ABSTRACT Fruits of Gevuina avellana (Proteaceae) seem to mimic wasp-induced galls of Nothofagus dombeyi (Nothofagaceae) to escape predation by rodents, which may change both spatially and temporarily. The objective of this study was to evaluate the similarity between the fruits of G. avellana and the galls of N. dombeyi and to determine if this similarity protects fruits from predation by rodents in a disturbed temperate forest. We evaluated: i) the similarity between fruits and galls by measuring length, diameter, weight and color; and ii) the effects of galls on fruit predation by offering them to rodents in varying proportions, in a forest and a meadow, over two years. Fruits and galls showed similar phenotypes but fruits were more consumed than galls, even at low fruit frequencies, suggesting that their similarities are not due to mimicry. Fruits escaped predation more in the meadow than in the forest, particularly during the second year, thus indicating spatio-temporal variability in the phenomenon. The similarity between fruits and galls seems to be the result of phylogenetic and/or developmental constraints, rather than the result of a Darwinian coevolutionary pathway mediated by rodents. However, mimicry may happen with other dry-fruited plants inhabiting deforested habitats, which encourages further studies.

We identified the prey items and trophic categories represented in the contents of a summer-autumn (2013) sample of seven stomachs from wild boars hunted in the interior of Puyehue National Park, southern Chile. The diet included plants, animals and fungi, generally similar to previous reports from two other southern Chilean wilderness areas. This recent biological invader in the study area is characterized as an opportunistic generalist and has potential negative impacts on the fauna and flora that should be promptly evaluated.

Se identifican los ítems-presas y categorías tróficas representados en los contenidos estomacales de una muestra estival-otoñal (2013) de siete estómagos de jabalíes silvestres cazados en el Parque Nacional Puyehue, sur de Chile. La dieta del jabalí incluyó plantas, animales y hongos, siendo en general similar a la previamente documentada para dos áreas silvestres del sur de Chile. Este invasor biológico reciente en el área de estudio se caracteriza como generalista y oportunista, con potenciales impactos negativos sobre la fauna y flora que deben ser prontamente evaluados.

Dietary studies contribute to our understanding of bird ecology and are an important source of information for programs promoting the conservation of organisms. We contrasted fecal and stomach content methods of dietary analysis in the Black-faced Ibis and the Southern Lapwing, in order to evaluate the degree of sensitivity in distinguishing consumed prey. Diversity and abundance of prey detected were greater in stomach content samples than in fecal samples in both bird species. The Southern Lapwing did not show association in the number of prey, or a similarity in the taxonomic composition of preys between both methods, suggesting a lack of reliability in the fecal analysis that might lead to misunderstanding the trophic ecology of this bird species. The Black-faced Ibis, show a high association in the number of preys between both methods, and the taxonomic composition and abundance of prey in feces were concordant with that detected in the stomach contents, suggesting that the fecal analysis give reliable results which are coherent between both methods of dietary analysis; this method of analysis is, therefore, recommended, and must be complemented with molecular methods of stomach content analysis, such as the stable isotopes if the scopes of the research is to carry out long term studies.

Los estudios dietarios contribuyen a comprender la ecología de las aves y son relevantes en programas de conservación de los organismos. Contrastamos los métodos de análisis dietarios fecales y estomacales en la Bandurria y en el Queltehue, para evaluar su sensibilidad para discriminar las presas consumidas. La diversidad y la abundancia de presas detectadas fueron mayores en los estómagos que en las heces en ambas especies de aves. El Queltehue no mostró una asociación en el número de categorías tróficas, ni una similitud en la composición taxonómica de la dieta entre ambos métodos, lo que sugiere que los análisis fecales no son confiables y pueden conducir a interpretaciones erróneas de la ecología trófica de esta especie de ave. La Bandurria mostró una alta asociación en el número de presas entre ambos métodos y la composición taxonómica y abundancia de presas en las heces fue concordante con la detectada en los estómagos, sugiriendo que los análisis fecales entregan resultados confiables y coherentes entre ambos métodos de análisis dietario; se recomienda su uso complementado con métodos moleculares de análisis de contenido estomacal como los isótopos estables si el objetivo de la investigación es desarrollar estudios a largo plazo.

ABSTRACT In forest ecosystems, numerous species of insectivorous birds use certain tree species as feeding and nesting substrates. Between 2009 and 2010, the use of different floristic components as feeding substrate by the Pygarrhichas albogularis King, 1831 was evaluated in a southern Chilean secondary native forest. From a total of 13 trees and bush species, six tree species were used by P. albogularis as a feeding substrate. Tree use was limited to intermediate heights (11-20 m) and, mainly, to the trunk (40% of observations) and secondary branches (26%). Pygarrhichas albogularis showed a disproportionated use of N. dombeyi and an important use of trees with a greater age structure (DBH 81-100 cm). Nothofagus dombeyi presented a significantly greater tree bark crevice depth than E. cordifolia. In turn, covariance between crevice depth and invertebrate supply in tree bark was positive and significant. We consider bark depth and invertebrate supply to be the proximate causes explaining P. albogularis disproportionated use of Nothofagus dombeyi.

RESUMEN En ecosistemas boscosos, numerosas especies de aves insectívoras usan ciertas especies de árboles como sustrato de alimentación y de nidificación. Evaluamos el uso de Pygarrhichas albogularis King, 1831 por componentes florísticos utilizados como sustrato de alimentación en un bosque nativo en el sur de Chile entre el 2009 y 2010. De 13 especies de árboles y arbustos P. albogularis utilizó seis especies de árboles como sustrato de alimentación. El uso de los árboles se limitó a alturas intermedias (11-20 m) y principalmente utilizó el tronco (40% observaciones) y las ramas secundarias (26%) de los árboles como sustrato de alimentación. Pygarrhichas albogularis mostró un uso desproporcionado por Nothofagus dombeyi y un uso importante por árboles con la mayor estructura etárea (DAP 81-100 cm). Por su parte, N. dombeyi presentó una profundidad de las grietas de la corteza significativamente mayor que E. cordifolia. A su vez, la profundidad de las grietas covarió positiva y significativamente con la oferta de invertebrados en la corteza de los árboles. Consideramos la profundidad de la corteza y la oferta de invertebrados como las causas próximas que podrían explicar el uso desproporcionado de P. albogularis por Nothofagus dombeyi.

The consumption of seeds by animals can increase the germination probability because of seeds passage through animal guts. The loss of a native disperser by anthropogenic threats might be compensated by generalist alien seed dispersers. The aim of this work was evaluating the role of dogs (Canis lupus familiaris) and foxes (Pseudalopex spp.) for seed germination of the native fleshy-fruited tree Lithrea caustica. The effectiveness of dogs and foxes as seed dispersers of L. caustica was estimated through seed germination and post-germination viability of seeds obtained from faecal samples plus a control given by seeds collected directly from plant branches. Eleven replicates per treatment and 20 seeds per replicate were used. The experiment takes place 18 weeks with an ad libitum water supply (thermoperiod: 25.7 ± 0.1 °C/12.7 ± 0.2 °C, photoperiod: 12 h light/12 h darkness). Maximum germination occurred the week 18. The germination percentage of seeds consumed by dogs (24.5 %) did not differ significantly from the germination percentage of seeds consumed by foxes (28.2 %), although it was lower than that observed from the control (45.5 %). The post-germination viability of seeds did not differ significantly among types of seed consumers, although there was a tendency toward a lowered viability in seeds dispersed by dogs (40.5 %) rather than by foxes (80.7 %). Consequently, dogs eventually can surrogate the seed disperser role of foxes, although both mutualist animals seem to be inefficient seed dispersers of Lithrea caustica, because dogs and foxes decrease the germination capability of this fleshy-fruited native tree from central Chile.

El consumo de semillas por animales podría incrementar la probabilidad de germinación al pasar por el tracto digestivo animal. La pérdida de un dispersor nativo por causas de origen humano podría compensarse por dispersores generalistas introducidos. El objetivo de este trabajo fue evaluar el papel de los perros y zorros en la germinación y viabilidad de semillas de Lithrea caustica. Se comparó la eficacia de zorros y perros como dispersores de L. caustica mediante la germinación y viabilidad post-germinativa de semillas provenientes de heces, más un control dado por semillas colectadas directamente desde los árboles. Se consideraron 11 réplicas por tratamiento y 20 semillas por réplica. El experimento duró 18 semanas con un suministro de agua ad libitum (termoperiodo: 25,7 ± 0,1 °C y 12,7 ± 0,2 °C, y fotoperiodo: 12 h luz y 12 h oscuridad). La máxima germinación ocurrió el día 126. El porcentaje de germinación de semillas consumida por perros (24,5 %) no difirió significativamente del porcentaje de germinación de semillas consumidas por zorros (28,2 %), y ambos fueron significativamente menores que el control (45,5 %). La viabilidad de las semillas post germinación no difirió significativamente según el tipo de consumidor, aunque hubo una tendencia a que las semillas consumidas por perros fuesen menos viables (40,5 %) que las consumidas por zorros (80,7 %). Consecuentemente, los perros eventualmente pueden suplir el rol de los zorros pese a que ambos parecen ser mutualistas ineficientes de L. caustica al disminuir su capacidad germinativa, aunque no su viabilidad post germinación.

BACKGROUND: Frugivorous birds are phenologically linked to the fruits that they eat. When there is less fruit in seasonal environments, frugivorous birds complement their diet by eating invertebrates. The depth of the phenological link between frugivorous birds and their dietary resources has not been studied until now. The objective was to determine the possible phenological synchrony between the Austral thrush (Turdus falcklandii) and its dietary resource, fruits and annelids, found in the fragmented forests in the South of Chile. RESULTS: The numbers of thrushes, annelids, and fruits in fragments of native forest and anthropogenic grassland in Chile's Lake District were estimated annually. Spatial variation (i.e., forest and grassland) and seasonal variation (i.e., the period of greatest fruit growth and least fruit growth) on thrushes, annelids, and fruits were analyzed with a nonparametric Scheirer-Ray-Hare extension for the Kruskal-Wallis test. The graphic representation of the seasonal variation of thrushes, annelids, and fruits was carried out using cubic spline routines. It was found that there are seasonal changes in the dietary resources of these birds. During the period of greatest fruit production, there was a trend towards a higher number of thrushes in the forest where there was a greater availability of ripe fruit in relation to the nearby grasslands. In the grasslands, the annelids demonstrated a trend towards greater quantities in comparison with the forest. There was a positive and significant correlation between the thrushes and the annelids and fruits, indicating phenological synchrony between this bird and its dietary resources. CONCLUSIONS: Therefore, we concluded that the thrush responded numerically and functionally to the variations in its resources. The result of our research underlines the importance of grasslands in maintaining thrush populations, with this bird acting as one of the most important seed dispersers in the temperate southern forests of Chile.

Numerous vertebrates, and in particular birds, ingest stones (geo-gastrolites) to favour the breakdown and digestion of food in the muscular stomachs. Between 1993 and 1994 we evaluated the quantity, relative abundance and quality of autochthonous (geo-gastrolites) and allochthonous (pieces of glass) components of the grit in gizzards of black-faced ibis (Theristicus melanopis) inhabiting the pastures of southern Chile. Grit elements were present in 32 out of 48 (66,7%) of all gizzard analysed. A total of 572 particles were recorded from which, 69.1% corresponded to autochthonous elements and 27.8% were allochthonous particles. Both components are similar in shape; however glass contributes considerably more in terms of mass. Gender differences reveal that females consume a significantly greater number of allochthonous elements than males. We postulate the hypothesis that, due to their high energy requirements, females ingest more pieces of glass to facilitate the breakdown and digestion of food with a limited nutritional value, thus increasing their reproductive success.

Numerosos vertebrados y en particular las aves, ingieren piedras (gastrolitos) para favorecer la maceración y la digestión del alimento en los estómagos musculares. Entre 1993 y 1994 evaluamos la cantidad, abundancia relativa y calidad de componentes autóctonos (piedras) y alóctonos (trozos de vidrios) de los gastrolitos presentes en las mollejas de bandurrias (Theristicus melanopis) en praderas agrícolas del sur de Chile. Los gastrolitos se presentaron en 32 de las 48 (66,7%) mollejas analizadas. Se registró un total de 572 partículas de las cuales 69,1% fueron elementos autóctonos y 27,8% partículas alóctonas. Ambos componentes no difirieren en la forma pero los vidrios aportaron significativamente mayor masa. Las hembras consumieron un número significativamente mayor de elementos alóctonos que los machos. Postulamos la hipótesis que las hembras, con alto requerimiento energético, ingieren más trozos de vidrio para incrementar la eficiencia de maceración y digestión de alimentos con reducido valor nutricional, lo que les permitiría incrementar su éxito reproductivo.

Despite its wide distribution and use of different habitats in South America, there is little information on the lesser grison Galictis cuja (Carnivora: Mustelidae). Initially described as a generalist mammal that lives near rivers and with a catholic diet, studies in Uruguay, central Chile and Argentina have shown that this mustelid preys on native rodents and introduced lagomorphs. In this paper, the fall and winter diet of the lesser grison in a fragmented Valdivian forest remnant is documented for the first time. In these seasons, when the abundance of rodents increases, the highest standard frequency of prey in the diet of this carnivore mammal (82%) corresponds to 6 species of native rodents whose body masses ranged between 24 and 58 grams. Despite the presence of introduced European hares (Lepus europaeus) in the agricultural matrix, remains of hares were not found in the 45 fecal samples analyzed, suggesting that lesser grisons hunted their prey inside and/or at the edge of the fragment.

Pese a su amplia distribución y uso de diferentes hábitats en América del Sur existe poca información sobre el quique, Galictis cuja (Carnívora: Mustelidae). Inicialmente descrito como un mamífero generalista que vive cerca de ríos y con una dieta católica, estudios en Uruguay, Chile central y Argentina han mostrado que se especializa en roedores nativos y lagomorfos introducidos. En este trabajo se documenta por primera vez su dieta otoño-invernal en un remanente de bosque valdiviano fragmentado. En estas estaciones climáticas, donde la abundancia de roedores aumenta, la mayor frecuencia estandarizada de presas en la dieta del quique (82%) correspondió a 6 especies de roedores nativos cuyas masas corporales variaron entre 24 y 58 gramos. Pese a haber liebres europeas introducidas (Lepus europaeus) en la matriz agrícola donde se encuentra el fragmento estudiado, no se encontraron restos de ellas en las 45 muestras fecales analizadas, sugiriendo que los quiques cazaron sus presas al interior y/o en el borde del fragmento.