Showing papers by "University of Córdoba (Spain) published in 1974"

The Ecology of the Eared Dove (Zenaida Auriculata) in Argentina

Abstract: In South America, south of Trinidad and other islands in the southern Caribbean, the familiar Mourning Dove (Zenaida macroura) of North America is replaced by the Eared Dove (Zenaida auriculata) also known as "Torcaza," "Mediana," or "Paloma dorada;" three distinctive but intergrading races have been described. The Eared Dove is very similar to the Mourning Dove in color and pattern but differs primarily in having a shorter, less graduated tail, heavier bill, more brownish coloration, and more distinctly yellow-bronze display plumage on the neck; these two doves comprise a super-species. There are numerous published references to the Mourning Dove but very little has been recorded about the biology of its southern congener. Comparative studies of closely related species are of interest for they often reveal features not readily seen in isolation. The Eared Dove also poses an economic problem for it has prospered with the development of intensive arable farming and thrives on corn and sorghum crops, the latter eaten from the standing crop from November until March. In addition, some farmers have almost stopped growing millet because the birds take the ripe crop. This is true of wheat also, but to a lesser extent. In its relationship with agriculture, the Eared Dove can be compared with certain Old World pigeons, particularly the Wood Pigeon ( Columba palumbus), while its capacity to form enormous flocks for breeding and feeding is reminiscent of the extinct Passenger Pigeon (Ectopistes migratorius) of the eastern United States and the Red-billed Dioch (Quelea quelea) an African weaver finch. The natural habitat of Z. auriculata is mostly arid and semiarid scrubland, usually with some trees or patches of woodland, but it avoids the tropical forest areas. Its niche is similar to that occupied by the collared doves of the Old World [the Vinaceous Dove (Streptopelia vinacea), the Mourning Dove (S. decipiens), and the Pink-headed Dove (S. roseogrisea) of Africa; the Collard Dove (S. decaocto) of India and since 1930 of northwest Europe and Britain; and the Turtle Dove (S. bitorquata) of Java]. All these doves are ground feeders that eat small weed seeds. In South America Z. auriculata was found in th thornscrub Chaco region of Argentina and Para uay, which originally was a mosaic of woodland and grassland maintained as a stable, climax community by periodic fires (Odum 1969; Morello 1970). Although very common in this favored pulsatile ecosystem, the species never formed the enormous flocks w ich are still typical of the more xeric caat nga region of Brazil (fig. 1). There the enormous flocks of Eared Doves are nomadic, ranging over very large areas in search of the seeds of wild grass and other plants, in a mann r reminiscent of the Flock Pigeon (Phaps histrionica) of the Australian desert and the African Weaver Finch. Sandwiched between the coastal and Amazonian rain forests is a corridor of savannas known as the Cerrado, which extends from the Chaco to the Caatinga, t roughout which the Eared Dove is common (fig. 1). In Argentina, the Pampas region was, until the end of the 19th century, covered with native grasslands with practically no trees. The Eared Dove was a common, albeit not characteristic, bird of the region for many migrated in large flocks from the Chaco to feed on thistle seeds which were abundant