Ornitología Neotropical (E-Journal)
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EFECTO DEL PASTOREO POR EL CAUQUÉN COMÚN (CHLOEPHAGA PICTA) EN CULTIVOS DE TRIGO (TRITICUM DURUM)
Get PDFRESUMEN ∙ Desde 1931 y hasta años recientes, el Cauquén Común (Chloephaga picta), Real (C. poliocephala) y Colorado (C. rubidiceps), fueron considerados plaga en Argentina, atribuyéndoles daños a la agricultura por consumo de pasturas y cereales, en particular trigo. Debido a esto fueron objeto de distintos métodos de control, lo que con‐ tribuyó a su reducción poblacional. El objetivo de este trabajo fue evaluar los efectos del pastoreo por el Cauquén Común en cultivos de trigo candeal (Triticum durum). El estudio se realizó en 2007 en la provincia de Buenos Aires, Argentina, principal zona de invernada de estas especies. Para cuantificar el efecto del pastoreo sobre el rinde, se dispusieron parcelas abiertas (pastoreadas) y clausuradas (sin pastoreo) de 2,25 m2 en dos potreros. Ambos potreros fueron pastoreados con una intensidad moderada a muy alta, sin embargo, no se observaron diferencias estadística‐ mente significativas en el rendimiento final de granos. El pastoreo tampoco produjo compactación del suelo, desarraigo o quemadura de plántulas. El período de interacción cauquenes‐cultivos es breve, alrededor de un mes y medio, y sus poblaciones y tamaños de bandadas reducidos. Si bien el alcance de este estudio está restringido en tiempo y espacio, y pese a la falta de replicación, la evidencia actual sugiere que el pastoreo por el Cauquén Común no afecta en forma negativa la producción de trigo candeal y es muy probable que no sea perjudicial como se creía previamente. ABSTRACT ∙ Effects of Upland Goose (Chloephaga picta) grazing on wheat (Triticum durum) crops In Argentina, from 1931 until recent years, the Upland Goose (Chloephaga picta), Ashy‐headed Goose (C. poliocephala), and Ruddy‐headed Goose (C. rubidiceps) were considered agricultural pests, mainly due to presumed damage by grazing on pastures and cereal crops, particularly wheat. This led to multiple measures of population control which have contributed to population declines. The aim of this study was to evaluate the effects of grazing by Upland Goose on wheat crops (Triticum durum). An exclusion experiment was conducted during 2007 in the province of Buenos Aires, Argentina, the main wintering area of the species. Experimental grazed and non‐grazed plots of 2,25m2 were set up in two wheat fields to quantify the effects of Upland Goose grazing on yield. Both fields were grazed at moderate to high intensity, but we found no statistical differences in wheat productivity between treatments. Grazing did not lead to soil compaction, uprooting, or burning of seedlings and we found no damage on crops as assumed. The geese-crop interaction period is short, about one and a half months, and geese numbers are low. Although the scope of this study was restricted in time and space, and further replication is desirable, current evidence suggests that Upland Goose grazing has no detrimental effects on wheat production
DIVERSIDAD Y COMPOSICIÓN DE ESPECIES DE AVES EN UN GRADIENTE BOSQUE-ARBUSTAL-SABANA DEL CHACO SEMIÁRIDO, ARGENTINA
Get PDFRESUMENEl paisaje primitivo predominante de la región chaqueña de Argentina, Paraguay, Bolivia y Brasil fue un mosaico de bosques alternando con pastizales y sabanas. Regionalmente el sobrepastoreo produjo el reemplazo de las comunidades herbáceas de pastizales y sabanas por comunidades de leñosas, dando origen a amplios arbustales. El objetivo de este trabajo fue evaluar la variación de la diversidad y composición de aves en un gradiente de tres tipos de hábitats del Chaco Semiárido: (i) Bosque de Quebrachos (Aspidosperma quebracho‐blanco, Schinopsis lorentzii); (ii) Arbustal bajo, una versión degradada de la; (iii) Sabana de Aibe (Elionurus muticus). Los resultados sugieren que la diversidad de aves fue determinada por la complejidad vertical de la vegetación y el grado de similitud de los ensambles de aves por el grado de similitud entre los tipos de hábitats. Ello produjo: (i) un decrecimiento gradual de la diversidad de aves desde el hábitat más complejo (Bosque) al menos complejo (Sabana); (ii) una composición única de especies en el Bosque y la Sabana (los hábitats más disimiles), donde las especies afines a hábitats cerrados prevalecen en el primero y las afines a hábitats abiertos prevalecen en el segundo y; (iii) que el Arbustal bajo, con mayor similitud al Bosque que a la Sabana, represente un hábitat poco favorable para las aves afines a hábitats abiertos. En áreas boscosas el manejo debe orientarse a mantener o mejorar la estructura vegetal. En arbustales, pastizales y sabanas el uso del fuego prescripto puede beneficiar a las aves afines a hábitats abiertos.ABSTRACT ∙ Diversity and composition of bird assemblages in a forest‐shrub‐savanna gradient of the Semiarid Chaco, ArgentinaThe primitive landscape predominant in the Chaco region of Argentina, Paraguay, Bolivia and Brazil, was a patchwork of forests alternating with grasslands and savannas. Regionally, over‐grazing produced the replacement of herbaceous communities of grasslands and savannas for woody communities, leading to widespread shrublands. The aim of this study was to evaluate variation in diversity and composition of birds in a gradient of three types of habitats of Semiarid Chaco: (i) Quebrachos Forest (Aspidosperma quebracho‐blanco, Schinopsis lorentzii); (ii) Low shrubland, which constitutes a degraded version of the; (iii) Aibe Savanna (Elionurus muticus). The results suggest that the diversity of birds was determined by the vertical complexity of the vegetation and the degree of similarity of bird assemblages by the degree of similarity between habitat types. This led to: (i) gradual decreases in diversity of birds from the more complex (Forest) to the less complex habitat (Savanna); (ii) a unique composition of species in the Forest and the Savanna (more dissimilar habitats), where birds of closed habitats prevail in the first and open habitat species in the second and; (iii) Low shrubland, displaying greater similarity to the Forest than to the Savanna, representing a habitat unsuitable for open habitat birds. In forested areas the management should strive to maintain or improve the vegetal structure. In shrublands, grasslands and savannas prescribed fire could be used to favor open habitats birds
ASSESSMENT OF STOMACH CONTENTS OF SOME AMAZONIAN BIRDS
Get PDFStudies on avian diet provide important information about biology and ecological relationships of species, for instance, predation and competition. Despite the importance, studies about trophic ecology in the Neotropical region are still scarce, especially in the Amazonian region. The Brazilian Amazon hosts a high diversity of birds, with about 1300 resident species. However, trophic ecology of the regional avifauna is still poorly studied. This paper aims to describe the composition of the diet of some Amazonian bird species. Bird specimens were collected in the Aripuanã municipality, northern Mato Grosso state, Brazil. The analysis of the stomach contents of the collected birds was the method used to assess diets of birds. We analysed the stomach contents of 59 birds of 40 species. A total of 573 food items were identified and could be assigned to 16 different classes. Hymenoptera was the most abundant class. Hymenoptera and Coleoptera classes were the most frequent. Our results provide information on the diet of endemic Amazonian species, of which there is a lack of information in the literature. These facts are therefore important for future studies on the biology and ecology of these birds
USE OF PHYLOGENETIC ANALYSIS TO IDENTIFY EVOLUTIONARILY SIGNIFICANT UNITS FOR THE ORANGE-FRONTED PARAKEET (EUPSITTULA CANICULARIS) IN MEXICO
Get PDFIn avian conservation biology, the subspecies concept based on reciprocal monophyly has been successfully applied to define priority populations through Evolutionarily Significant Units (ESUs). In México, the Orange-fronted Parakeet (Eupsittula canicularis) ranks first in illegal parrot trade. Its distribution ranges from southern Sonora to Chiapas on the Pacific slope, with populations representing three subspecies: E. c. canicularis, E. c. eburnirostrum, and E. c. clarae. To identify and propose ESUs to assist in conservation proposals for different populations, we assessed subspecific reciprocal monophyly via phylogenetic analyses and haplotype networks based on the mitochondrial DNA genes cytochrome oxidase I y NADH dehydrogenase 2. Feather and blood samples from specimens collected from nests in 2005 and 2007 were used. A total of five specimens of E. c. eburnirostrum from two localities in the state of Michoacán and four specimens of E. c. clarae from the state of Sinaloa were analyzed and no specimens of E. c. canicularis were included. The analyses included sequences obtained by us and those previously reported for E. aurea, E. cactorum, E. canicularis, E. nana, and E. pertinax. Both the phylogenetic analyses and haplotype networks suggest two groups that correspond to two subspecies of E. canicularis based on morphological and geographical evidence. Therefore these two subspecies are proposed as independent ESUs for conservation purposes
CALYX-WATER CONSUMPTION BY BLUE-AND-YELLOW MACAWS IN SPATHODEA CAMPANULATA (BIGNONIACEAE) FLORAL BUDS
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CAMBIOS TEMPORALES EN LA DIETA DEL PLAYERO ROJIZO (CALIDRIS CANUTUS RUFA) EN UN HUMEDAL DE PENÍNSULA VALDÉS, PATAGONIA ARGENTINA
Get PDFTemporal variation in the diet of the Red Knot (Calidris canutus rufa) in a wetland from Península Valdés, Patagonia Argentina. – During their northward migration, Red Knots forage extensively in intertidal areas of Península Valdés (Patagonia, Argentina). This species has a small population and declines have been linked to reduced prey availability in migratory stopover sites. Thus, knowing the temporal variation in prey availability and diet is essential to understand population dynamics in the Red Knot. We studied temporal variation in the diet of the Red Knot at Colombo Beach (northeastern Nuevo Gulf, Península Valdés). To evaluate prey availability, we sampled benthic invertebrates in March every study year. We collected 292 feces during April in 2002, 2003, 2006, and 2007. Prey items were identified by using key hard structures. The clam Darina solenoides was the most common prey positively selected every year (Savage index), although in some years the polychaete Travisia olens was also selected. Other, less important prey items were seeds, mussels, insects, crustaceans, isopods, amphipods, ostracods, the snail Buccinanops globulosus, and the clam Tellina petitiana. Red Knots selected clams in variable size ranges depending on the year (10–18 mm in 2002, 8–22 mm in 2003, 10–20 in 2006, and 18–26 mm in 2007 mm). In the years where the contribution to biomass by the clam D. solenoids was lower, knots had a higher trophic diversity. Diet composition varied between years mainly due to differences in the intake of polychaetes
UNUSUAL NEST AND NESTLING APPROPRIATION BY THE EARED DOVE (ZENAIDA AURICULATA)
Get PDFAbstract ∙ We report a case of interspecific nest appropriation by the Eared Dove (Zenaida auriculata) on a nest of the Creamy‐bellied Thrush (Turdus amaurochalinus). The usurpation attempt resulted in the death of both nestlings, including a parasitic cowbird, despite forceful attempts by the thrushes to retake their nest and repeated attempts by the dove to feed the nestlings. We believe that the loss of the dove offspring from a nest in a neighboring tree could have triggered this behavior, which may be a hormonal byproduct caused by the recent loss of their own offspring, similar to what has been observed in Emperor Penguins (Aptenodytes fosteri).Resumen ∙ Inusual apropiación de nido y pichones por parte de la Paloma Torcaza (Zenaida auriculata) Reportamos un caso de apropiación interespecífica de nido en donde una Torcaza (Zenaida auriculata) usurpa el nido de un Zorzal Chalchalero (Turdus amaurochalinus). Ambos pichones, incluido un pichón parásito de cría, resultaron muertos tras la usurpación, a pesar de los enérgicos esfuerzos de los zorzales por recuperar el nido y de los repetidos intentos de la paloma para alimentar los pichones. Creemos que la Torcaza perdió sus propios pichones cerca del nido de zorzal y esto motivó la usurpación. Atribuimos el falso reconocimiento de los pichones a un subproducto hormonal causado por la pérdida de sus propios pichones, similar a lo observado en el Pingüino Emperador (Aptenodytes fosteri)
GENETICS AND DEMOGRAPHY OF KELP GULLS IN PATAGONIA
Get PDFThe Kelp Gull (Larus dominicanus), a common seabird in coastal Patagonia, has recently increased in overall abundance and distribution, creating some concerns for the protection and conservation of other native, threatened species. We combined genetic and demographic data of four large Kelp Gull colonies distributed along 1800 km of the northern Patagonian coast of Argentina to further understand patterns of population growth and migration of the species. DNA analysis of variable intron sequences of two separate genes (myelin proteolipid protein, β-fibrinogen) revealed similar intra-colony levels of DNA sequence diversity. Pairwise FST comparisons revealed significant differentiation of the northernmost colony, Islote La Pastosa, from the two southern colonies, Punta Tombo and Isla Vernaci Sudoeste (p < 0.05). Indirect estimates of gene flow suggest significant mixing among colonies (Nm > 6). Demographic estimates revealed that Islote La Pastosa showed an increase in the number of breeding individuals over time (λ = 1.075), representing an area of potential population expansion. This is consistent with previous studies that have suggested that the demographic connectivity among Kelp Gull colonies in Patagonia may follow a source-sink dynamics, where growth rates of growing colonies are fuelled by the immigration of individuals from nearby colonies. The observed pattern also reflects the overall expansion of the species in the Patagonian region. This study suggests that proper management strategies for the Kelp Gull should take into account the genetic and demographic dynamics of this species
NESTING OF THE SCRUB TANAGER (TANGARA VITRIOLINA) IN ANDEAN ECUADOR
Get PDFThe Scrub Tanager (Tangara vitriolina) occurs in dry inter-Andean valleys of Colombia and northern Ecuador. Even though it thrives in human-made habitats, knowledge about its breeding biology is scarce, with no complete description of its nest. In this paper, I present a detailed description of its nest, eggs, and nestlings, including notes on its breeding behavior. The nest is an open cup constructed with grass fibers, dry sticks, rootlets, plastic fibers, dry leaf litter and other vegetal material, spider web, and mammal hair. It was built near the tip of a hanging vine, supported below by three intertwined twigs, 2 m above ground. The female incubated whitish blue eggs speckled brown for 14–15 days. The male attended closely and brought food to the female several times. Nestlings were fed mostly by the female. The nesting pair did not attempt a second brood at this nest after failure; instead, they collected nesting material from this nest up to three days after nest failure
OBSERVACIONES DE EVENTOS DE DISPERSIÓN DEL PATO DE LOS TORRENTES (MERGANETTA ARMATA)
Get PDFResumen ∙ El Pato de los Torrentes (Merganetta armata) es un ave especialista de ríos de aguas rápidas que se distribuye por la cordillera de los Andes desde el sur de Argentina y Chile hasta Venezuela. Aquí aportamos nueva información sobre eventos de dispersión a través de un registro casual y seguimiento de ejemplares anillados en Argentina. Nuestras observaciones sugieren eventos de dispersión crepusculares y nocturnos, un juvenil fue registrado volando de noche sobre tierra firme, a 300 metros del cuerpo de agua más cercano. Las distancias de dispersión fueron en general bajas (2–9 km). Sin embargo, un macho anillado se desplazó entre 22 y 84 km de distancia, dependiendo de si la ruta empleada fue volando sobre tierra firme o realizada siguiendo cursos de agua, respectivamente. Es necesario estudiar la capacidad dispersiva de esta especie para determinar el potencial de aislamiento genético entre poblaciones y probables barreras geográficas.Abstract ∙ Observations on dispersal events of Torrent Ducks (Merganetta armata) The Torrent Duck (Merganetta armata) is a white‐water river specialist distributed along the Andes from southern Argentina and Chile to Venezuela. Here we provide new information on dispersal based on ringed individuals and occasional records from Argentina. Our observations suggest nocturnal or crepuscular dispersal events, a juvenile was recorded flying at night on land, 300 m away from the nearest shore. Dispersal distances were in general low (2–9 km). However, one ringed male dispersed between 22 and 84 km, depending on whether it flew over land or followed watercourses, respectively. It is necessary to study the dispersal ability of this species to determine the potential for genetic isolation between different populations and likely geographical barriers