Composición de la dieta de Halcones Peregrinos (Falco peregrinus cassini) depredando en una colonia mixta de aves marinas en la Patagonia Argentina

Predation is one of the main factors determining breeding strategies in many seabird species (Lack 1968, Burger & Gochfeld 1994, Gaston 2004). Among avian predators, raptors such as eagles, owls and falcons regularly prey on seabird adults and offspring (Paine et al. 1990, Holt 1994, Hayward et al. 2010). The Peregrine Falcon (Falco peregrinus) has a cosmopolitan distribution (White et al. 2002), and is regularly found along coastal areas of Argentine Patagonia which are characterized by large seabird breeding assemblages (Yorio et al. 1999). Peregrine Falcons from coastal populations in the Northern Hemisphere have been shown to be important predators of seabirds (Ratcliffe 1980, Paine et al. 1990, Velarde 1993), but very little is known on the contribution of seabird prey to Peregrine Falcon diet in coastal Argentina. Few studies have quantified their diet in Patagonia, and they indicate that prey composition may vary depending on location (Ellis et al. 2002, Santillán et al. 2010). Our goal was to determine the prey composition and contribution of seabirds to the diet of a pair of Peregrine Falcons breeding near a mixed-species seabird colony on the coast of Argentine Patagonia.Fil: García, Germán Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Bó, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Yorio, Pablo Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Reproductive behavior of White-tailed Kites (Elanus leucurus) in the Pampas of Argentina

The White-tailed Kite (Elanus leucurus) is a raptor that has been less studied in the Neotropics than in the Nearctic region, especially in relation to its reproductive behavior. In this study, we report information about the phenology and activity patterns of this raptor at the Pampas of Argentina. We found that White-tailed Kites have a prolonged breeding season, from October to May. Time-activity budgets of mating pairs indicated a pronounced division of roles in parental care between sexes. Females devoted most of their time to nest construction, incubation and chick care (80% of total time) and males to food provisioning and vigilance (70% of total time). We registered 11 cases of prey transfer from the male to the female. In four cases the transfer occurred in flight and in the remaining seven cases while individuals were perched. Our results agree with general patterns on breeding behavior of White-tailed Kites from North America, suggesting a consistent behavioral pattern throughout the species´ distribution.Fil: Baladrón, Alejandro Victor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Cavalli, Matilde. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Pretelli, Matías Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Bó, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin

Activity Budgets, Foraging Behavior, and Diet of White-Tailed Kites (Elanus leucurus) during Breeding and Nonbreeding Seasons in the Argentine Pampas

From 2005 to 2009 we evaluated the activity patterns and food habits of White-tailed Kites (Elanus leucurus) during the breeding and nonbreeding seasons in the Argentine Pampas. According to time-activity budget analyses, perching was the most frequently observed activity during the nonbreeding season (52% of total time), whereas foraging was the most frequent activity during the breeding season (41% of total time). Flight was the least frequent of all kites' activities in both seasons (8% and 9% during the breeding and nonbreeding season, respectively). Even when kites spent a similar percentage of time foraging during both breeding and nonbreeding seasons (41% and 39%, respectively), their hunting technique differed between seasons. During the nonbreeding season, we only observed kites using active searching to forage, but during the breeding season, we observed them using active and passive searching in similar proportions. According to pellet analyses, the diet of kites was mostly composed of rodents (> 96% of total prey). Small rodents (body mass < 35 g) were dominant in numeric terms in the diet in both seasons, but larger rodents represented the bulk of biomass. Our results indicate that in the Argentine Pampas, White-tailed Kites are predominantly mammal-eating, active-search predators, as previously reported for the species in South America and North America and for other Elanus species around the world.Fil: Baladrón, Alejandro V.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Pretelli, Matías Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Cavalli, Matilde. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Bó, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin

Burrowing owls eavesdrop on southern lapwing's alarm calls to enhance their antipredatory behaviour

Eavesdropping is a widespread behaviour among animals, providing the receiver with valuable information to assess the habitat, resources or threats. This kind of behaviour has been reported for the burrowing owl (Athene cunicularia), which in its northern range lives in close association with fossorial mammals and eavesdrops on their alarm calls as indicators of risk. In their southernmost range, burrowing owls do not associate with mammals, but they are often found sharing foraging and nesting patches with the southern lapwing (Vanellus chilensis), a noisy, territorial and aggressive plover species. We designed a field experimental study aimed at determining if burrowing owls are able to use lapwing calls as indicator of potential risk. We exposed focal owls to a sequence of sounds including lapwing alarm calls, and biological and non-biological controls, and registered their response as alert or relax behaviours. Linear mixed modeling showed that owls increased their alert behaviour in response to lapwing alarm calls but not in response to control treatments. In addition, owls’ response was consistent between habitats (rural and urban) and seasons (breeding and non-breeding). Our results suggest that eavesdropping is a generalized strategy of burrowing owls to acquire environmental information throughout its distribution range.Fil: Cavalli, Matilde. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Baladron Felix, Alejandro Victor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Isacch, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Bó, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin

Leukocyte profiles and body condition of free-living Burrowing owls (Athene cunicularia) from rural and urban areas

Species living in urban areas are exposed to novel and potentially stressful human perturbations. In response to the increasing number of stressors in these habitats, animals may manifest changes in their immune system, body condition and physiology. Many bird species are negatively impacted by urbanization, but other species survive and thrive in urban areas. The capacity to adjust the stress responses to the conditions of urban areas may play a key role to explain the success of bird species in this habitat. In this study, we compared indicators of stress and body condition in free-living Burrowing owls (Athene cunicularia) inhabiting urban and rural areas. We calculated a scaled index of body condition, assessed leukocyte profiles and calculated the heterophil/lymphocyte (H/L) ratios of chicks and adult Burrowing owl individuals. We found that the total white blood cell counts, the relative leukocyte count, and the H/L ratio were similar in owls from rural and urban areas, as well as their body condition. Chicks showed higher counts of white blood cells relative to adult owls, which may be associated with developmental stages and immune system activation processes. Here we provide the first Burrowing owl baseline data of leukocyte profile, one that can be used as a reference when developing future studies.Fil: Cavalli, Matilde. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Baladron Felix, Alejandro Victor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Isacch, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: D'amico, Veronica Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Nacional Patagónico; ArgentinaFil: Bó, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin

Chimango Caracara (Milvago chimango) entangled in fishing tackle in southeastern Buenos Aires province, Argentina

Chimango (Milvago chimango) enredado en aparejos de pesca en el sudeste de la provincia de Buenos Aires, Argentina Las artes y aparejos de pesca abandonados, perdidos o descartados, incluidas las líneas de nylon o monofilamento, a menudo tienen un impacto negativo en una variedad de aves. Sin embargo, es escasa la información disponible para aves rapaces en América del Sur. Presentamos tres casos de aves enredadas o mutiladas en el sudeste bonaerense, Argentina; todos pertenecientes al Chimango (Milvago chimango). Los avistamientos incluyen una hembra mutilada (2015) y un macho y dos hembras enredadas en líneas de nylon o monofilamento (2017). Todos los hallazgos incluyeron individuos vivos durante la temporada reproductiva de la especie.Abandoned, lost, or discarded fishing tackle, including monofilament lines, often result in negative impacts on a variety of birds. However, scarce information is available for South American raptors. Here we report three instances of raptor entanglements or injured birds in southeastern Buenos Aires, Argentina, all belonging to the Chimango Caracara (Milvago chimango). The sightings include one injured female (2015), and one male and two females entangles in nylon monofilament lines (2017). All observations referred to live individuals during the species breeding season.Fil: Seco Pon, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Bó, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Block, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Galván, Federico Emilio. Mar del Plata; ArgentinaFil: García, Germán Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin

Comparison of the diet of two bird-eating raptors, the Aplomado Falcon (Falco femoralis) and the Cinereous Harrier (Circus cinereus), in the Pampean Region of Argentina

We studied the diet and hunting activity of two bird-eating raptors, the Aplomado Falcon (Falco femoralis) and the Cinereous Harrier (Circus cinereus), in Mar Chiquita Biosphere Reserve, Argentina. Prey was identified by analyzing pellets collected during December 2005. The Cinereous Harrier showed a higher consumption of birds than the Aplomado Falcon (92,3% vs 67,9% of total prey, respectively), and a reverse tendency was observed for the biomass contribution (26% vs 88%). In addition, these raptors showed differences in hunting techniques: the Aplomado Falcon used a sit-and-wait strategy, whereas the Cinereous Harrier used an active-search strategy. Our results suggest that both factors, the use of different prey and hunting modes, could be important for trophic niche segregation between these two bird-eating raptors.Fil: Baladrón, Alejandro V.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Bó, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Cavalli, Matilde. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Martinez, Guadalupe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin

Breeding phenology and nest survival of cinereous (circus cinereus) and long-winged (c. buffoni) harriers in the agricultural landscapes of north-east Patagonia, Argentina

We present novel data on breeding ecology and nest survival of the Cinereous (Circus cinereus) and Long-winged (C. buffoni) Harriers in modified grasslands of southern Argentina and we evaluate variations in daily nest survival rates (DSR) in relation to temporal and habitat variables. We studied three mixed nesting colonies embedded in agricultural landscapes along a road. We found that DSR decreased linearly with time of breeding and increased with vegetation height above the nest and the distance to the road. This is the first and most complete reproductive study concerning two species of conservation concern, namely the Cinereous and Long-winged Harriers in Patagonia. Our study provides valuable and novel insights into the population dynamics of these little-known species.Fil: Segura, Luciano Noel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología de Vertebrados. Sección Ornitología; ArgentinaFil: Bó, Maria Susana. Universidad Nacional de Mar del Plata; Argentin

Annual diet of the Striped Owl (Asio clamator) in the southernmost boundary of its distribution

El Lechuzón Orejudo (Asio clamator) es una rapaz nocturna que habita ambientes abiertos y arbolados de la región Neotropical. Esta especie ha sido caracterizada como un depredador especializado en la captura de aves y mamíferos en diferentes áreas de su distribución, aunque la mayor parte de los trabajos se basan en registros locales de corto plazo de las presas consumidas. En este trabajo, estudiamos la dieta de A. clamator a lo largo de un año en el sudeste de la región pampeana de Argentina, que corresponde al límite austral de la distribución de la especie. Para esto analizamos 126 egagrópilas recolectadas entre febrero de 2005 y marzo de 2006 en un bosque de tala (Celtis tala). Calculamos las frecuencias numéricas y en biomasa de cada ítem presa y la amplitud de nicho trófico, y comparamos la dieta entre periodos (reproductivo y no reproductivo) mediante el Coeficiente de Concordancia de Kendall. La dieta de A. clamator estuvo dominada por mamíferos tanto en número (78,5% del total de presas) como en biomasa (93,1% de la biomasa total), seguidos en importancia por las aves (21,5% del total de presas). Entre los mamíferos se destacaron los roedores, y en particular Rattus spp., mientras que entre las aves se destacó Myiopsitta monachus, constituyendo el primer reporte de consumo de psitácidos para esta rapaz. La amplitud de nicho trófico para el periodo completo mostró valores medios a bajos. No registramos diferencias en la composición de la dieta entre los diferentes periodos. Nuestros resultados indican que, en el límite más austral de su distribución, A. clamator se comporta como un depredador especializado en vertebrados a lo largo de todo el año, y concuerdan con lo reportado para otras áreas en cuanto a la importancia de las presas grandes (> 100 g) en la dieta de esta especie.The Striped Owl (Asio clamator) is a nocturnal raptor that inhabits open and forested habitats of the Neotropical region. This species has been characterized as a specialized predator of birds and mammals in different areas of its distribution range, although most studies are based on local, short‐term records of prey consumed. In this study, we investigated the diet of A. clamator along the year in the southeast of the Pampas region of Argentina, which corresponds to the southernmost boundary of the species distribution range. We analyzed 126 pellets collected between February 2005 and March 2006 in a forest of Celtis tala. We calculated numeric and biomass frequencies of each prey item and the food‐niche breadth, and compared diet composition among periods (breeding and non‐breeding) using Kendall's Coefficient of Concordance. The diet of A. clamator was dominated by mammals in terms of numeric (78.5% of total prey) and biomass frequencies (93.1% of total biomass), followed in order of importance by birds (21.5% of total prey). Rodents were the most important prey among mammals, particularly Rattus spp., whereas among birds the most important prey was Myiopsitta monachus, representing the first record of consumption of parrots by this raptor. Food‐niche breadth showed moderate to low values for the whole period. We did not detect differences in diet composition between the different periods. Our results indicate that, at the southernmost boundary of its distribution range, A. clamator behaves as a specialized predator of vertebrates throughout the year, in agreement with reports from other areas regarding the importance of big‐sized prey (> 100 g) in the diet of this species.Fil: Baladron Felix, Alejandro Victor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; ArgentinaFil: Bó, Maria Susana. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentin

Parental care and behavior of breeding American Kestrels (Falco sparverius) in central Argentina

We studied reproductive parameters, agonistic interactions, foraging behavior, prey deliveries, and diet of American Kestrels (Falco sparverius) using nest boxes in semiarid forests in central Argentina. The breeding season (from egg-laying to fledging) began in late October and ended in late December. Average clutch size was 4.3 ± 0.3 (SE) eggs (N 6 nests), hatching success was 73%, and nest success was 66%. Incubation was primarily by females, whereas males mostly hunted and defended the nest area. During early and late nestling stages, both sexes showed aggressive behavior against intruders. The primary hunting method we observed kestrels using near the nest box was perch-hunting (99), with a peak in hunting activity during midday for females and during morning for males. Both sexes visited the nest most frequently during the late nestling stage (males: 1.04 ± 0.47 prey/hr; females: 1.22 ± 0.35 prey/hr), likely because of high energy demands of the nestlings for growth during that time. The majority of the nestling diet was arthropods (71.4% of diet as determined by observations; 71% by pellets; 89% by prey remains). Reproductive characteristics of this species in the semiarid forest of central Argentina, including reproductive rate, role partitioning between sexes, foraging behavior, and diet, are similar to those previously recorded for some populations in North America.Fil: Liébana, María Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Mar del Plata. Facultad de Cs.exactas y Naturales. Departamento de Biología. Laboratorio de Vertebrados; ArgentinaFil: Sarasola, José Hernán. Universidad Nacional de La Pampa. Facultad de Ciencia Exactas y Naturales. Departamento de Recursos Naturales. Centro para el Estudio y Conservación de Aves Rapaces; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; ArgentinaFil: Bó, Maria Susana. Universidad Nacional de Mar del Plata. Facultad de Cs.exactas y Naturales. Departamento de Biología. Laboratorio de Vertebrados; Argentin