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t In tropical and subtropical forest ecosystems, cavities formed by decay processes are a key but scarce resource for birds that nest and roost in them, which makes them a highly sensitive group to logging. The piedmont forest of northwestern Argentina is a complex ecosystem with 113 tree and 120 bird species. It has high logging pressure on the few, well-conserved forest remnants, complicating the delineation of sustainable management guidelines for each tree or bird species in a short time. Our objective was to reduce the complexity of subtropical forests by grouping tree species according to the characteristics used by secondary cavity-nesting birds (i.e. non excavators). In the piedmont forest, 50 plots of 0.25 ha were sampled to record cavity trees and cavity characteristics. These were then used in a cluster analysis to form tree groups. Additionally, cavities were searched to identify the bird species using the decay-formed cavities. A total of 187 cavity trees, comprising 23 tree species, were recorded, and these formed four tree groups or clusters. We recorded 86 cavities that were used by secondary cavitynesting bird species. The four tree groups were unequally used by secondary cavity nesters. The tree group that included valuable timber species (Myroxylon peruiferum, Anadenanthera colubrina and Calycophyllum multiflorum) and had the greatest cavity availability represented 71% of total cavity use. Another tree group with valuable timber species (Cedrela balansae and Amburana cearensis), measured [ 73 cm DBH and [21 m tall, had cavity entrances [0.10 cm2 , and contributed 14% of all cavity use by birds. A third group had no highly economically valuable tree species, and included the snag category (i.e. standing dead trees) as well as a 15% of cavity use. The fourth tree group had a DBH \ 0.40 cm, only one highly economically valuable tree species (Cordia trichotoma), and supported no cavity use. The clustering of subtropical trees can reduce the complexity of these forests, hence easing their management by focusing on those groups with tree species showing similar characteristics and providing suitable nesting sites for secondary cavity-nesting birds. Fil: Schaaf, Alejandro Alberto. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina. Fundación Cebio; Argentina Fil: Ruggera, Román Alberto. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina. Fundación Cebio; Argentina Fil: Tallei, Ever Denis. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina. Fundación Cebio; Argentina Fil: Vivanco, Constanza Guadalupe. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina. Fundación Cebio; Argentina Fil: Rivera, Luis Osvaldo. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina. Fundación Cebio; Argentina Fil: Politi, Natalia. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina. Fundación Cebio; Argentina

Studies dealing with the selection of tree species and characteristics for cavity-nesting birds are important to evaluate the abundance and quality of available resources in the environment. The aim of this study is to characterize the use of trees by woodpecker species in the subtropical piedmont forests of northwestern Argentina by using the analysis of niche selection, breadth and overlap in a total of five woodpecker species of different body size found in these subtropical forests: White-barred Piculet Picumnus cirratus (small woodpeckers), Golden-olive Woodpecker Colaptes rubiginosus, Golden-green Woodpecker Piculus chrysochloros, Dot-fronted Woodpecker Veniliornis frontalis (medium- sized woodpeckers), and Cream-backed Woodpecker Campephilus leucopogon (largest woodpeckers). From a total of 54 tree species, only 15 were used by these woodpecker species. Primary excavator species were moderate specialists in tree use (Levin's index), and they showed selection according to their availability (Ivlev's index) of four of the fifteen tree species (Calycophyllum multiflorum, Amburana cearensis, Cedrela balansae, Astronium urundeuva) and snags. There was a high overlap (Morisita's overlap index) in the use of tree species between Picumnus cirratus and medium-sized woodpeckers, while less overlap was found between Campephilus leucopogon and other woodpecker species. Both living trees and snags were used by the woodpeckers, although snags were more important for small and medium-sized woodpeckers, whereas living trees were more important for Campephilus leucopogon. Both snags and living trees had a large diameter at breast height (DBH) in > 50 cm. Results show the existence of different cavity-excavation niches for woodpecker species in subtropical forests of Argentina, and they allow us to identify the important relationships between these birds and the available tree species. Thus, the results of this work may be useful to develop sustainable forest management guidelines for this group of birds. Fil: Schaaf, Alejandro Alberto. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Ruggera, Román Alberto. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Vivanco, Constanza Guadalupe. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Tallei, Ever Denis. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Benavídez, Analía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Catamarca. Universidad Nacional de Catamarca. Centro de Investigaciones y Transferencia de Catamarca; Argentina. Universidad Nacional de Jujuy. Facultad de Ciencias Agrarias. Centro de Estudios Ambientales Territoriales y Sociales; Argentina Fil: Albanesi, Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Biodiversidad Neotropical. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Biodiversidad Neotropical. Instituto de Biodiversidad Neotropical; Argentina Fil: Rivera, Luis Osvaldo. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Politi, Natalia. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Desde su captura hasta el destino final, los loros silvestres experimentan diferentes condiciones durante el transporte, originando así oportunidades de infección y transmisión de enfermedades. Conocer la prevalencia de parásitos en loros habladores silvestres (Amazona aestiva) permitirá un control más eficiente de las parasitosis en aquellos individuos destinados al cautiverio. Además, este trabajo ayudará a determinar qué parásitos son específicos del loro hablador, y cuales son los resultados de infecciones desde otras especies hospedadoras durante el proceso de comercialización. El objetivo de este estudio fue describir los parásitos gastrointestinales de los loros habladores en la región del Impenetrable Chaqueño, en Argentina. Fueron colectadas muestras de heces de 38 pichones y cuatro adultos. También se examinaron cuatro pichones muertos. Un tercio de los nidos inspeccionados (n=21) y un cuarto de los individuos examinados fueron positivos a la presencia de protozoos y helmintos. A nivel individual, Eimeria sp fue el parasito más prevalente (25%), seguido de Isospora sp (5%), Giardia lamblia (5%), Capillaria sp (2%) y Ascaridia sp (2%). Las inspecciones en busca de parásitos en las vísceras de los cuatro pichones hallados muertos por causas naturales, fueron negativas. Como en la mayoría de los estudios con loros silvestres, la prevalencia de parásitos intestinales en el loro hablador fue baja, si se compara con los valores reportados para loros en cautiverio. Debido a que los pichones de este loro son capturados frecuentemente para el tráfico de mascotas, conocer el ensamble de parásitos intestinales y su prevalencia en individuos silvestres, puede ser útil para el tratamiento de pichones destinados al cautiverio. From capture to final destination, wild parrots experience several conditions during transport which enhance/promote chances of infections and transmission of diseases. A better understanding of the prevalence of parasites in wild blue-fronted amazons (Amazona aestiva) will allow a more efficient control of the parasitosis in those individuals destined to captivity. Furthermore, it will be helpful in determining which parasites are specific to the blue-fronted amazons and which are the result of infections from other host species during the commercialization process. The objective of this study was to establish the baseline of gastrointestinal parasites of wild blue-fronted amazons in the Chaco region. We collected fecal samples of 38 nestlings and 4 adults, andexamined four dead nestlings. One-third of examined nests (n=21) and one quarter of the individuals examined were positive for protozoa and helminths. At the individual level, Eimeria sp was the most prevalent (25%), followed by Isospora sp (5%), Giarda lamblia (5%), Capillaria sp (2%) and Ascaridia sp (2%). The tests for parasites in theviscera of the four nestlings found dead from natural causes were negative. As in most wild studies, the prevalence of intestinal parasites in blue-fronted amazons was low, when compared to the parasitic infection levels reported for parrots in captivity. Because the nestlings of this parrot are frequently captured for pet trade, knowledge of theassemblage and prevalence of intestinal parasites of the species in wild individuals can be useful for the treatment of nestlings destined for captivity. Fil: Berkunsky, Igor. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto Multidisciplinario de Ecosistemas y Desarrollo Sustentable; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Ruggera, Román Alberto. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina Fil: López, M. S.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; Argentina Fil: Faegre, S. I.. University of Washington; Estados Unidos Fil: Aramburu, Rosana Mariel. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Área Zoología; Argentina

Fruit pulp is an important source of nutrients for many bird species. Fruit-eating birds use a variety of strategies to cope with changes in the availability of fruits, exhibiting a remarkable ability to track resources. We assessed the role of nutrient availability in the fruiting environment as a factor driving resource tracking by fruit-eating birds. Fruit consumptionby the four most common frugivorous species in a 6-ha plot in the Southern Yungas montane forest of Argentina was assessed. We determined the content of selected nutrients (soluble carbohydrates, proteins, phenols, ascorbic acid and essential minerals) in 22 fruiting plant species eaten by birds, and measured fruit-frugivore interactions and the availability of nutrients and dry fruit pulp mass over 2 years. There was strong temporal covariation in the availability of the selected nutrients in fruits across the study period. Similarly, the availability of nutrients in the fruiting environment co-varied with pulp mass. Fruit consumption by the four commonest bird species and theabundance of most species were positively associated with nutrient availability and dry pulp mass. Nutrient availability was a good predictor of temporal fruit tracking by three of the four commonest frugivores. Despite large differences in particular nutrient concentrations in fruits, overall nutrient (and pulp) quantity in the fruiting environment played a greater role in fruit tracking than did the nutritional quality of individual fruits.While overall nutrient availability (i.e. across fruit) and total pulp mass were important determinants of fruit tracking, we suggest that plant species-specific differences in fruit nutrient concentration may be important in short-term foraging decisions involved in fruit choice and nutritional balance of birds. Fil: Blendinger, Pedro Gerardo. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Ecología Regional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Giannini, Norberto Pedro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; Argentina Fil: Zampini, Iris Catiana. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales E Instituto Miguel Lillo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto de Quimica del Noroeste; Argentina Fil: Ordóñez, Roxana Mabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto de Quimica del Noroeste; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; Argentina Fil: Torres, Sebastián. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales E Instituto Miguel Lillo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto de Quimica del Noroeste; Argentina Fil: Sayago, Jorge E.. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales E Instituto Miguel Lillo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto de Quimica del Noroeste; Argentina Fil: Ruggera, Román Alberto. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Ecología Regional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Isla, Maria Ines. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto de Quimica del Noroeste; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo; Argentina

The progressive exploitation and destruction of nesting habitat in recent years, combined with the substantial pressure from legal and illegal removal of wild nestlings and adults, justifies the development of a comprehensive study on the reproductive biology of the Turquoise-fronted Parrot (Amazona aestiva). We analyzed breeding parameters in a wild protected population of Turquoise-fronted Parrots in the Chaco forest, Argentina, examining variation among years, over the course of the breeding season, and in relation to the age of the nest. Mean clutch-size per nesting attempt was 3.68 eggs. Hatching success (proportion of eggs laid that hatch) was 0.73. Fledging success (proportion of nestlings that fledge) was 0.88. The overall breeding success (mean number of fledglings per laying female per year) was 0.95. Clutch size did not vary among years but it decreased with the delay of the nest initiation date. Hatching failure was the greatest cause of egg partial losses, and brood reduction was the main cause of nestling partial loses. Brood reduction was positively correlated with clutch size and with egg-laying date. We did not find interannual variation in any of the clutch or brood size variables. Our results showed that the population of Turquoise-fronted Parrots in the dry Chaco forest has high values of clutch size and nestling survival, and low values of hatching success. However, some aspects of the breeding biology need more attention, especially if the species continues to be harvested. L'exploitation et la destruction progressives de l'habitat de nidification advenues ces récentes années, combinées à la pression élevée de captures légale et illégale d'oisillons et d'adultes sauvages, justifient la mise en place d'une étude globale sur la biologie de reproduction de l'Amazone à front bleu (Amazona aestiva). Nous avons analysé les paramètres de reproduction d'une population sauvage protégée de cette amazone dans la forêt du Chaco, en Argentine, examinant les variations interannuelles, tout au long de la saison de reproduction, en relation avec l'âge du nid. La taille moyenne de la ponte par tentative de nidification était de 3,68 oeufs. Le succès d'éclosion (proportion d'oeufs pondus qui ont éclos) était de 0,73. Le succès à l'envol (proportion de jeunes qui ont pris leur envol) était de 0,88. Le succès de nidification d'ensemble (nombre moyen de jeunes à l'envol par femelle nicheuse par année) était de 0,95. La taille de la ponte n'a pas varié d'une année à l'autre, mais était plus faible lorsque la date d'initiation du nid était retardée. L'échec de l'éclosion était la cause la plus importante de perte partielle d'oeufs et une couvée réduite était la cause principale de perte partielle d'oisillons. La couvée réduite était positivement corrélée avec la taille de la ponte et la date de celle-ci. Nous n'avons pas observé de variations interannuelles des variables relatives à la taille de la ponte ou de la couvée. Nos résultats indiquent que la population de l'Amazone à front bleu de la forêt sèche du Chaco montre des valeurs élevées de la taille de ponte et de la survie des oisillons, mais des valeurs faibles du succès d'éclosion. Néanmoins, nous pensons qu'il serait important de se pencher davantage sur certains éléments de la biologie de reproduction de l'espèce, particulièrement si elle continue d'être prélevée. Fil: Berkunsky, Igor. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto Multidisciplinario de Ecosistemas y Desarrollo Sustentable; Argentina Fil: Segura, Luciano Noel. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico Zoología Vertebrados; Argentina Fil: Ruggera, Román Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina Fil: Faegre, Sarah I. K.. University of Washington; Estados Unidos Fil: Trofino Falasco, Clara. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Instituto Multidisciplinario de Ecosistemas y Desarrollo Sustentable; Argentina Fil: López, Fernando Gabriel. 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; Argentina Fil: Velasco, Melina Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología de Vertebrados. Sección Herpetología; Argentina Fil: Kacoliris, Federico Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico Zoología Vertebrados; Argentina Fil: Aramburu, Rosana Mariel. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico Zoología Vertebrados; Argentina Fil: Reboreda, Juan Carlos. 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

In visually driven seed dispersal mutualisms, natural selection should promote plant strategies that maximize fruit visibility to dispersers. Plants might increase seed dispersal profitability by increasing conspicuousness of fruit display, understood as a plant strategy to maximize fruit detectability by seed dispersers. The role of different plant traits in fruit choice and consumption by seed dispersers has been broadly studied. However, there is no clear evidence about the importance of the traits that increase conspicuousness of fruit display. Because strategies to maximize conspicuousness of fruit display are diverse, and usually are expected to be costly, we would expect that individual plant species will produce an efficient combination of traits. We explored this prediction with 62 fleshy fruited plant species of a subtropical Andean forest (Southern Yungas), and using a large dataset of fruit consumption by birds (4476 records). Conspicuousness of fruit display was characterized by both fruit and plant traits including chromatic contrast, size, exposure, aggregation and crop size of fruits. We also considered phylogenetic effects on phenotypic variation. Fruit consumption was explained by fruit chromatic contrast depending on fruit crop size. These traits revealed low phylogenetic effects, with the exception of four plant clades at different levels in the phylogenetic tree. Negative correlations between pairs of traits support our assumption that fruit display traits are costly, suggesting natural selection favours parsimonious evolutionary pathways. Plant species seem to rely on conspicuousness of fruit display by a combination of traits that might minimize costs of fruit display. This appears adaptively relevant to improve communication with mutualistic animals, to increase fruit consumption in a community context and, ultimately, to enhance the profitability of seed dispersal. A lay summary is available for this article. Fil: Ordano, Mariano Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; Argentina. Fundación Miguel Lillo; Argentina Fil: Blendinger, Pedro Gerardo. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentina Fil: Lomascolo, Silvia Beatriz. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentina Fil: Chacoff, Natacha Paola. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentina Fil: Sanchez, Mariano Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú; Argentina Fil: Nuñez Montellano, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; Argentina Fil: Jiménez, Julieta. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentina Fil: Ruggera, Román Alberto. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina Fil: Valoy, Mariana. Fundación Miguel Lillo; Argentina

The interactions between birds that use tree cavities for breeding, roosting and sheltering have been named ‘nest webs’. We applied for the first time in nest-web studies some tools developed in network theory, in order to develop conservation and management recommendations of forest biodiversity. We recorded 109 interactions between 15 bird and 11 cavity-bearing tree species, in a subtropical piedmont forest (PF) of northwestern Argentina. Bird species in this nest-web included four woodpecker species, whose cavities were scarcely (9%) used by non-excavator birds, such as parrots, owls, and woodcreepers. Based on the Importance and Strength indices the most important tree species were Calycophyllum multiflorum (Rubiaceae) and Anadenanthera colubrina (Fabaceae). The nest web contained three main interaction modules: one composed by woodpeckers interacting with both living and standing dead trees; another by non-excavator birds using decay-formed cavities in living trees; and a third small module that had a few birds using woodpecker-excavated cavities in living trees. Important tree species were different for woodpecker and non-excavator modules. Extinction simulation of the most important tree species tripled the negative impact on cavity-using bird assemblage compared with the random extinction of tree species. In logging operations special consideration should be taken to ensure the maintenance of key tree species for the conservation of all the nest-web components in PF. Fil: Ruggera, Román Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Jujuy. Universidad Nacional de Jujuy. Centro de Investigaciones y Transferencia de Jujuy; Argentina. Fundación CEBio; Argentina Fil: Schaaf, Alejandro Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Jujuy. Universidad Nacional de Jujuy. Centro de Investigaciones y Transferencia de Jujuy; Argentina. Fundación CEBio; Argentina Fil: Vivanco, Constanza Guadalupe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Jujuy. Universidad Nacional de Jujuy. Centro de Investigaciones y Transferencia de Jujuy; Argentina. Fundación CEBio; Argentina Fil: Politi, Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Jujuy. Universidad Nacional de Jujuy. Centro de Investigaciones y Transferencia de Jujuy; Argentina. Fundación CEBio; Argentina Fil: Rivera, Luis Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones y Transferencia de Jujuy. Universidad Nacional de Jujuy. Centro de Investigaciones y Transferencia de Jujuy; Argentina. Fundación CEBio; Argentina

Seed dispersal networks are often organized in nested structures in a way that a few core species can disproportionally affect the remaining species in a network, in both the ecological and evolutionary sense. Yet, the relative importance of core and peripheral species has not been properly tested in seed dispersal network studies. We determined core species from 10 local seed dispersal networks composed by fleshy-fruited plants and frugivorous birds. Each of those local quantitative networks was characterized with a core quality value, a core score for each species and a threshold value between core and peripheral species. From a total of 52 bird and 69 plant species that interacted in the study area, only 8 and 15, respectively, were identified as core. Each local network had a core that comprised a small number of birds and plants, always lower than 30% of the interacting species. There was no difference in the quantitative component of seed dispersal effectiveness (QC) provided by the frugivorous bird assemblage to plant functional groups clustered according to their growth form and fruit characteristics. Core birds dispersed seeds from each of these plant functional groups with a higher QC than peripheral species. Thus, we empirically demonstrate for the first time that seed dispersal networks at a regional scale have a small core set of fruit-eating birds, upon which heavily rely most fleshy-fruited plants for their seed removal. Hence, the activity of just a few core frugivores could deeply impact the demography of an entire assemblage of fleshy-fruited plants. Fil: Ruggera, Román Alberto. Universidad Nacional de Jujuy; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucumán; Argentina Fil: Blendinger, Pedro Gerardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucumán; Argentina Fil: Gomez, Maria Daniela. Universidad Nacional de Jujuy; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Marshak, Charlie. University of California at Los Angeles; Estados Unidos

1. The fruit-tracking hypothesis predicts spatiotemporal links between changes in the abundance of fruit-eating birds and the abundance of their fleshy-fruit resources. 2. While the spatial scale of plant-frugivore interactions has been explored to understand mismatches between observed and expected fruit-frugivore patterns, methodological issues such as the consequences of measuring fruit and frugivore abundance rather than fruit availability and fruit consumption have not been evaluated. 3. Here, we explored whether predicted fruit-frugivore spatiotemporal links can be captured with higher accuracy by proximate measurements of interaction strength. We used a 6-ha grided plot in an Andean subtropical forest to study the link between (i) fruit and fruit-eating bird abundances; (ii) fruit availability and frequency of fruit consumption; and (iii) covariation between frugivore abundance and frequency of frugivory. We evaluated these links for the entire frugivore assemblage and for the four most important species using data gathered bimonthly along a 2-year period. 4. Fleshy-fruit availability and abundance varied sharply temporally and were patchily distributed in mosaics that differed in fruit quantity. Fruit availability and abundance also varied along spatial gradients extended over the whole study plot. We found a strong response of the entire frugivorous bird assemblage to fruit availability over time, and a weakly significant relationship over space at the local scale. The main frugivore species widely differed in their responses to changes in fruit abundance in such a way that response at the assemblage level cannot be seen as the sum of individual responses of each species. Our results suggest that fruit tracking in frugivorous-insectivorous birds may be largely explained by species-specific responses to changes in the availability of fruits and alternative resources. 5. In agreement with our prediction, more accurate measurements of interaction strength described fruit-frugivore relationships better than traditional measurements. Moreover, we show that covariation between frugivore abundance, frequency of fruit consumption and fruit availability must be included in the fruit-tracking hypothesis framework to demonstrate (or reject) spatiotemporal fruit tracking. We propose that estimation of nutrient and energy availability in fruits could be a new frontier to understanding the forces driving foraging decisions that lead to fruit tracking. © 2012 British Ecological Society. Fil: Blendinger, Pedro Gerardo. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentina Fil: Ruggera, Román Alberto. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentina Fil: Nuñez Montellano, Maria Gabriela. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentina Fil: Macchi, Leandro. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentina Fil: Zelaya, Patricia Viviana. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentina Fil: Alvarez, María Evangelina. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentina Fil: Martín, Eduardo. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentina Fil: Osinaga Acosta, Oriana. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentina Fil: Sánchez, Rocío. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentina Fil: Haedo, Josefina. Universidad Nacional de Tucumán. Instituto de Ecología Regional. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Ecología Regional; Argentina

The stability and dynamics of multispecies interactions often rely on a small core of species. We examine whether the Yellow-striped Brush-Finch (Atlapetes citrinellus), the only species of bird endemic to the Argentinean Yungas, is a core species for seed dispersal. Of 30 species of fleshy fruit consumed, 16 were dispersed through endozoochory. The Yellow-striped Brush-Finch mostly used the ‘cut or mash’ method of handling fruit, in which reasonably large seeds (>0.04 g) were discarded or swallowed equally. Medium-sized and small seeds were more often swallowed than discarded. Although the fruits consumed were mostly understorey species, there was no difference in the consumption of fruit from forest understorey or canopy when total fruit abundance in vertical strata was considered. By using interaction network metrics, we determined that the role of Yellow-striped Brush-Finches in seed dispersal during the rainy season was more important at higher altitudes and in the southern sector of its distribution. Our findings support the idea that the Yellow-striped Brush-Finch must be considered a core seed-disperser of understorey and canopy fruits. Use of network metrics is an effective way to assess the importance of individual species in a network, allowing restoration and conservation efforts to be focussed on environments in which these species occur. Fil: Ruggera, Román Alberto. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Ecología Regional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Gomez, Maria Daniela. Universidad Nacional de Jujuy. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Blendinger, Pedro Gerardo. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto de Ecología Regional; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina