The Dwarf Cuckoo in Venezuela

Abstract

The Dwarf Cuckoo (Coccyzus pumilus) is a poorly known species; the only detailed observations of its breeding biology were made near Cali, Colombia by Ralph (Condor 77:60-72, 1975). Meyer de Schauensee (The species of birds of South America with their distribution, Livingston Publishing Co., Narberth, Pa., 1966) reported it as found in parts of Colombia and Venezuela in tropical and occasionally subtropical zones. Phelps and Phelps (Lista de las aves de Venezuela con su distribucion, Tomo 2, Parte 1, Bol. Soc. Venez. Ciencias Nat., 19, No. 90, 1958) described it as very locally distributed in Venezuela. I made the following observations on Fundo Pecuario Masaguaral, a cattle ranch in the state of Gu~irico, central Venezuela. This ranch is in the Venezuelan Ilanos, an extensive low-altitude grassland with scattered trees and occasional gallery forests. The habitat is designated as dry tropical woods by Ewel and Madriz (Zonas de vida de Venezuela, Ministerio de Agricultura y Cria, Republica de Venezuela, 1968). The llanos have a highly seasonal hydrology; rains from May through October flood the ground in places to a depth of over 50 cm; the other six months of the year are extremely dry. On the morning of 19 July 1973, I observed a Dwarf Cuckoo perched in some dense thorny bushes surrounding the base of an isolated palm tree in an area where the seasonal water was more than 30 cm deep. While preening, the cuckoo occasionally uttered a five to six note rattling churr. This call resembles a portion of the vocal duet of the White-bearded Flycatcher (Myiozetetes inornata), a permanent resident of the area. Another cuckoo answered briefly from the far side of the bushes. Ralph interpreted this call as a pair contact. The preening bird made another sound at about 11-sec intervals, a low single click which was accompanied each time by a shake of its body. Probably this is the same vocalization characterized by Ralph as cluck or tok. Later I found a nest in the same bushes, but on the side facing an open marsh. It was placed in a horizontal crotch of thorny branches at a height of 2 m. The nest was about 18 cm in diameter and constructed of small sticks so loosely put together that sky could be seen through it. A young cuckoo crouched on the supporting branch beside the nest. The juvenile cuckoo had a pale gray head and nape, and light brown back, wings and tail. Below, it was dirty white, entirely lacking the orange rufous throat and upper breast of the adult. The eye ring, which is red in the adult, was dull yellow. When the young bird heard the low clicks of an adult it became excited, gaped, then flew or glided down into the foliage. An adult cuckoo guarded the nest area, sometimes with vigor. A Smooth-billed Ani (Crotophaga ani) flew into the bushes and was immediately attacked and driven away. At another time a Gray-capped Cuckoo (Coccyzus lansbergi) landed in the bushes, but it left in haste after only a few seconds. On the other hand, a pair of preening Scaled Doves (Scardafella squammata) was tolerated in the nest bush and a pair of Pied Water-Tyrants (Fluvicola pica) nesting 4 m away was unmolested. About half an hour after I found the juvenile, an adult cuckoo, which proved to be male, flew into the bush with a large moth in his bill. The moth was buff-colored with a thick furry body about 3 cm long. The cuckoo called and was answered, then a second adult cuckoo met it on a small horizontal branch. The pair perched side by side and engaged in an active tug-of-war, each alternately pulling the moth. The male jerked the moth free and then both birds flew to a higher perch. While the moth struggled, the male cuckoo mounted the female, who grasped the insect's body as they copulated. When they separated, the male was still holding the moth, but the female pulled it away from him and tried to eat it. The moth freed itself and dropped down into thick foliage where the female cuckoo followed