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congresos y reuniones científicas
Título:
CARDINAL ORIENTATION OF CAVITIES EXCAVATED BY BIRDS IN THE NEOTROPICS: RELATIONSHIP WITH MACRO-ENVIRONMENTAL ATTRIBUTES
Autor/es:
OJEDA VALERIA; COCKLE CRISTINA; POLITI NATALIA; RIVERA LUIS
Reunión:
Congreso; Ornithological Congress of the Americas; 2017
Resumen:
">The microclimate of avian nest and roost sites affects reproduction and survival;therefore, environmental placement of these structures is of adaptive significance. Ithas been hypothesized that, to optimize thermal properties, at higher latitudes avianexcavators should orient their cavities more toward the equator. In support of this, ameta-analysis of cavity entrance orientation of Northern Hemisphere woodpeckersshowed that with increasing latitude cavities were oriented more toward the south. Wetested this hypothesis, with the inverse prediction (dominance of north orientations aslatitude increases), for cavities excavated in the Southern Hemisphere, with data fromnine Neotropical ecorregions, including tropical to subpolar sites (~16-55° S, ~48-72° W).We recorded orientations for nests and/or roosts (n=1511) excavated in trees, poles,and terrestrial termite mounds by 25 species varying in size, from Picumnus toCampephilus. Based on several generalized linear models, we found that macroenvironmental variables (such as altitude, latitude, or ecorregion) failed to predictorientation. Cavities were randomly oriented in Cerrado, Chaco, Atlantic Forest andPampas ecorregions. However, they were non-random in Yungas and Monte (facingwest-southwest), Espinal (north), Valdivian (east) and Magellanic (north-northeast)ecorregions. These results do not support the prediction that at higher latitude birdsorient their cavities more toward the equator, and cast doubt on latitude as a globaldriver of cavity orientation. Other macro-environmental variables (such as reduced150continentality in the southern Neotropics) might cancel out the effects of latitude.Further, local variables may explain the patterns occurring at each ecorregion