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?
- 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
- 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.
- 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