Tomás A. Altamirano

Rufous-legged Owl (Strix rufipes) and Austral Pygmy Owl (Glaucidium nanum) stand use in a gradient of disrupted and old growth Andean temperate forests, Chile

We studied how human induced structural changes in forests affect stand use of the Rufous-legged Owl (forest-specialist) and the Austral Pygmy Owl (forest-facultative), in a gradient from lowland disrupted forests to protected Andean forests in Chile. We also tested if the calls of one species influenced the calling behaviour of the other. We detected a total of 34 Rufous-legged Owls and 21 Austral Pygmy Owls during the four seasons. Rufous-legged Owls were found principally in old growth Araucaria-Nothofagus stands (32.4%), and Pygmy Owls in old growth evergreen stands (52.4%). For both species there was a seasonal effect on call response, with a drop in responses in autumn and winter. Our models suggested that Rufous-legged Owls inhabit a more specific range of habitat characteristics than Pygmy Owls. The former selected stands with tall trees, relatively low tree density, and high bamboo density. Pygmy Owls selected stands with tall trees and relatively high tree density. There was no evidence that either species influenced the calling behaviour of the other, suggesting no negative association between use of a territory by the two species. Our results emphasize the importance of structural components of old growth forests for both species, but also the relevance of stands surrounding protected areas. Estudiamos cómo los cambios estructurales en el bosque, inducidos por el ser humano, afectan el uso de hábitat del concón (especialista de bosque) y del chuncho (facultativo de bosque), en un gradiente desde bosques perturbados en zonas bajas hasta bosques andinos protegidos de Chile. También evaluamos si los llamados de una especie influencian el comportamiento de vocalización de la otra. Detectamos un total de 34 concones y 21 chunchos para las cuatro estaciones del año. Los concones fueron registrados principalmente en bosques antiguos de Araucaria-Nothofagus (32.4%), y los chunchos en bosques antiguos siempre-verdes (52.4%). Para ambas especies hubo una disminución de la actividad en otoño e invierno. Nuestros modelos sugirieron que el concón tiene requerimientos de hábitat más específicos que el chuncho. El concón seleccionó bosques con árboles altos y en baja densidad relativa, y una alta densidad de quila. Por su parte, el chuncho seleccionó bosques con árboles altos y en alta densidad relativa. No hubo evidencia de que los llamados de una especie afectaran las respuestas de la otra, sugiriendo que no existe una asociación negativa en el uso de un mismo territorio por ellas. Los resultados enfatizan la importancia de los elementos estructurales de los bosques antiguos para ambas especies pero, a su vez, la relevancia de los bosques periféricos a áreas protegidas.

Güiña (Leopardus guigna) preys on cavity-nesting nestlings

1Fauna Australis Wildlife Laboratory, Department of Ecosystem and Environment, School of Agricultural and Forests Sciences, Pontifi cia Universidad Católica de Chile. CP 7820436, Chile 2The Peregrine Fund, 5668 W Flying Hawk Lane, ID 83709, Boise, Idaho, USA 3Department of Wildlife Ecology and Conservation, University of Florida, 110 Newins-Ziegler Hall, Gainesville, FL 32611-0430, USA 4National Forestry Service (CONAF), Protected Areas Management, Department of Biodiversity Conservation. CP 8330407, Chile *Corresponding author: taaltami@uc.cl

Reproductive life-history variation in a secondary cavity-nester across an elevational gradient in Andean temperate ecosystems

ABSTRACT Avian reproductive strategies have been hypothesized to vary with elevation. Shorter breeding seasons due to harsh environmental conditions, and potentially higher predation risks, may reduce clutch sizes at higher elevations, which in some species leads to increased parental care and offspring survival. However, this phenotypically plastic and potentially adaptive response has been documented only in a handful of species in the Northern Hemisphere. For the first time in a southern temperate ecosystem, we studied whether the breeding strategy of a secondary cavity-nester varied along an elevational gradient in Andean temperate forests, Chile. We installed 240 nest-boxes at 260–1,115 m elevation and monitored the breeding activity of 162 nests of Thorn-tailed Rayaditos (Aphrastura spinicauda) over 2 seasons (2010–2012). We included 50 nests from a third season only for recording clutch size and nestlings per clutch. As predicted, the breeding season was shorter in highland forests than in lower elevations, by 28% and 55% over the 2 successive seasons. Although timing of egg laying (1 egg every second day) and incubation period (average = 15 days) did not vary with elevation, we found smaller clutch sizes (average = 4.1 vs. 4.5) and fewer nestlings per clutch (average = 3.5 vs. 4.2) at higher elevations. The extent of parental care, expressed as the duration of the nestling period, was slightly but significantly greater in highland than in lowland forests (22.2 vs. 21.6 days). Despite the longer nestling period at higher elevations, nesting success was lower at high elevations, mainly because of nest predation. Our findings suggest that Thorn-tailed Rayaditos may change to a slower reproductive strategy along elevational gradients. Yet these changes do not appear to compensate for the increased predation rates at higher elevations, calling into question the potential adaptive significance of this strategy.

Diversidad y singularidad de la avifauna en turberas esfagnosas australes de la Reserva de Biosfera Cabo de Hornos, Chile

Sphagnum -dominated peat bogs that are strongly embedded within the southern temperate forest matrix are increasingly being used for agriculture. Nevertheless, little is known about their biodiversity. Moreover, the remote areas of southern Chile where peat bogs are found, such as the Cape Horn Biosphere Reserve (CHBR, 54-55oS), where birds are the most diverse and best represented group of vertebrates, have not been wellinvestigated. With the aim to broaden this knowledge in the CHBR, we studied the diversity of the avian assemblage in peat bogs on Navarino Island. We compared the composition of avian species between wetlands with and without peat bogs to test if Sphagnum bogs represented a singular habitat for birds in this area. Furthermore, the 37 bird species recorded in these habitats were classified according to guild structure. The community similarity values showed that peat bogs hosted a bird composition that was different from that present in wetlands without Sphagnum , suggesting that peat bogs are a singular type of habitat for birds in the CHBR. The most frequently feeding groups recorded in these wetlands were insectivores (48.7%), followed by omnivores (23.1%). Our results showed that, in contrast to previous studies of birds in peat bogs, these environments constituted a distinct wetland habitat for feeding, reproduction and sheltering for some species in the CHBR. Thus, plans for the conservation and rational use of peat ecosystems should consider the high value of these habitats for biodiversity on a landscape scale, especially for birds of the southernmost extreme of the Americas. Las turberas esfagnosas que se encuentran fuertemente embebidas en la matriz de bosques templados australes, se utilizan de forma creciente en agricultura. Sin embargo, el conocimiento de su biodiversidad es escaso. Mas aun, zonas remotas del sur de Chile donde se encuentran las turberas, como la Reserva de Biosfera Cabo de Hornos (RBCH, 54-55o S), donde las aves constituyen el grupo de vertebrados mas diverso y representativo, aun han sido escasamente estudiadas. Con el objetivo de aportar en su conocimiento en la RBCH, se estudio la diversidad del ensamble de aves en turberas esfagnosas de la isla Navarino. Se exploro si su composicion especifica es igual al de los humedales sin turbera, probando si las turberas constituyen o no un habitat singular para las aves. Tambien se clasifico a las 37 especies de aves registradas en estos habitats de acuerdo a la estructura de gremios. Los valores de similitud taxocenotica senalaron que la composicion de aquellos con turbera difirio de aquellos sin turbera, sugiriendo que este habitat es singular para las aves. El tipo de alimentacion mas frecuente fue la insectivoria (48,7%), seguido por la omnivoria (23,1%). Los resultados muestran que, a diferencia de lo senalado en trabajos previos sobre aves de turberas, estos ambientes constituyen un humedal-habitat singular para la alimentacion, reproduccion y refugio de algunas especies en la RBCH. De esta manera, la conservacion y uso racional de turberas debe considerar el valor que tienen como habitat para la biodiversidad a escala de paisaje, especialmente para las aves del extremo sur americano.

Observations of a Tree-cavity Nest of the Rufous-legged Owl and Predation of an Owl Nestling by a Chimango Caracara in Andean Temperate Forests

Andean temperate ecosystems have lower avian species richness than other temperate, subtropical, and Andean forest types, but they contain many endemic species (e.g., 41% for birds; Vuilleumier 1985). Because of its high concentration of endemism and exceptional loss of native forest habitat (approximately 70%), the Andean temperate ecosystem is classified as a Global Biodiversity Hotspot (Myers et al. 2000). The Rufous-legged Owl (Strix rufipes) is an endemic forest-specialist raptor once considered one of the least-known owls in South America; this species has declining populations because of increasing habitat loss (Martı́nez and Jaksic 1996). Recent studies have shown that this species tolerates some habitat disturbance, but still requires a complex forest-stand structure comprising large, decaying trees, dead standing trees (snags), and a dense understory (Ibarra et al. 2014b, Ibarra and Martin 2015). Rufous-legged Owls in temperate forests are sit-and-wait predators with a diet composed mainly of arboreal and scansorial small mammals, but also smaller proportions of forest passerines and invertebrates (Martı́nez 1993, Martı́nez and Jaksic 1997, Figueroa et al. 2006, 2016). The few reported nests described for Rufous-legged Owls include one likely unusual nest on the ground in a pine (Pinus radiata) plantation (Estades 1998), and six cavity nests in large, decaying native trees (Vukasovic et al. 2006, Wallace 2010, Beaudoin and Ojeda 2011). In all these cases, however, information on Rufous-legged Owl nesting activity (e.g., incubation period, adult parental behavior, prey consumption) and nest fate was lacking. Secondary Andean temperate forests and open areas are readily utilized by the Chimango Caracara (Milvago chimango), a common, yet poorly studied raptor (Figueroa 2015). This habitat generalist raptor feeds on carrion, human rubbish, invertebrates, lizards, small mammals, and 1 Email address: jtibarra@uc.cl

Roosting records in tree cavities by a forest-dwelling bat species (Histiotus magellanicus) in Andean temperate ecosystems of southern Chile

Tree cavities can provide critical roosting sites for cavity-using vertebrates. These sites can directly affect productivity and survival of bats. Histiotus magellanicus, one of the bat species with the southernmost distribution in the world, is suspected to use tree cavities, under bark, caves and human buildings for roosting. We document the first records of this bat roosting in tree cavities created by both cavity-facilitators (i.e., excavators) and tree-decay processes on standing dead and large decaying trees in Andean temperate forests, southern Chile. Our records contribute to improve current knowledge of roosting habitat of H. magellanicus. We discuss these natural history records on roosting site selection and the potential importance of tree cavities for this species in southern temperate ecosystems.

Seasonal dynamics of avian guilds inside and outside core protected areas in an Andean Biosphere Reserve of southern Chile

ABSTRACT Capsule: Many protected forests at high elevations show higher endemic biodiversity than unprotected habitats at low elevations. In seasonal ecosystems, however, harsh environmental conditions during winter may force individuals to move from protected forests to unprotected degraded forests in lowlands. Aims: To examine how forest types and seasons affect avian diversity and habitat-use guilds in protected and unprotected forests. Methods: Habitat and seasonal avian surveys were conducted to test forest type and seasonal differences on avian species richness, relative abundances and relative abundance of habitat-use guilds. Results: Twenty-three avian species (∼40% endemics) were recorded. Highland old growth forests showed the highest richness (4.1–4.9 species/point count). The lowest richness was recorded in mid-elevation secondary forests (3.1 species/point count). The highest relative abundances for habitat-specialist understorey users and large tree users were recorded in highland old growth forests. However, the abundance of large tree users was higher in secondary forests at low elevations during colder seasons. Conclusions: Some species and guilds may move to lower elevations outside protected areas during winter. Increasing degradation of unprotected areas will likely affect the suitability of ‘winter habitat’ for specialist guilds, and thus the ecological processes and source/sink dynamics occurring across boundaries of protected and unprotected areas.

Composición y preferencia de materiales en nidos de vertebrados nidificadores de cavidades en el bosque templado andino de Chile

La composicion y calidad de los nidos pueden afectar el exito reproductivo de vertebrados nidificadores de cavidades, brindandoles proteccion y temperatura adecuada a huevos, polluelos y crias. Entre 2010-2013, se estudio la composicion y preferencia de materiales de nidos de vertebrados nidificadores de cavidades del bosque templado andino de Chile. Se instalaron 240 cajas-nidos, obteniendo 290 nidos de tres especies de aves (Aphrastura spinicauda, Troglodytes aedon y Tachycineta meyeni) y de cuatro mamiferos (Dromiciops gliroides, Rattus rattus, Oligoryzomys longicaudatus e Irenomys tarsalis). El 90 % de los nidos correspondieron a A. spinicauda (n = 170) y D. gliroides (n = 91). Los nidos de A. spinicauda estuvieron compuestos principalmente por zarcillas de trepadoras (44,2 %) y ramas de arboles y arbustos (25,7 %). Los nidos de D. gliroides estuvieron compuestos principalmente por hojas (72,9 %) y briofitas (22,9 %). Dentro del item hojas, la hoja predominante y preferida por ambas especies fue de Chusquea spp. Aphrastura spinicauda rechazo las hojas de Lophozonia obliqua. Dromiciops gliroides rechazo las zarcillas de trepadoras. Estos resultados sugieren un rol relevante de Chusquea spp. en la ecologia reproductiva de las especies estudiadas. Los enmaranados y grandes nidos de Chusquea spp., junto con el pH acido de sus hojas, podrian proporcionar tanto una proteccion contra depredadores, como un efecto biocida contra patogenos. Chusquea spp. podria influenciar el exito reproductivo de vertebrados nidificadores de cavidades, pero su beneficio debe ser dilucidado