Unusual Behavior in Parental Care by a House Wren (Troglodytes aedon): Post Fledging Use of an Old Nest During Cold Nights

I report on the unusual behavior of an adult House Wren (Troglodytes aedon) leading recently fledged young back to the nest for two consecutive nights. The ambient temperature reached below 0°C during both nights. Despite disadvantages associated with remaining in the nest, this observation suggests that adult birds may assess trade-offs between perceived risks versus the benefits of engaging in other activities, in this case roosting communally for thermoregulation

Factors Associated with Flammulated Owl and Northern Saw-Whet Owl Occupancy in Southern Idaho

Spatially explicit models depicting species occupancy offer a useful conservation tool for land managers. Using occurrence data collected in 2009 and 2010 from the Boise National Forest, Idaho, we developed distribution models for Flammulated Owls (Psiloscops flammeolus) and Northern Saw-whet Owls (Aegolius acadicus) to explore associations between habitat factors and owl occupancy. We then spatially applied these models in a Geographic Information System. We considered land cover and topographic variables at three spatial scales: 0.4-km, 1-km, or 3-km-radius plots centered on point-count locations (n  =  150) with resolution of land covers at 30 m. Flammulated Owls occupied 27 (18%) point-count locations and occurred in areas with a higher proportion of Douglas-fir (Pseudotsuga menziesii) at the 0.4-km scale, less diverse land cover composition at the 1-km scale, and in south-facing aspects at the 3-km scale. Northern Saw-whet Owls occupied 45 (30%) point-count locations and were associated with relatively flat terrain at the 0.4-km scale that had larger proportions of non-forest land cover. At the 1-km and 3-km scales, Northern Saw-whet Owls occurred in areas with south-facing aspects having a higher proportion of ponderosa pine (Pinus ponderosa), respectively. Biologists and land managers interested in the conservation of Flammulated Owls and Northern Saw-whet Owls can use our approach to delineate habitats important for these owls or to help identify locations suitable for restoration

MOLT PATTERNS AND SEXING AND AGING CRITERIA FOR TEN SPECIES OF HIGH ELEVATION LANDBIRDS FROM SOUTHEASTERN PERU

Abstract ∙ Knowledge of molt patterns and their resulting plumages is useful for aging and sexing birds and, in mono‐ chromatic species, morphometric measurements can help to discern males from females. However, these data are largely undescribed for the majority of the world’s bird species, especially in the tropics. We sought to classify the molt strategy for 10 species of Neotropical passerines during their breeding seasons and considered whether a combination of wing chord, tail length and mass could be used to determine their sex. We used banding data from three years of mark‐recapture study at Wayqecha Biological Station (2900 m a.s.l.) along the east slope of the Andes in southeastern Peru to characterize molt and estimate morphological measurements. Each of the species exhibited a complete definitive prebasic molt and either a partial (nine species) or partial‐incomplete (one species) preformative molt, which we interpreted to be consistent with a complex basic molt strategy. For five of the 10 species, we found that wing, tail, and body mass measurements were useful in distinguishing between males and females. This study contributes to our understanding of tropical bird molt by providing previously undescribed aging and sexing criteria for some tropical landbirds common to high elevations of southern Peru.Resumen ∙ Patrones de muda y criterios para categorizar sexo y edad en diez especies de aves altoandinas en el sureste de Perú Los patrones de muda en la mayoría de las aves Neotropicales son poco conocidos y en especial se desconoce si las medidas corporales pueden ser usadas para determinar el sexo en especies sin dimorfismo sexual. En este trabajo clasificamos la estrategia de muda para 10 especies de paserinos Neotropicales y también exploramos si una combi‐ nación de medidas de longitud del ala, longitud de la cola y masa corporal pueden ser usadas para la determinación del sexo. Usamos datos de anillamiento de tres años de un estudio de recaptura en la Estación Biológica Wayqecha (2900 m s.n.m.) en el flanco oriental de los Andes al sureste de Perú. Cada especie exhibió una estrategia básica compleja de muda con una muda prebásica definitiva compleja, y una muda preformativa parcial (nueve especies) o parcial‐incompleta (uno especie). Para cinco de cada 10 especies, la combinación de medidas de la longitud del ala, la cola, y la masa corporal sirvieron para distinguir entre machos y hembras. Este estudio contribuye a la creciente literatura sobre los patrones de muda en aves tropicales y provee herramientas para clasificar la edad y el sexo de aves con plumaje sexualmente monocromático

Variable Shifts in the Autumn Migration Phenology of Soaring Birds in Southern Spain

While alteration of the migratory habits of birds is widely regarded as one of the most evident ecological effects of climate change, studies reporting shifts in migration phenology for long-lived, long-distance migrants have been few. Using time series of count data collected in southern Spain during autumn migration, we examined the magnitude and direction of phenological shifts for six common species of soaring birds. Many current methods for investigating phenological change rely on continuous data sets; however, these data may be unavailable for a variety of reasons. We used a cross-correlation analysis, which allowed us to compare recent data on the timing of migration from 1999–2011 to a historic data set collected during 1976–1977. The direction of phenological shifts for autumn migration was species-specific. White Storks Ciconia ciconia and Black Kites Milvus migrans appeared to have delayed passage, Black Storks Ciconia nigra and European Honey Buzzards Pernis apivorus have advanced their migratory timing, and we found no clear phenological change for Short-toed Eagles Circaetus gallicus or Booted Eagles Hieraaetus pennatus

Patterns of co-occurrence in woodpeckers and nocturnal cavity-nesting owls within an Idaho forest

Few studies have examined the patterns of co-occurrence between diurnal birds such as woodpeckers and nocturnal birds such as owls, which they may facilitate. Flammulated Owls (Psiloscops flammeolus) and Northern Saw-whet Owls (Aegolius acadicus) are nocturnal, secondary cavity-nesting birds that inhabit forests. For nesting and roosting, both species require natural cavities or, more commonly, those that woodpeckers create. Using day and nighttime broadcast surveys (n = 150 locations) in the Rocky Mountain biogeographic region of Idaho, USA, we surveyed for owls and woodpeckers to assess patterns of co-occurrence and evaluated the hypothesis that forest owls and woodpeckers co-occurred more frequently than expected by chance because of the facilitative nature of their biological interaction. We also examined co-occurrence patterns between owl species to understand their possible competitive interactions. Finally, to assess whether co-occurrence patterns arose because of species interactions or selection of similar habitat types, we used canonical correspondence analysis (CCA) to examine habitat associations within this cavity-nesting bird community. We found that Flammulated Owls co-occurred more with Hairy Woodpeckers (Picoides villosus), Northern Saw-whet Owls co-occurred with Northern Flickers (Colaptes auratus) and Red-naped Sapsuckers (Sphyrapicus nuchalis) and, when primary excavators were considered as a group, each species of owl was positively associated with the presence of woodpeckers. The owl species were distributed independently of one another suggesting a lack of competitive interactions. The CCA had relatively low explanatory power but suggested that habitat associations alone did not explain the patterns of positive co-occurrence we observed: Flammulated Owls and Hairy Woodpeckers associated with different habitats and Northern Saw-whet Owls, Northern Flickers, and Red-naped Sapsuckers appeared as habitat generalists. We interpret these patterns of co-occurrence and habitat use as evidence that woodpeckers facilitate presence of these species of owl and suggest management for forest owls could also include focus on the diurnal species with which they appear to associate

Variable shifts in the Autumn migration phenology of soaring birds in southern Spain

While alteration of the migratory habits of birds is widely regarded as one of the most evident ecological effects of climate change, studies reporting shifts in migration phenology for long-lived, long-distance migrants have been few. Using time series of count data collected in southern Spain during autumn migration, we examined the magnitude and direction of phenological shifts for six common species of soaring birds. Many current methods for investigating phenological change rely on continuous data sets; however, these data may be unavailable for a variety of reasons. We used a cross-correlation analysis, which allowed us to compare recent data on the timing of migration from 1999-2011 to a historic data set collected during 1976-1977. The direction of phenological shifts for autumn migration was species-specific. White Storks Ciconia ciconia and Black Kites Milvus migrans appeared to have delayed passage, Black Storks Ciconia nigra and European Honey Buzzards Pernis apivorus have advanced their migratory timing, and we found no clear phenological change for Short-toed Eagles Circaetus gallicus or Booted Eagles Hieraaetus pennatus.This study was funded by grants of the Regional Ministry for Environment of Andalusia and The Board of Fundación Migres