Colonial Breeding of the Eared Dove (Zenaida auriculata) in Northeastern Brazil
1982; Wiley; Volume: 14; Issue: 4 Linguagem: Inglês
10.2307/2388083
ISSN1744-7429
Autores Tópico(s)Ecology and Vegetation Dynamics Studies
ResumoEared doves (Zenaida auriculata) migrate into the semi-arid Brazilian northeast toward the end of the wet season; there they breed in huge colonies of millions of birds and then disperse. Colonial breeding is clearly restricted to the thornscrub formation known as and only occurs during the four-month period following the end of the rainy season. During their stay in the area, the doves depend primarily on Croton spp. seeds which are abundant but are an extremely clumped and unpredictable resource due to the extreme irregularity of the rainfall. Colonies are markedly short-lived and well-synchronized; the adults stay for about 60 days-long enough to complete only one successful breeding. Although the wooded vegetation would clearly permit nesting in trees, nests are built only on the ground; this practice is interpreted as an adaptation for speed in breeding. I suggest that eared doves might perform a sort of itinerant breeding, in which individuals attempt to nest again in a different locality where a favorable seed production has occurred, following the geographical movement of the wet season. Because of the dependence of the eared dove populations on Croton productivity patterns, it is suggested that the management policy aimed toward conservation of the species should not rely solely on protection of the breeding colonies but should also take into account the complex interrelationship among climatic irregularity, land use, and Croton seeds productivity. RESUMEN La paloma Avoante o Pomba do bando (Zenaida auriculata) migra cada aiio al nordeste arido del Brasil, donde se reproduce en enormes colonias en las que se concentran millones de individuos, y dispersandose posteriormente. Estas colonias de cria estan claramente restringidas a la formacion vegetal arbustiva y espinosa conocida como Caatinga; y solamente ocurren durante un periodo de cuatro meses posterior al inicio de la epoca de las Iluvias. Durante su permanencia en el area las palomas se alimentan fundamentalmente de semillas de Croton spp., las que constituyen un recurso abundante pero de distribucion irregular e impredecible debido a la extrema variabilidad de las Iluvias. Las colonias son de muy corta duracion y muestran un alto grado de sincroni'a en el proceso de nidificacion. Las adultos permanecen alrededor de unos 60 dias, tiempo suficiente para completar una sola postura. Aunque la vegetacion arbustiva claramente permite la ubicacion de los nidos sobre los arboles estos son construidos 'unicamente en el suelo, lo que es interpretado como una adaptacion tendiente a abreviar el periodo de nidificacion. Sugiero que esta paloma podria Ilevar a cabo en la region una especie de cria itinerante, por la cual cada individuo realizaria sucesivcys intentos de cri'a en diferentes localidades favorecidas por una adecuada produccion de semillas, a lo largo de la onda de Iluvias que atraviesa la region. Debido a que la paloma zenaida auriculata depende en gran medida de los patrones de produccion de semillas de Croton, se seiiala que cualquier politica de manejo tendiente a la conservacion de esta especie en la debe estar basada no solamente en la proteccion de las colonias de cria sino que ademas tiene que considerar la compleja interrelacion existente entre irregularidad cilmatica, uso de la tierra, y productividad de semillas de Croton. IN A MANNER REMINISCENT OF THE EXTINCT PASSENGER PIGEON (Ectopistes migratorius) of North America and the flock pigeon (Phaps histrionica) of the Australian desert, enormous numbers of the eared dove (Zenaida auriculata) migrate at the end of the wet season (March-June) into the semiarid Caatinga region of northeastern Brazil to form temporary breeding colonies, performing what has been considered by Sick (1968) as the strongest migration yet known among native birds in South America. In spite of its spectacular nature, published literature on the subject is scarce (Ihering 1935, Aguirre 1976). Although the tendency toward gregariousness and nomadic movements seems to be widespread within the species', range throughout South America, the development of huge, temporary breeding colonies associated with seasonal movements is a distinctive behavioral feature of the populations. No such combination appears to have been found elsewhere; the only partly comparable situation is the recent establishment of more or less permanent colonies in central Argentina following agricultural development of the land (Murton et al. 1974). In this paper I intend not only to integrate the available published information and my own observations on the natural history of the eared dove in the Caatinga, but also to point out facts that may be useful in understanding the adaptive value of colonial breeding in doves. It is the result of detailed observations made at an active eared dove breeding colony near Campos Sales, Ceara (fig. IA) during April and May 1976. I also visited the areas where colonies have been reported in the Brazilian states of Ceara, Piaui, Rio Grande do Norte, and Pernambuco. GEOGRAPHICAL CONTEXT In northeast Brazil, colonial breeding of the eared dove is restricted to an area known locally as Caatinga (fig. IA). It is a very well-defined natural BIOTROPICA 14(4): 255-261 1982 255 This content downloaded from 157.55.39.51 on Wed, 10 Aug 2016 05:13:50 UTC All use subject to http://about.jstor.org/terms C tSk=~~~~~~~~~~~~~~~~~~~~~~~_T8 146
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