A case of partial leucism in the American Barn Owl (Tyto furcata) (Temminck, 1827), from Buenos Aires province, Argentina

The diverse colorations of a birds’ plumage are due to either structural colors or pigments that are synthesized in specialized cells or incorporated through the diet. However, plumage color aberrations can occur; several cases of albinism and leucism have been reported for different bird species and some examples correspond to Strigiformes. A specimen of the American barn owl (Tyto furcata) with partial leucism was found in Carhué, Buenos Aires province. The plumage of its facial disc, tail and the ventral region was completely white; furthermore, the neck, and the primary and secondary remiges were pigmented although in a significantly lighter fashion than in normal-phenotype specimens. The rest of the body presented a normal pattern for the species.Fil: Chiale, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico Zoología Vertebrados; ArgentinaFil: Pagano Luis Gerardo. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico Zoología Vertebrados; Argentina. Grupo Falco; Argentin

A case of partial leucism in the American Barn Owl (Tyto furcata) (Temminck, 1827), from Buenos Aires province, Argentina

The diverse colorations of a birds’ plumage are due to either structural colors or pigments that are synthesized in specialized cells or incorporated through the diet. However, plumage color aberrations can occur; several cases of albinism and leucism have been reported for different bird species and some examples correspond to Strigiformes. A specimen of the American barn owl (Tyto furcata) with partial leucism was found in Carhué, Buenos Aires province. The plumage of its facial disc, tail and the ventral region was completely white; furthermore, the neck, and the primary and secondary remiges were pigmented although in a significantly lighter fashion than in normal-phenotype specimens. The rest of the body presented a normal pattern for the species.Facultad de Ciencias Naturales y Muse

A case of partial leucism in the American Barn Owl (Tyto furcata) (Temminck, 1827), from Buenos Aires province, Argentina

The diverse colorations of a birds’ plumage are due to either structural colors or pigments that are synthesized in specialized cells or incorporated through the diet. However, plumage color aberrations can occur; several cases of albinism and leucism have been reported for different bird species and some examples correspond to Strigiformes. A specimen of the American barn owl (Tyto furcata) with partial leucism was found in Carhué, Buenos Aires province. The plumage of its facial disc, tail and the ventral region was completely white; furthermore, the neck, and the primary and secondary remiges were pigmented although in a significantly lighter fashion than in normal-phenotype specimens. The rest of the body presented a normal pattern for the species.Facultad de Ciencias Naturales y Muse

A case of partial leucism in the American Barn Owl (Tyto furcata) (Temminck, 1827), from Buenos Aires province, Argentina

The diverse colorations of a birds’ plumage are due to either structural colors or pigments that are synthesized in specialized cells or incorporated through the diet. However, plumage color aberrations can occur; several cases of albinism and leucism have been reported for different bird species and some examples correspond to Strigiformes. A specimen of the American barn owl (Tyto furcata) with partial leucism was found in Carhué, Buenos Aires province. The plumage of its facial disc, tail and the ventral region was completely white; furthermore, the neck, and the primary and secondary remiges were pigmented although in a significantly lighter fashion than in normal-phenotype specimens. The rest of the body presented a normal pattern for the species.Facultad de Ciencias Naturales y Muse

Primera descripción del nido y pichones del Milano de Corbata (Harpagus diodon) en Argentina

Damos a conocer el primer registro de nidificación y la descripción de los pichones del Milano de Corbata para Argentina. El 19 de enero de 2008 hallamos un nido del Milano de Corbata en el PP Salto Encantado, Misiones. El árbol nido, una grapia (Apuleia leiocarpa) de unos 30 m de altura. Observamos dos pichones totalmente emplumados con las rectrices a medio desarrollar, consideramos que la edad de los pichones era de 24-28 días.Fil: Jordan, Emilio Ariel. Grupo Falco; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pagano, Luis. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico Zoología Vertebrados; Argentina. Grupo Falco; ArgentinaFil: Roesler, Carlos Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina. Grupo Falco; Argentin

Aguilucho alas anchas (Buteo platypterus) en las serranías de Tartagal, Salta, Argentina : registros novedosos

Fil: Pagano, Luis Gerardo. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología Vertebrados; ArgentinaFil: Grilli, Pablo Gervasio. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología Vertebrados; ArgentinaFil: Marateo, Germán. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología Vertebrados; Argentin

Aportes sobre Atajacaminos (Caprimulgidae) en la provincia de Salta, Argentina

La publicación de numerosos artículos y trabajos relacionados a caprimúlgidos que mencionan novedades acerca de su nidifcación (Krauczuk 2000, 2013, Pautasso & Cazenave 2002, Bodrati & Baigorria 2013, Salvador & Bodrati 2013, Salvador et al. 2014, Schaaf et al. 2015), alimentación (Bodrati & Cockle 2012, Bodrati & Salvador 2015), depredación (Fariña et al. 2014), hábitos (Mazar Barnett et al. 1998, Bodrati & Cockle 2012, Salvador & Bodrati 2013), nuevas localidades (Jaramillo 2000, Imberti 2001, Bodrati 2004, Bodrati & Klavins 2004, Marateo et al. 2009, Bodrati & Cockle 2012, Krauczuk 2013) e incluso especies nuevas para el país (Krauczuk 2000, Bodrati & Areta 2010), demuestra que aun falta mucho por conocer sobre este grupo en la Argentina. Aportamos información obtenida durante noviembre de 2011 sobre nuevas localidades, nidificación y dieta de tres especies de caprimúlgidos en la provincia de Salta, Argentina.Fil: Pagano, Luis G.. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico Zoología Vertebrados; ArgentinaFil: Barneche, Jorge Adrian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - la Plata. Centro de Estudios Parasitologicos y de Vectores. Universidad Nacional de la Plata. Facultad de Cs.naturales y Museo. Centro de Estudios Parasitologicos y de Vectores; ArgentinaFil: Jensen, Roberto Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Limnología "Dr. Raúl A. Ringuelet". Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Limnología; Argentin

Bifurcation analysis of a DC–DC bidirectional power converter operating with constant power loads

Direct current (DC) microgrids (MGs) are an emergent option to satisfy new demands for power quality and integration of renewable resources in electrical distribution systems. This work addresses the large-signal stability analysis of a DC–DC bidirectional converter (DBC) connected to a storage device in an islanding MG. This converter is responsible for controlling the balance of power (load demand and generation) under constant power loads (CPLs). In order to control the DC bus voltage through a DBC, we propose a robust sliding mode control (SMC) based on a washout filter. Dynamical systems techniques are exploited to assess the quality of this switching control strategy. In this sense, a bifurcation analysis is performed to study the nonlinear stability of a reduced model of this system. The appearance of different bifurcations when load parameters and control gains are changed is studied in detail. In the specific case of Teixeira Singularity (TS) bifurcation, some experimental results are provided, confirming the mathematical predictions. Both a deeper insight in the dynamic behavior of the controlled system and valuable design criteria are obtained.Postprint (updated version

VOCALIZACIONES, SONIDOS MECÁNICOS Y DESPLIEGUES DEL ATAJACAMINOS ALA NEGRA (ELEOTHREPTUS ANOMALUS) EN ARGENTINA

Resumen ∙ El Atajacaminos Ala Negra (Eleothreptus anomalus) habita pastizales húmedos del Sur de Sudamérica y se lo considera “cercano a la amenaza” debido a su baja abundancia y pérdida de hábitat. El macho se caracteriza por alas extrañas, con forma de hacha, con las primarias curvadas hacia atrás y las secundarias sensiblemente más cortas, posiblemente una adaptación para producir sonidos mecánicos. Se especula que su sistema de apareamiento podría ser tipo lek, pero existe poca evidencia, no se han descripto sus despliegues y existe confusión sobre el origen y significado de sus sonidos. Aquí presentamos información sobre los sonidos y despliegues de E. anomalus en base a grabaciones y observaciones realizadas con una población marcada en Reserva Natural Rincón de Santa María, Corrientes, Argentina (RNRSM; 2009–2018) y observaciones adicionales en Barra Concepción, Misiones, Argentina (2003–2004). En los últimos 9 años observamos concentraciones de hasta 15 machos realizando despliegues en dos tramos de caminos elevados y poco transitados de la RNRSM, que consideramos arenas de despliegue, reforzando la idea de que se trata de un sistema lek. Encontramos cinco tipos de sonidos. 1) Hembras y machos realizan llamadas de contacto (series de "tik" o "tzk"; dos variaciones). 2) Machos realizan voces durante el comportamiento de exhibición en arenas de despliegue ("Trrrrrrrrrrr"; seis variaciones). 3) Machos posados en el suelo o en vuelo emiten trinos de baja frecuencia ("priIUpririririri"; tres variaciones). 4) Una hembra realizó una voz de llamada muy suave ("guaá-ku…”), posiblemente para contactarse con pichones. 5) Machos realizan sonidos mecánicos con las alas en las arenas de despliegue ("tuk" o "brrrt"; cuatro variaciones). Frente al avance humano sobre los pastizales del cono sur, es importante utilizar el conocimiento de estos sonidos para investigar otros aspectos de la historia natural como su biología reproductiva, distribución actual, movimientos estacionales, y efectos de fuego y otros disturbios en su hábitat y poblaciones.Abstract ∙ Vocalizations, mechanical sounds, and displays of the Sickle-winged Nightjar (Eleothreptus anomalus) in Argentina The Sickle-winged Nightjar (Eleothreptus anomalus) inhabits humid grasslands in southern South America and is considered “near threatened” because of its low abundance and habitat loss. The male is characterized by peculiar wings, shaped like an axe, with the primaries curved inward and the secondaries noticeably shorter, possibly an adaptation for producing mechanical sounds. It is speculated that its mating system is lek-like, with little evidence at present; its displays have not been described, and there is confusion about the origin and significance of its sounds. Here we contribute information about the sounds and displays of E. anomalus based on recordings and observations of a marked population at Reserva Natural Rincón de Santa María, Corrientes, Argentina (RNRSM; 2009–2018) and additional observations at Barra Concepción, Misiones, Argentina (2003–2004). In the last 9 years, we observed concentrations of up to 15 males displaying on two sections of elevated, little-used road in the RNRSM, which we consider display arenas, reinforcing the idea of a lek-mating system. We found five types of sounds. 1) Females and males make contact calls (series of "tik" o "tzk"; two variations). 2) Males vocalize during exhibition flights at display arenas ("Trrrrrrrrrrr"; six variations). 3) Males on the ground or in flight emit low-frequency trills ("priIUpririririri"; three variations). 4) A female emitted a very soft call ("guaá-ku…”), possibly to contact chicks. 5) Males make mechanical sounds with their wings at display arenas ("tuk" or "brrrt"; four variations). Considering how humans are advancing into the grasslands of the southern cone, it is important to use the knowledge of these sounds to investigate other aspects of natural history, such as reproductive biology, current distribution, seasonal movements, and effects of fire and other disturbance on habitat and populations

NOTAS SOBRE LA BIOLOGÍA REPRODUCTIVA Y EL CICLO ANUAL DEL ATAJACAMINOS ALA NEGRA (ELEOTHREPTUS ANOMALUS) EN ARGENTINA

Resumen ∙ El Atajacaminos Ala Negra (Eleothreptus anomalus) es una especie amenazada cuya biología reproductiva es casi desconocida. En la Reserva Natural Rincón de Santa María (Corrientes, Argentina) capturamos adultos entre 2012 y 2019. Realizamos 47 capturas de hembras y 209 de machos, de los cuales 13 hembras y ningún macho tenían parche incubatorio. La temporada reproductiva comenzó en agosto con marcada actividad sonora (mecánica y vocal) por parte de los machos en reuniones de tipo leks. Adultos en estado reproductivo se encontraron entre octubre y enero cuando aún capturamos hembras con parches incubatorios y juveniles dependientes. Colocamos radiotransmisores a dos hembras con parche incubatorio. Una hembra con radiotransmisor hizo dos posturas con una diferencia de 12 días y 361 m de distancia entre sí, pero ambas fueron depredadas. Las posturas fueron de uno y dos huevos aunque es posible que la primera puesta haya sido depredada antes de completarse. Los huevos eran de color blanco cremoso con manchas y pintas marrones rojizas y manchas y placas grises de variable tamaño, en toda la superficie. La densidad y distribución de las marcas variaba entre los huevos, incluso en una misma nidada. Las medidas y pesos de los huevos fueron 27,3 x 21,9 mm, 7,2 g; 26,6 x 20,8 mm, 6,2 g; y 25,8 x 21,1 mm, 6,3 g. Los huevos fueron puestos directamente sobre (1) pasto seco aplastado, rodeado de pastizal nativo de 2,2 m de alto con algunas matas de Baccharis dracunculifolia y (2) en tierra desnuda arriba de un tacurú (nido viejo de hormiga carpintera, Camponotus sp.) de unos 50 cm de alto, rodeado de pastizal nativo inundado. Es importante confirmar el cuidado uniparental en Eleothreptus anomalus y poner a prueba la hipótesis de un sistema de apareamiento tipo lek como se ha propuesto para su único congénere el Atajacaminos Ala Blanca (Eleothreptus candicans).Abstract ∙ Notes on reproductive biology and annual cycle of the Sickle-winged Nightjar (Eleothreptus anomalus) in Argentina The Sickle-winged Nightjar (Eleothreptus anomalus) is a threatened species whose reproductive biology is almost unknown. At Reserva Natural Rincón de Santa María (Corrientes, Argentina), we captured adults between 2012 and 2019. We made 47 captures of females and 209 of males, of which 13 females and no males had brood patches. The reproductive period began in August with marked production of sounds (mechanical and vocal) by males in lek-like groupings. Adults in reproductive condition were found between October and January when we still captured females with brood patches and dependent juveniles. We attached radio transmitters to two females with brood patches. One radio-tagged female laid two clutches with a difference of 12 days and separated by 361 m, but both were depredated. The clutches contained one and two eggs, respectively, although it is possible that the first clutch was depredated before it was completed. The eggs were creamy white with reddish-brown patches and spots, and grey patches of variable size, all over the surface. The density and distribution of markings varied among eggs, even within the same clutch. Egg measurements and weights were 27.3 x 21.9 mm, 7.2 g; 26.6 x 20.8 mm, 6.2 g; and 25.8 x 21.1 mm, 6.3 g. Eggs were laid directly on (1) crushed dry grass, surrounded by native grassland, c. 2.2 m tall, with some Baccharis dracunculifolia shrubs and (2) on bare earth atop an old nest of Camponotus sp. ants, about 50 cm high, surrounded by flooded native grassland. It is important to confirm uniparental care in the Sickle-winged Nightjar and test the hypothesis of a lek-mating system as proposed for its only congener, the White-winged Nightjar (Eleothreptus candicans)