Browsing by Author "Altamirano, Tomas A."
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- ItemAustral Opossum adjusts to life in second-growth forests by nesting outside cavities(WILEY, 2020) Vazquez, M. Soledad; Ibarra Eliessetch, José Tomás; Altamirano, Tomas A.The Austral Opossum is one of the most unique vertebrates in Patagonian forests. It is not only endemic to this habitat; it also plays a key role acting as a seed disperser, nest predator, and is prey to species of conservation concern. However, specific information about its nesting behaviour is scattered and rudimentary at best. Here, we: (i) use personal observations along with published data to group information about nest site choice and (ii) investigate how flexible this behaviour is, examining the relative frequency of both cavity (natural and artificial) and non-cavity nests. We found that Opossums placed their nests inside cavities 50% of the time in old-growth forests but only 25% of the time inside cavities in second-growth forests. We suggest that our naturalist records, along with the previous published literature, might reflect a flexible response of the species to cavity availability. In forests suffering continuous degradation, such as Patagonian ecosystems, this flexible behaviour may increase the likelihood of population persistence in the future. This study leads to the following further questions: is Austral Opossum nesting behaviour phenotypic flexibility or plasticity? Are cavities a limiting resource for this species? Would it be more efficient for a conservation program to install nest boxes or to take actions to encourage the understory vegetation where they can nest?
- ItemBecoming tree, reconstructing memory: biocultural networks in pewen (Araucaria araucana) landscapes of the southern Andes(2024) Ibarra, Jose Tomas; Cortes, Josefina; Petitpas, Robert; Barreau, Antonia; Caviedes, Julian; Orrego, Gabriel; Riquelme-Maulen, Wladimir; Altamirano, Tomas A.Relationships between people and trees are continually unfolding in the contexts of si-tuated social-ecological systems. In current studies on social-ecological systems linked with trees, we commonly find two approaches: the first focuses on 'biological entities', examining the ecological dynamics of tree species and associated biodiversity. The se-cond approach focuses on people, analyzing 'human agency' along with historical and contemporary political or other forces shaping human-tree relationships. In this paper, we explore social-ecological systems associated with the Pewen (Araucaria araucana), one of the most iconic and sacred trees from the southern Andes. We first describe some of our own research findings on Pewen for both approaches described above. We then develop a third perspective, that we call 'relational', which highlights biocultural rela-tions and has the potential to overcome both the 'ecological/social' and the 'biological entity/human agency' dichotomies. Our relational approach allows a closer enquiry on how actors (e.g. trees and their seeds, wildlife, and people, among others) interact in complex and sympoietic biocultural networks, recognizing the biocultural memory of the system that emerges as an on-going complex of dynamics relations that must be enacted and performed on a daily basis. Furthermore, it stresses that people-pewen networks are continuously built and rebuilt in open systems subjected to historical and contemporary drivers of change
- ItemCombining point counts and autonomous recording units improves avian survey efficacy across elevational gradients on two continents(WILEY, 2021) Drake, Anna; de Zwaan, Devin R.; Altamirano, Tomas A.; Wilson, Scott; Hick, Kristina; Bravo, Camila; Ibarra Eliessetch, José Tomás; Martin, KathyAccurate biodiversity and population monitoring is a requirement for effective conservation decision making. Survey method bias is therefore a concern, particularly when research programs face logistical and cost limitations. We employed point counts (PCs) and autonomous recording units (ARUs) to survey avian biodiversity within comparable, high elevation, temperate mountain habitats at opposite ends of the Americas: nine mountains in British Columbia (BC), Canada, and 10 in southern Chile. We compared detected species richness against multiyear species inventories and examined method-specific detection probability by family. By incorporating time costs, we assessed the performance and efficiency of single versus combined methods. Species accumulation curves indicate ARUs can capture ~93% of species present in BC but only ~58% in Chile, despite Chilean mountain communities being less diverse. The avian community, rather than landscape composition, appears to drive this dramatic difference. Chilean communities contain less-vocal species, which ARUs missed. Further, 6/13 families in BC were better detected by ARUs, while 11/11 families in Chile were better detected by PCs. Where survey conditions differentially impacted method performance, PCs mostly varied over the morning and with canopy cover in BC, while ARUs mostly varied seasonally in Chile. Within a single year of monitoring, neither method alone was predicted to capture the full avian community, with the exception of ARUs in the alpine and subalpine of BC. PCs contributed little to detected diversity in BC, but including this method resulted in negligible increases in total time costs. Combining PCs with ARUs in Chile significantly increased species detections, again, for little cost.Combined methods were among the most efficient and accurate approaches to capturing diversity. We recommend conducting point counts, while ARUs are being deployed and retrieved in order to capture additional diversity with minimal additional effort and to flag methodological biases using a comparative framework
- ItemDiversity and singularity of the avifauna in the austral peat bogs of the Cape Horn Biosphere Reserve, Chile(2010) Tomas Ibarra, Jose; Anderson, Christopher B.; Altamirano, Tomas A.; Rozzi, Ricardo; Bonacic, CristianIbarra, J.T., C.B. Anderson, T.A. Altamirano, R. Rozzi, and C. Bonacic. 2010. Diversity and singularity of the avifauna in the austral peat bogs of the Cape Horn Biosphere Reserve, Chile. Cien. Inv. Agr. 37(1): 29-43. 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, 54-55 degrees S), where birds are the most diverse and best represented group of vertebrates, have not been well-investigated. 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.
- ItemEcosystem engineers show variable impacts on habitat availability for cavity nesters in South American temperate forests(2024) Lima, Cecilia Cuatianquiz; Altamirano, Tomas A.; Jara, Rocio; Price, Edwin R.; Novoa, Fernando J.; Ibarra, Jose TomasEcosystem engineers are organisms that impact their environment and co-existing species by creating or modifying habitats, and thus they play important roles as drivers of community assembly. We examined whether cavity characteristics and/or habitat attributes associated with cavities provided by 4 ecosystem engineers influence the presence of nests of 3 secondary cavity-nesting birds-Aphrastura spinicauda (Thorn-tailed Rayadito), Tachycineta leucopyga (Chilean Swallow), and Troglodytes aedon (Southern House Wren)-and whether these variations influence their reproductive success. We tested this by: (1) assessing nest presence in cavities supplied by ecosystem engineers and (2) quantifying the reproductive success of secondary cavity nesters as a function of cavity characteristics and habitat attributes supplied by ecosystem engineers. Between 2009 and 2022, we recorded 757 cavities in 546 trees in old-growth and second-growth forests in a Global Biodiversity Hotspot in the Andes of southern Chile. Insect/fungi and Pygarrhichas albogularis (White-throated Treerunner) play a key role as the primary producers of cavities. Insect/fungi generated the cavities for 82% of A. spinicauda nests and 95% of T. aedon nests; in contrast, 57% of T. leucopyga nests were cavities excavated by P. albogularis. Characteristics of cavities (size of cavity entrance, volume, and height above ground) were associated with nest presence of secondary cavity nesters and with reproductive success of A. spinicauda and T. aedon. Habitat attributes such as tree density and canopy cover influenced nest presence for A. spinicauda and T. leucopyga, but did not correlate with the reproductive success of any secondary cavity nester. Bamboo density and forest type were related to reproductive success of A. spinicauda and T. aedon. Diameter at Breast Height of trees was related to the reproductive success of T. leucopyga. This study contributes to understanding the importance of various ecosystem engineers for the conservation of secondary cavity-nesting birds in temperate forests and beyond.
- ItemLatitude does not influence cavity entrance orientation of South American avian excavators(OXFORD UNIV PRESS INC, 2021) Ojeda, Valeria; Schaaf, Alejandro; Altamirano, Tomas A.; Bonaparte, Bianca; Bragagnolo, Laura; Chazarreta, Laura; Cockle, Kristina; Dias, Raphael; Di Sallo, Facundo; Ibarra Eliessetch, José Tomás; Ippi, Silvina; Jauregui, Adrian; Jimenez, Jaime E.; Lammertink, Martjan; Lopez, Fernando; Montellano, Maria Gabriela Nunez; de la Pena, Martin; Rivera, Luis; Vivanco, Constanza; Santillan, Miguel; Soto, Gerardo E.; Vergara, Pablo M.; Wynia, Amy; Politi, NataliaIn the Northern Hemisphere, several avian cavity excavators (e.g., woodpeckers) orient their cavities increasingly toward the equator as latitude increases (i.e. farther north), and it is proposed that they do so to take advantage of incident solar radiation at their nests. If latitude is a key driver of cavity orientations globally, this pattern should extend to the Southern Hemisphere. Here, we test the prediction that cavities are oriented increasingly northward at higher (i.e. colder) latitudes in the Southern Hemisphere and describe the preferred entrance direction(s) of 1,501 cavities excavated by 25 avian species (n = 22 Picidae, 2 Trogonidae, 1 Furnariidae) across 12 terrestrial ecoregions (15 degrees S to 55 degrees S) in South America. We used Bayesian projected normal mixed-effects models for circular data to examine the influence of latitude, and potential confounding factors, on cavity orientation. Also, a probability model-selection procedure was used to simultaneously examine multiple orientation hypotheses in each ecoregion to explore underlying cavity-orientation patterns. Contrary to predictions, and patterns from the Northern Hemisphere, birds did not orient their cavities more toward the equator with increasing latitude, suggesting that latitude may not be an important underlying selective force shaping excavation behavior in South America. Moreover, unimodal cavity-entrance orientations were not frequent among the ecoregions analyzed (only in 4 ecoregions), whereas bimodal (in 5 ecoregions) or uniform (in 3 ecoregions) orientations were also present, although many of these patterns were not very clear. Our results highlight the need to include data from under-studied biotas and regions to improve inferences at macroecological scales. Furthermore, we suggest a re-analysis of Northern Hemisphere cavity orientation patterns using a multi-model approach, and a more comprehensive assessment of the role of environmental factors as drivers of cavity orientation at different spatial scales in both hemispheres.
- ItemRufous-legged Owl (Strix rufipes) and Austral Pygmy Owl (Glaucidium nanum) stand use in a gradient of disrupted and old growth Andean temperate forests, Chile(TAYLOR & FRANCIS LTD, 2012) Ibarra Eliessetch, José Tomás; Galvez, Nicolas; Gimona, Alessandro; Altamirano, Tomas A.; Rojas, Isabel; Hester, Alison; Laker, Jerry; Bonacic, CristianWe 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.
- ItemSurvival rates in the world's southernmost forest bird community(2023) Sandvig, Erik M.; Quilodran, Claudio S.; Altamirano, Tomas A.; Aguirre, Francisco; Barroso, Omar; de Aguilar, Juan Rivero; Schaub, Michael; Kery, Marc; Vasquez, Rodrigo A.; Rozzi, RicardoThe Magellanic sub-Antarctic Forest is home to the world's southernmost avian community and is the only Southern Hemisphere analogue to Northern Hemisphere temperate forests at this latitude. This region is considered among the few remaining pristine areas of the world, and shifts in environmental conditions are predominantly driven by climate variability. Thus, understanding climate-driven demographic processes is critical for addressing conservation issues in this system under future climate change scenarios. Here, we describe annual survival patterns and their association with climate variables using a 20-year mark-recapture data set of five forest bird species in the Cape Horn Biosphere Reserve. We develop a multispecies hierarchical survival model to jointly explore age-dependent survival probabilities at the community and species levels in a group of five forest passerines. At the community level, we assess the association of migratory behavior and body size with survival, and at the species level, we investigate the influence of local and regional climatic variables on temporal variations of survival. We found a positive effect of precipitation and a negative effect of El Nino Southern Oscillation on juvenile survival in the white-crested Elaenia and a consistent but uncertain negative effect of temperature on survival in juveniles and 80% of adults. We found only a weak association of climate variables with survival across species in the community and no temporal trends in survival for any of the species in either age class, highlighting apparent stability in these high austral latitude forests. Finally, our findings provide an important resource of survival probabilities, a necessary input for assessing potential impacts of global climate change in this unique region of the world.
- ItemThe conservation value of tree decay processes as a key driver structuring tree cavity nest webs in South American temperate rainforests(2018) Altamirano, Tomas A.; Tomas Ibarra, Jose; Martin, Kathy; Bonacic Salas, Cristian
- ItemTree-cavity nesting records of the American kestrel (Falco sparverius) in two Andean forest sites of southern Chile(2021) Ibarra Eliessetch, José Tomás; Novoa, Fernando J.; Altamirano, Tomas A.; Vargas, F. HernánEl cernícalo americano (Falco sparverius) nidifica en cavidades o pequeños agujeros protegidos, inclu yendo oquedades de árboles (excavadas o producidas por descomposición), galerías en paredes rocosas o arenosas, entretechos de edificios y cajas nido. La biología reproductiva de esta especie es escasamente conocida en los ecosis temas templados de América del Sur. Entre 2015 y 2020, observamos siete eventos de nidificación del cernícalo en dos cavidades de árboles en un área boscosa del sur de Chile. El tamaño de puesta fue 4˗5 huevos, la incubación duró 28˗29 días, el tamaño de nidada fue 3˗4 polluelos, los polluelos permanecieron 28˗30 días en el nido y el número de volantones fue 2˗4. Nuestras observaciones amplían la comprensión de la historia natural y biología reproductiva del cernícalo en áreas boscosas templadas del sur de Chile.
- ItemTree–cavity Nesting of Austral Pygmy–Owls (Glaucidium nana) in Andean Temperate Forests of Southern Chile(2014) Ibarra, Jose T.; Altamirano, Tomas A.; Martin, Kathy; Vargas, F. Hernan; Bonacic Salas, Cristian