinged with blue--"Pale Russian Blue" according to Van Tyne. In the forms which inhabit the Pacific lowlands of Oaxaca and Chiapas, the iris is bright yellow and the naked orbital ring blue of so dark a shade that it does not contrast with the blackish feathers of the head and' in the field appears to be lacking. These differences in the color of eyes and eyelids, together with the more extensive white-on the outer tail feathers of the nominate race, are the best field characters for distinguishing it from melanocephdus, which until recently was considered to be a distinct species. A male of the black-headed race collected in El Peten by Van Tyne (lot. cit.) weighed 69.5 grams. FOOD Like other members of the family, Citreoline Trogons have a varied diet, consisting of both fruits and insects, which they pluck or catch while they hover momentarily on fluttering wings at the end of a long upward or outward dart. Among fruits, they are fond of the orange-colored pulp of that of the Central American rubber tree (Castillu), the green fruiting catkins of the guarumo (Cecropia) and berries of various sorts. Their animal prey includes dragonflies; mantises, grasshoppers and other orthopterans; big caterpillars, both hairy and hairless; and many smaller insects difficult to identify in their bills. Between their swift darts to seize food, the Citreoline Trogons rest motionless for protracted periods, perching very upright with their long tails directed almost vertically downward. Their Aight is distinctly undulatory. VOICE The usual call of the Citreoline Trogon is a low, throaty, unmelodious tuck tuck cucR tuck, easily distinguished from the clear, mellow, many-times-repeated COW COW cow, of the Gartered Trogon (Z' rogon violaceus) , another yellow-bellied species of open country with which it mingles over much of its range. During the mating season, which in the Caribbean lowlands of Guatemala is in April and May, several Citreoline Trogons of both sexes perch close together in the scattered trees that remain standing amid the cleared lands, calling at intervals in low, unimpassioned voices. As each calls, it jerks its tail up and down with rapid but mincing strokes and shakes its slightly relaxed wings. Occasionally one trogon darts at another, who usually retreats without any show of resistance. The birds are evidently courting, but the proceedings are so long drawn out that it requires extraordinary patience to follow them to their natural conclusion. Later, while carving out the nest cavity, the trogons give voice to low, whining notes which resemble the grunts of new-born puppies. NEST BUILDING After my incomplete experience with the nest of the Massena Trogons, I had expected to watch nesting trogons in the deep shadows of the forest; and no greater contrast can be imagined than that between my anticipations and the actuality of my second nest, my first of the Citreoline Trogbn. This was situated in a great black termitarium, atop a loti wooden post which supported a fence of barbed wire that separated a weedchoked cattle pen from a small marsh on Alsacia Plantation. Of all the trogons' nests T have seen, this had the least attractive site. The bulky termitary measured about two July, 1948 THE CITREOLINE TROGON 139 THE CONDOR Vol. 50 144 THE CONDOR Vol. 50
doi:10.2307/1364929 fatcat:lyadwvyqlvegng3vozcwxctbqa