Bird nest orientation is affected by environmental variables determined by their geographical position as well as microclimatic conditions. In closed-cup-nesting species, nests may be oriented to avoid adverse environmental extremes such as sun exposure, wind, and rainfall, although vegetal cover may provide extra protection generating random orientation patterns. Here, we assess nest entrance orientation in Rufous Hornero (Furnarius rufus) at 11 South American sites by comparing nests well covered by vegetation (> 75% covered) from those with less or non-external vegetal protection (< 25%). We estimated and compared mean entrance orientation between northern and southern locations and levels of vegetation cover using circular statistics (n = 1291). Additionally, the influence of geographical latitude and vegetation cover on nest orientation was evaluated using linear mixed models across sites with non-random nest-orientation patterns. Results showed differences in mean orientation values between covered and uncovered nests at most locations and directed entrance orientation for uncovered nests. On the other hand, the models indicate that nest entrance orientation is not affected by the joint effect of latitude and vegetation cover and high variability between locations. Local microclimatic conditions provided by the vegetation above nests are important determinants for nest orientation in the species, although additional information about local rainfall, wind, temperature, and nesting site availability may help to determine the factors affecting orientation in the species on a local level. KeywordsNest orientation • Nest preference • South America • Ovenbird • Furnariidae Zusammenfassung Der Einfluss der geographischen Breite und der Sonneneinstrahlung auf die Nestausrichtung bei Rosttöpfern (Furnarius rufus) Die Ausrichtung von Vogelnestern wird von Umweltvariablen beeinflusst, die durch die geographische Position der Nester sowie die dortigen mikroklimatischen Bedingungen bestimmt werden. Bei Arten, die in geschlossenen Napfnestern brüten, können die Nester so ausgerichtet sein, dass sie widrige Umweltextreme, z. B. bezüglich Sonneneinstrahlung, Wind und Regen, vermeiden, wobei die Vegetation zusätzlichen Schutz bieten und zu einer zufälligen Ausrichtung des Nesteingangs führen kann. Hier untersuchen wir die Ausrichtung des Nesteingangs bei Rosttöpfern (Furnarius rufus) an 11 südamerikanischen Standorten und vergleichen stark durch Vegetation geschützte Nester (> 75% bedeckt) mit solchen, denen die Vegetation nur wenig oder gar keinen Schutz bietet (< 25% bedeckt). Wir haben die mittlere Ausrichtung des Nesteingangs abgeschätzt und mit Hilfe von Kreisstatistik zwischen nördlichen und südlichen Standorten sowie Standorten mit unterschiedlicher Vegetationsbedeckung verglichen (n = 1291). Zusätzlich haben wir den Einfluss der geographischen Breite und der Vegetationsbedeckung auf die Nestausrichtung an Standorten, an denen die Nester nicht zufällig ausgerichtet waren, mit Hilfe linearer gemischter Modelle ausgewe...

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Summary The Rufous-throated Dipper Cinclus schulzi is endemic to the Southern Yungas of north-western Argentina and southern Bolivia. The species is categorised as ‘Vulnerable’ on the IUCN Red List on the basis of small population size and restricted range. The purpose of our study was to determine the distribution of potentially suitable habitat for the Rufous-throated Dipper, estimate its population size, and assess potential distribution within strict protected areas, in north-western Argentina. We surveyed 44 rivers in the Southern Yungas of Argentina from 2010 to 2013 to determine dipper density (i.e. the number of individuals detected per km surveyed). The dipper’s potential distribution was assessed using a maximum entropy modeling approach based on 31 occurrence points and eight bioclimatic and two topographic variables as predictors. The species is dependent on mountain forest rivers, so the potential distribution was restricted to rivers. We estimated dipper population size by multiplying density by the potential distribution along rivers. Finally, we calculated the extent of suitable habitat contained within the boundaries of Argentina´s National Parks. Dipper density was 0.94 ± 1.55 individuals/km. We estimate that within north-west Argentina there are ~2,815 km of river that are potential habitat, with an area of occupancy of 141 km2 and a population size of 2,657 ± 4,355 dippers. However, of this river extent, less than 5% is within National Parks. Our results highlight the need to create new and to enlarge existing National Parks that protect the potentially suitable habitat of the species. Although more information is needed for Bolivia, the country-level area of occupancy and population size of the dipper found in Argentina provides strong evidence that the IUCN Red List classification of this species as ‘Vulnerable’ is warranted.