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Natural history information is one of the major knowledge gaps in Neotropical ornithology. Several range-restricted and threatened species in the region are still poorly known, hindering the design of effective conservation programs. Here, we used direct observations collected at 7 localities throughout the Tropical Andes to describe habitat use and foraging ecology of the Yellowheaded Brushfinch (Atlapetes flaviceps), a species of conservation concern and endemic to Colombia. Our observational records (n = 174) indicate that this species mainly occurs in secondary forests and landscape mosaics that include patches of native vegetation and agricultural areas, but it seems to be frequently associated with the presence of regenerating vegetation in early successional stages. We found that the species' diet was mainly composed of fruits and invertebrates, although other items are occasionally included. Although our data suggest the possibility of an association between habitat type and the activity recorded, as well as temporal variation in foraging behavior, this requires more research. Our observations support the idea of this species being tolerant to humanaltered habitats, but this needs to be confirmed by measuring habitat-specific productivity and survival. The results presented here not only increase knowledge of this poorly known endemic but can be useful for the subsequent implementation of management strategies aimed at increasing the availability of high-quality habitat. Received 30 November 2020. Accepted 7 December 2021. Key words: diet, natural history, successional vegetation, transformed habitats. Tropical Andes. (Spanish)--La information sobre historia natural cs uno de los principals vacios en la omitologia Neotropical. Numerosas especies amenazadas y de rango restringido son pobrementc conocidas, lo que impide el diseno de estratcgias dc conservacion efectivas. En este estudio, usamos observaciones directas colectadas en 7 localidadcs a lo largo de los Andes tropicales para describir el uso de habitat y la ecologia de forrajeo del atlapetes de anteojos (Atlapetes flaviceps), una especie endemica de Colombia y de importancia para la conservacion. Nuestras observaciones (n--174) indican que la especie se encuentra principalmcnte en bosques secundarios y mosaicos de vegetacion nativa y areas agricolas, pero parece estar frecuentcmente asociada a la presencia de vegetacion en regeneracion y zonas de sucesion secundaria temprana. Encontramos que la dieta de la especie estuvo compuesta mayomiente de frutos e invertebrados. aunque otros items son consumidos ocasionalmente. Aunque nuestros datos sugieren la asociacion entre el tipo de habitat y la actividad registrada, asi como variacion temporal en los habitos de forrajeo, esto requiere mas investigacion. Nuestras observaciones dan soporte a la idea de que la especie tolera paisajes transformados, pero esto debe confirmarse con estimaciones de productividad y sobrevivencia. Los resultados prescntados no solo incrementan el conocimiento sobre esta especie poco conocida, sino que pueden ayudar a la implcmcntacion dc estratcgias de manejo para incrementar la disponibilidad del habitat de esta ave. Palabras clave: Andes tropicales, dieta, habitats transformados. historia natural, sucesion secundaria., Scarcity of natural history data is a major knowledge gap in Neotropical ornithology, as several species still lack basic information on habitat relationships, diet, foraging ecology, and breeding biology (Lees [...]

Abundance measures are almost non-existent for several bird species threatened with extinction, particularly range-restricted Neotropical taxa, for which estimating population sizes can be challenging. Here we use data collected over 9 years to explore the abundance of 11 endemic birds from the Sierra Nevada de Santa Marta (SNSM), one of Earth's most irreplaceable ecosystems. We established 99 transects in the "Cuchilla de San Lorenzo" Important Bird Area within native forest, early successional vegetation, and areas of transformed vegetation by human activities. A total of 763 bird counts were carried out covering the entire elevation range in the study area (~175–2,650 m). We applied hierarchical distance-sampling models to assess elevation- and habitat-related variation in local abundance and obtain values of population density and total and effective population size. Most species were more abundant in the montane elevational range (1,800–2,650 m). Habitat-related differences in abundance were only detected for 5 species, which were more numerous in either early succession, secondary forest, or transformed areas. Inferences of effective population size indicated that at least 4 endemics likely maintain populations no larger than 15,000–20,000 mature individuals. Inferences of species' area of occupancy and effective population size were lower than most values previously described, a possible consequence of increasing anthropogenic threats. At least 4 of the endemics exceeded criteria for threatened species listing and a thorough evaluation of their extinction risk should be conducted. Population strongholds for most of the study species were located on the northern and western slopes of the SNSM between 1,500 and 2,700 m. We highlight the urgent need for facilitating effective protection of native vegetation in premontane and montane ecosystems to safeguard critical habitats for the SNSM's endemic avifauna. Follow-up studies collecting abundance data across the SNSM are needed to obtain precise range-wide density estimations for all species. [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2006.11.030 Byline: Nicholas J. Bayly Abstract: The strategies adopted by birds during migration are expected to be strongly influenced by resource availability and the efficiency with which these resources are used. The migratory strategy of the sedge warbler in northwest Europe has been linked to superabundances of plum-reed aphids Hyalopterus pruni that enable birds to accumulate extensive fat reserves and make nonstop flights to sub-Saharan Africa. Food availability was therefore expected to be the main determinant of whether sedge warblers accumulated extensive reserves or not. In this study, birds were provided with an unlimited supplementary food source, but only 10 out of 24 birds accumulated large reserves. In view of this, temporal and geographical cues reflecting seasonal variations in aphid abundance are considered, in addition to food availability, to determine whether extensive fuelling occurs. Optimality models of resource use by migrants predict two modes of fuelling behaviour, as seen here, if strategies have evolved to divide a journey into an optimal number of stages or if the perception of resources at future sites varies between birds or in time/space. If sedge warbler perception of future resources reflects the temporal and geographical variation in aphid abundance in northwest Europe, then the distribution of fuelling behaviours observed here is expected. Despite some birds accumulating large fuel reserves, they did not show a high degree of sensitivity to wind conditions when initiating migratory flights. Author Affiliation: (a) The Wetland Trust, U.K. (a ) School of Life Sciences, University of Sussex, U.K. Article History: Received 23 May 2006; Revised 10 August 2006; Accepted 6 November 2006 Article Note: (miscellaneous) MS. number: 8976

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.anbehav.2005.04.008 Byline: Nicholas J. Bayly Abstract: The fuelling behaviour of long-distance migratory birds is expected to have evolved to minimize a number of potential costs associated with migratory behaviour. Optimality models have generated unique and testable predictions for some of these costs, including time, energy and predation risk. By remotely weighing free-living reed warblers, Acrocephalus scirpaceus, attracted to supplementary food, I found that the relation between their fuel deposition rate and departure load approximated to the predictions of a time-minimizing model. While the results indicated that time minimization has been an important selective force, fuel deposition rates appeared constrained at times, indicating that high rates of foraging or energy turnover have been selected against. I suggest that the need to minimize foraging intensity-dependent predation risk may be the reason for fuelling rates not being maximized. The limited variation found in the fuelling durations of reed warblers is consistent with the hypothesis that fixed fuelling durations are the behavioural mechanism by which time minimization is achieved, although there was also some evidence to the contrary. These durations are expected to have been optimized with respect to the range of fuelling conditions typically encountered and the journey ahead. Author Affiliation: School of Life Sciences, University of Sussex, U.K. Article History: Received 8 November 2004; Revised 21 December 2004; Accepted 6 April 2005 Article Note: (miscellaneous) MS. number: 8339R

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The tropical Andes are characterized by extreme topographic and climatic complexity, which has likely contributed to their outstanding current species diversity, composed of many range‐restricted species. However, little is known about how the distribution and abundance of highly mobile organisms, like long‐distance migratory birds, varies across different land covers, elevations, and climatic conditions within the Andes. We conducted 1,606 distance‐sampling point counts across the Colombian Andes, spanning elevations from 253 to 3,708 m, a range of precipitation regimes and representative land covers. We then employed a novel application of a multispecies hierarchical modeling approach to evaluate how elevation, local land cover, aboveground woody biomass, cloud cover, precipitation, and seasonality in precipitation shape the abundance of the migratory land bird community in the Andes. We detected 1,824 individuals of 29 species of migratory land birds, six of which were considered incidental in our study region. We modeled the abundance of the remaining 23 species, while considering observer and time of day effects on detectability. We found that both elevation and land cover had an overriding influence on the abundance of migratory species across the Andes, with strong evidence for a mid‐elevation peak in abundance, and species‐specific responses to both variables. As a community, migratory birds had the highest mean abundance in shade coffee plantations, secondary forest, and mature forest. Aboveground woody biomass did not affect the abundance of all species as a group, but a few showed strong responses to this variable. Contrary to predictions of a positive correlation between abundance and precipitation, we found no evidence for community‐level responses to precipitation, aside for a weak tendency for birds to select areas with intermediate levels of precipitation. This novel use of a multispecies model sheds new light on the mechanisms shaping the winter distribution of migratory birds and highlights the importance of elevation and land cover types over climatic variables in the context of the Colombian Andes. [ABSTRACT FROM AUTHOR]

Summary: The Canada Warbler Cardellina canadensis is a steeply declining Neotropical migratory bird and > 50% of its non-breeding range is within the Colombian Andes. Despite being an abundant migrant in Andean forests, the species' elevational distribution and non-breeding ecology have yet to be studied, thereby precluding the design of effective conservation actions. During four non-breeding periods (2012–2016), we surveyed Colombia's three Andean ranges, carrying out passive 5-minute point counts between 700 and 3,150 m asl in five habitats (mature forest, secondary growth, forest edges/riparian forest, shade coffee, sun coffee), recording the perpendicular distance, sex, foraging height, and association with mixed species flocks of Canada Warbler. Habitat variables were recorded at each point. Based on 819 passive point counts, Canada Warblers occupied elevations between 750 and 2,300 m, being more abundant between 1,000 and 2,200 m. Relative densities were higher in mature forest compared to shade coffee and secondary forest, and accordingly abundance increased with canopy height. There was no evidence for a difference in elevation or habitat use by males and females. Within forests, birds foraged at mid-levels, 5–15 m above the ground, and the probability of Canada Warblers occurring in mixed species flocks increased with elevation. Models of variation in relative density throughout the Eastern Andes showed a positive relation with cloud cover and above-ground forest biomass, implying a preference for humid, forested regions. Of the areas in the Eastern Andes with high predicted relative density, ∼ 14% overlapped with protected areas and we identify priority areas where protective measures could benefit the conservation status of the species. For maximum effectiveness, conservation actions should focus on protecting forest fragments and initiating reforestation projects at mid-elevations (1,000–2,200 m), as well as supporting agroforestry practices in humid regions of the Colombian Andes. [ABSTRACT FROM AUTHOR]

Aim: The role of migratory birds in the spread of parasites is poorly known, in part because migratory strategies and behaviours potentially affecting transmission are not easy to study. We investigated the dynamics of infection by blood parasites through the annual cycle of a long‐distance Nearctic–Neotropical migratory songbird to examine the role of this species in dispersing parasites between continents. Location: The Americas. Taxon: Grey‐cheeked Thrush (Catharus minimus, Aves, Passeriformes, Turdidae), Birds. Methods: We used molecular and microscopy screening of haemosporidian parasites (Plasmodium, Haemoproteus, and Leucocytozoon) to examine the prevalence, distribution, and diversity of lineages through the annual cycle (breeding, migration, and wintering) of the grey‐cheeked thrush in North and Central America, Santa Marta mountains, the Andes, and the Amazon. We aimed to identify transmission areas, to examine the degree of sharing of haemosporidian lineages with resident birds in various areas and to assess the potential role of immunologically naïve juvenile individuals in parasite transmission. Results: Prevalence and lineage diversity of haemosporidians varied significantly over time, being higher during breeding and fall and spring migration, and declining during wintering. Grey‐cheeked thrush shared few parasite lineages with tropical resident birds and slightly more lineages with other migratory and resident boreal species. We detected gametocytes in blood during spring migration stopover, but these were of lineages not found in resident tropical birds, indicating relapses of parasites transmitted elsewhere. Transmission likely occurs mostly on the breeding grounds, where juveniles and adults carried lineages restricted to closely related species of thrushes and other species of boreal birds. Main conclusions: Long‐distance migratory songbirds are likely not important dispersers of blood parasites because there are ecological and evolutionary barriers to the interchange of parasites across vastly separated areas. Further work with thorough spatial and temporal sampling across other species, and considering the role of vectors, is necessary to understand the ecological and evolutionary factors explaining the distribution of parasites over broad scales. [ABSTRACT FROM AUTHOR]

Nearly 300 species of landbirds, whose populations total billions, migrate between the Neotropics and North America. Many migratory populations are in steep decline, and migration is often identified as the greatest source of annual mortality. Identifying birds’ needs on migration is therefore central to designing conservation actions for Nearctic-Neotropical migratory birds; yet migration through the Neotropics is a significant knowledge gap in our understanding of the full annual cycle. Here, we synthesise current knowledge of Neotropical stopover regions and migratory bottlenecks, focusing on long-distance, migratory landbirds that spend the boreal winter in South America. We make the important distinction between “true” stopover—involving multi-day refuelling stops—and rest-roost stops lasting < 24 hours, citing a growing number of studies that show individual landbirds making long stopovers in just a few strategic areas, to accumulate large energy reserves for long-distance flights. Based on an exhaustive literature search, we found few published stopover studies from the Neotropics, but combined with recent tracking studies, they describe prolonged stopovers for multiple species in the Orinoco grasslands (Llanos), the Sierra Nevada de Santa Marta (Colombia), and the Yucatan Peninsula. Bottlenecks for diurnal migrants are well described, with the narrowing Central American geography concentrating millions of migrating raptors at several points in SE Mexico, Costa Rica, Panama and the Darién. However, diurnally migrating aerial insectivores remain understudied, and determining stopover/roost sites for this steeply declining group is a priority. Despite advances in our knowledge of migration in the Neotropics, we conclude that major knowledge gaps persist. To identify stopover sites and habitats and the threats they face, we propose a targeted and collaborative research agenda at an expanded network of Neotropical sites, within the context of regional conservation planning strategies. [ABSTRACT FROM PUBLISHER]

Copyright of Boletin SAO is the property of Sociedad Antioquena de Ornitologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)