Abstract: In the temperate austral forests endozoochory is crucial for many plants with fleshy fruits, birds being the biggest consumers of fruits and seed dispersers. The Austral thrush Turdus falcklandii is a resident bird that consumes fruits of Myrceugeia planipes, increasing seed germination and reducing the time required for the appearance of the hypocotyl, which translates into competitive advantages for new individuals.

Resumen: En los bosques templados australes la endozoocoría es determinante para muchas plantas con frutos carnosos, siendo las aves los mayores consumidores de frutos y dispersores de semillas. El zorzal austral Turdus falcklandii, es un ave residente que consume frutos de la pitra Myrceugenia planipes, incrementando la germinación de las semillas y reduciendo el tiempo requerido para la aparición del hipocótilo, lo que se traduce en ventajas competitivas para los nuevos individuos.

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.

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.

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.