Neotropical Birds Research Articles

Physiological underpinnings associated with differences in pace of life and metabolic rate in north temperate and neotropical birds

Animal life-history traits fall within limited ecological space with animals that have high reproductive rates having short lives, a continuum referred to as a "slow-fast" life-history axis. Animals of the same body mass at the slow end of the life-history continuum are characterized by low annual reproductive output and low mortality rate, such as is found in many tropical birds, whereas at the fast end, rates of reproduction and mortality are high, as in temperate birds. These differences in life-history traits are thought to result from trade-offs between investment in reproduction or self-maintenance as mediated by the biotic and abiotic environment. Thus, tropical and temperate birds provide a unique system to examine physiological consequences of life-history trade-offs at opposing ends of the "pace of life" spectrum. We have explored the implications of these trade-offs at several levels of physiological organization including whole-animal, organ systems, and cells. Tropical birds tend to have higher survival, slower growth, lower rates of whole-animal basal metabolic rate and peak metabolic rate, and smaller metabolically active organs compared with temperate birds. At the cellular level, primary dermal fibroblasts from tropical birds tend to have lower cellular metabolic rates and appear to be more resistant to oxidative cell stress than those of temperate birds. However, at the subcellular level, lipid peroxidation rates, a measure of the ability of lipid molecules within the cell membranes to thwart the propagation of oxidative damage, appear not to be different between tropical and temperate species. Nevertheless, lipids in mitochondrial membranes of tropical birds tend to have increased concentrations of plasmalogens (phospholipids with antioxidant properties), and decreased concentrations of cardiolipin (a complex phospholipid in the electron transport chain) compared with temperate birds.

High survival and low fecundity of a neotropical savanna tanager

Demographic factors are fundamental aspects of the population ecology of wild birds. However, they are poorly understood in endemic and threatened birds of the Neotropics. In this study we demonstrate that, as in tropical forest birds, a neotropical bird inhabiting a highly seasonal savanna has high rates of survival and low rates of fecundity. We conducted a 2.5-year mark—resighting study to determine survival, fecundity and population structure for the White-banded Tanager (Neothraupis fasciata) in a 10 547 ha protected area of the Cerrado, central Brazil's savanna. Age-structure appeared to have a stable distribution and sex-ratio was 1.2:1 (male: female). Population and effective population sizes were estimated at 6763 and 3438 birds. Density was estimated at 1.1 individual ha−1 and carrying capacity at 7440 birds. Apparent annual survival rate for adults was 68% and for juveniles 42%. Females bred successfully at 2 years old but males only bred successfully when 3 years old. Average fecundity was estimated at 0.31, being higher for adult females than for subadult females. Our results are more consistent with the pattern of higher survival and lower fecundity observed in tropical birds than the pattern observed in Nearctic birds, even though the Cerrado is a highly seasonal savanna.

Territorial system and adult dispersal in a cooperative-breeding tanager

ABSTRACT Latitudinal differences in territorial behavior are considered to have great influence on differences in life-history strategies of Nearctic and Neotropical birds. Most territorial behavior of tropical birds has particularities that cannot be explained only by theories from studies of birds in temperate regions. We evaluated the territorial system of the cooperative-breeding White-banded Tanager (Neothraupis fasciata) in central Brazil's savanna and present results on stability of territory site occupation, relationship between territory size and group size, and dispersal patterns. Territories (n = 27, mean per season) were monitored for 3 yr in a protected area in the cerrado of central Brazil and were defined by the minimum convex polygon method. Territory size averaged 3.7 ± 0.6 ha, and was defended by all individuals of groups of 2–8 individuals (mean = 3.4 ± 1.2). We recorded 44 dispersal events between territories, and most individuals dispersed distances equal to one territory in length. M...

Birds as potential pollinators of the Spathodea nilotica (Bignoniaceae) in the urban environment.

Birds play crucial role on the pollination of many plants. However, little is known about the interactions between nectarivorous neotropical birds and exotic Angiosperms. S. nilotica is an exotic African plant widely used in Brazilian urban landscaping. However, it has been poorly studied in relation to its interactions with Neotropical birds. In this way, we studied the feeding nectar strategies and the interspecific antagonistic behaviours among nectarivorous Neotropical birds to verify the bird contributions to the S. nilotica pollination. The study was conducted from May 2008 to April 2011, but only in months of S. nilotica flowering (April to May). From 148 hours of sampling we identified 16 species feeding nectar on S. nilotica: 13 hummingbirds (Trochilidae), Aratinga aurea (Psittacidae), Tangara palmarum (Thraupidae) and Coereba flaveola (Coerebidae). Eupetomena macroura was the most frequent (96.88%), followed by Chlorostilbon lucidus (78.13%) and Coereba flaveola (59.38%). Most birds obtained nectar by punching at the base of the corolla, except for A. aurea that obtained the nectar by the upper opening of the petals in 100% of its visits, Heliomaster furcifer (95.65%), F. fusca (95%) and A. nigricollis (70.27%). Despite E. macroura also obtains nectar only by punching at the base of the corolla, it showed the highest level of legitimate visits. Antagonistic events were more frequent in E. macroura (58.65%), Florisuga fusca (11.04%) and Amazilia fimbriata (10.87%), being E. macroura dominant in all events. These results showed E. macroura plays an important role on this plant being the most important bird as a potential pollinator. Moreover, other birds contribute partially to the S. nilotica pollination. Most probably it is a result of recent Neotropical bird interactions with this African plant.

Diet of the Fuscous Flycatcher Cnemotriccus fuscatus (Wied, 1831) - Aves, Tyrannidae - in three habitats of the northern Pantanal, Mato Grosso, Brazil.

The Fuscous Flycatcher (Cnemotriccus fuscatus) is a medium-sized Tyrannidae widespread in South America. Despite its large distribution, there have been very few studies on its diet, especially in different habitats. This study presents data on diet variation in three habitats in the Pantanal wetlands in the state of Mato Grosso, Brazil. The specimens were captured through a mist-netting programme between February 2000 and May 2010, in the Retiro Novo Farm, in the Poconé municipality. Birds were captured in three vegetation types: Landizal, Cambarazal and Cordilheira. Tartar emetic was used to obtain the regurgitation samples identified at order level. We captured 61 individuals (21, 26 and 14 in the above described habitats, respectively). Diet of C. fuscatus differed between the three habitats. Ants and beetles were the most relevant prey items either in numerical frequency (NF) or in frequency of occurrence (OF), in terms of the overall diet (NF = 27.34% and 37.89%; OF = 36.06% and 75.4%, respectively). However, in Cordilheira, seeds and beetles dominated the NF (21.8% and 38.1%, respectively) and OF (28.5% and 85.7%, respectively). Cnemotriccus fuscatus was found to have an omnivorous diet, although in Cambarazal, individuals preyed exclusively on arthropods. The present study provides an important contribution to the knowledge of the diet of a poorly studied Neotropical bird.

Multilocus analysis of intraspecific differentiation in three endemic bird species from the northern Neotropical dry forest

Among-species phylogeographic concordance provides insight into the common processes driving lineage divergence in a particular region. However, identifying the processes that caused phylogeographic breaks is not always straight forward, and inferring past environmental conditions in combination with documented geologic events is sometimes necessary to explain current patterns. We searched for concordant phylogeographic patterns and investigated their causes in three bird species (Momotus mexicanus, Melanerpes chrysogenys, and Passerina leclancherii) that belong to three different avian orders and are endemic to the northernmost range of the Neotropical dry forest. We obtained mitochondrial DNA (ND2 and COI or cyt b) and nuclear DNA (20454, GAPDH, MUSK, and TGFB) sequences for at least one locus from 162 individuals across all species and defined climatically stable areas using environmental niche model projections for the last 130,000years to have a paleoenvironmental framework for the phylogeographic results. All three species showed marked phylogeographic structure, with breaks found in roughly similar areas, such as the border between the Mexican states of Guerrero and Oaxaca, and between southern Jalisco and Michoacán. Both of these regions are known biogeographic breaks among other taxa. Patterns of genetic diversity and differentiation were partially compatible with climatically stable areas. Coalescent analyses revealed recent population growth and estimated the deeper haplogroup divergence of all three taxa to have occurred within the last 600,000years. The phylogeographic patterns found are noteworthy because they are maintained in a relatively small area for bird species with continuous ranges, and highlight a unique situation when compared to phylogeographic patterns found in other studies of Neotropical birds that have stressed the role of geographic barriers to explain intraspecific differentiation. Our results point to a scenario of population isolation resulting in the present phylogeographic structure, likely a result of historical climate fluctuations that have fragmented and reconnected the Neotropical dry forest. This study contributes to a growing body of evidence indicating active diversification of endemic lineages in the northern Neotropical dry forest region.

Coffee Agroforests Remain Beneficial for Neotropical Bird Community Conservation across Seasons

Coffee agroforestry systems and secondary forests have been shown to support similar bird communities but comparing these habitat types are challenged by potential biases due to differences in detectability between habitats. Furthermore, seasonal dynamics may influence bird communities differently in different habitat types and therefore seasonal effects should be considered in comparisons. To address these issues, we incorporated seasonal effects and factors potentially affecting bird detectability into models to compare avian community composition and dynamics between coffee agroforests and secondary forest fragments. In particular, we modeled community composition and community dynamics of bird functional groups based on habitat type (coffee agroforest vs. secondary forest) and season while accounting for variation in capture probability (i.e. detectability). The models we used estimated capture probability to be similar between habitat types for each dietary guild, but omnivores had a lower capture probability than frugivores and insectivores. Although apparent species richness was higher in coffee agroforest than secondary forest, model results indicated that omnivores and insectivores were more common in secondary forest when accounting for heterogeneity in capture probability. Our results largely support the notion that shade-coffee can serve as a surrogate habitat for secondary forest with respect to avian communities. Small coffee agroforests embedded within the typical tropical countryside matrix of secondary forest patches and small-scale agriculture, therefore, may host avian communities that resemble those of surrounding secondary forest, and may serve as viable corridors linking patches of forest within these landscapes. This information is an important step toward effective landscape-scale conservation in Neotropical agricultural landscapes.

Specialization on Bamboo by Neotropical Birds

Fil: Cockle, Kristina Louise. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Salta. Instituto de Bio y Geociencias del Noroeste Argentino; Argentina. Universidad del Estado de Luisiana. Facultad de Recursos Naturales Renovables; Estados Unidos

Neotropical birds of prey: biology and ecology of a forest raptor community

Neotropical birds of prey: biology and ecology of a forest raptor community

Neotropical Birds of Prey: Biology and Ecology of a Forest Raptor Community edited by David F. Whitacre

Neotropical Birds of Prey: Biology and Ecology of a Forest Raptor Community edited by David F. Whitacre

Stepwise colonization of the Andes by Ruddy Ducks and the evolution of novel β‐globin variants

Andean uplift played a key role in Neotropical bird diversification, yet past dispersal and genetic adaptation to high-altitude environments remain little understood. Here we use multilocus population genetics to study population history and historical demographic processes in the ruddy duck (Oxyura jamaicensis), a stiff-tailed diving duck comprising three subspecies distributed from Canada to Tierra del Fuego and inhabiting wetlands from sea level to 4500 m in the Andes. We sequenced the mitochondrial DNA, four autosomal introns and three haemoglobin genes (α(A), α(D), β(A)) and used isolation-with-migration (IM) models to study gene flow between North America and South America, and between the tropical and southern Andes. Our analyses indicated that ruddy ducks dispersed first from North America to the tropical Andes, then from the tropical Andes to the southern Andes. While no nonsynonymous substitutions were found in either α globin gene, three amino acid substitutions were observed in the β(A) globin. Based on phylogenetic reconstruction and power analysis, the first β(A) substitution, found in all Andean individuals, was acquired when ruddy ducks dispersed from low altitude in North America to high altitude in the tropical Andes, whereas the two additional substitutions occurred more recently, when ruddy ducks dispersed from high altitude in the tropical Andes to low altitude in the southern Andes. This stepwise colonization pattern accompanied by polarized β(A) globin amino acid replacements suggest that ruddy ducks first acclimatized or adapted to the Andean highlands and then again to the lowlands. In addition, ruddy ducks colonized the Andean highlands via a less common route as compared to other waterbird species that colonized the Andes northwards from the southern cone of South America.

Philornis sp. bot fly larvae in free living scarlet macaw nestlings and a new technique for their extraction

Bot fly larvae (Philornis genus) are obligate subcutaneous blood-feeding parasites of Neotropical birds including psittacines. We analyze twelve years of data on scarlet macaw (Ara macao) nestlings in natural and artificial nests in the lowland forests of southeastern Peru and report prevalence and intensity of Philornis parasitism. Bot fly prevalence was 28.9% while mean intensity was 5.0 larvae per infected chick. Prevalence in natural nests (11%, N=90 nestlings) was lower than in wooden nest-boxes (39%, N=57) and PVC boxes (39%, N=109). We describe a new technique of removing Philornis larvae using a reverse syringe design snake bite extractor. We compare this new technique to two other methods for removing bots from macaw chicks and find the new method the most suitable.

Recommendations for monitoring avian populations with point counts: a case study in southeastern Brazil

In the northern hemisphere, bird counts have been fundamental in gathering data to understand population trends. Due to the seasonality of the northern hemisphere, counts take place during two clearly defined moments in time: the breeding season (resident birds) and winter (after migration). Depending on location, Neotropical birds may breed at any time of year, may or may not migrate, and those patterns are not necessarily synchronous among species. Also in contrast to the northern hemisphere, population trends and the impact of rapid urbanization and deforestation are unknown and unmonitored. Throughout one year, we used point counts to better understand temporal patterns of bird species richness and relative abundance in the state of São Paulo, southeastern Brazil, to examine how to implement similar bird counts in tropical America. We counted birds twice each day on 10 point transects (20 points day‑1), separated by 200 m, with a 100 m limited detection radius in a semideciduous tropical forest. Both species richness and bird abundance were greater in the morning, but accumulation curves suggest that longer-duration afternoon counts would reach the same total species as in morning counts. Species richness and bird abundance did not vary seasonally and unique species were counted every month; relatively few species (20%) were present in all months. Most (84%) known forest species in the area were encountered. We suggest that point counts can work here as they do in the northern hemisphere. We recommend that transects include at least 20 points and that the simplest timing of bird counts would also be seasonal, using timing of migration of austral migrants (and six months later) to coordinate counts. We propose that bird counts in Brazil, and elsewhere in Latin America, would provide data to help understand population trends, but would require greater effort than in temperate latitudes due to greater species richness and different dynamics of reproduction and migration. With collaboration among ornithologists and coordinated bird surveys, we may develop a technique for the tropics that would yield information for population trends and conservation of birds, similar to counts in temperate latitudes.

Breeding Biology Research and Data Availability for New World Flycatchers

Life-history strategies of Neotropical birds differ markedly from their Nearctic counterparts, yet the lack of detailed information on most Neotropical species hinders meaningful comparisons. We performed a gap analysis with several basic life-history traits of New World flycatchers of the subfamily Fluvicolinae. We found breeding data mostly on clutch sizes and linear egg measurements in 303 publications spanning the years 1838 to 2012. Data from the USA and Argentina were more abundant, with the number of publications per country being significantly and positively related to human development index (HDI) and Fluvicolinae breeding species richness. The amount of available clutch size information for each species was positively related to species’ range size and relative abundance. More research is needed concerning narrowly distributed and uncommon species. Additional efforts to gather data on all Neotropical species are, however, crucial for future advancements.

Identifying biases at different spatial and temporal scales of diversification: a case study in the Neotropical parrotlet genus Forpus

The temporal origins of the extraordinary biodiversity of the Neotropical region are highly debated. Recent empirical work has found support for alternative models on the tempo of speciation in Neotropical species further fuelling the debate. However, relationships within many Neotropical lineages are poorly understood, and it is unclear how this uncertainty impacts inferences on the evolution of taxa in the region. We examined the robustness of diversification patterns in the avian genus Forpus by testing whether the use of different units of biodiversity (i.e. biological species and statistically inferred species) impacted diversification rates and inferences regarding important biogeographic breaks in the genus. We found that the best-fit model of diversification for the biological species data set was a declining rate of diversification; whereas a model of constant diversification was the best-fit model for statistically inferred species or subspecies. Moreover, the relative importance of different landscape features in delimiting genetic structure across the landscape varied across data sets with differing units of biodiversity. Patterns based on divergence times among biological species indicated old speciation events across major geographic and river barriers. In contrast, data sets more inclusive of the diversity in Forpus illustrate the role of both old divergence across major landscape features and more recent divergences that are possibly attributed to Pleistocene climatic changes. Overall, these results indicate that conflicting models on the temporal origins of Neotropical birds may be attributable to sampling biases.

Assessing the effects of selective logging on birds in Neotropical piedmont and cloud montane forests

In tropical and subtropical forests there is limited information about how to integrate sustainable timber management with the conservation of biodiversity. We examined the effect of selective logging on the bird community to help develop management guidelines to assure the conservation of biodiversity in forests managed for timber production. The study design consisted of control and harvested plots in piedmont and cloud forests of the subtropical montane forests of the Andes in northwestern Argentina. We conducted bird point-count surveys combined with distance estimation. Breeding season bird community composition was more similar between control and logged forest in both the cloud forest and piedmont, than between the two elevations, probably because Neotropical bird communities change dramatically along elevational gradients. Within each elevation zone, community composition changed significantly between harvested and control forests. Both between and within each elevation zone no significant differences in bird density were detected. Similarly, when we analyzed bird density according to diet guilds no general pattern could be extracted. However, we found a significantly greater density of cavity nesters and lower of non-cavity nesters in control plots, probably because most trees that can develop suitable cavities were extracted in logged plots and these plots had a greater structural diversity enabling more nesting resources. Grouping species according to their nesting habitat requirements has rarely been used in the neotropics and other tropical and subtropical forests, but focusing management attention on cavity nesters might address the most sensitive portion of the avian community as well as other species dependent on trees likely to hold cavities.

Nest attentiveness in several Neotropical suboscine passerine birds with long incubation periods

Many species of tropical birds have prolonged incubation periods compared to other tropical species and to most species in temperate latitudes. One hypothesis for prolonged incubation is that these tropical species reduce nest attendance to minimize the risk of predation. The resulting decrease in average egg temperature would reduce embryo growth rate and lengthen the embryo development period. We sampled six species of Neotropical, lowland, inner forest antbirds (Thamnophilidae) and flycatchers (Tyrannidae) with average incubation periods between 17.9 and 23.3 days. Estimated total integrated 24-h nest attendance between clutch completion and hatching ranged between 14.2 and 19.5 days, representing 71–84 % of the incubation periods. Because total nest attendance in these species exceeded the incubation periods of most small passerine birds in temperate latitudes, and because average nest attendance per day did not differ substantially between these tropical species and temperate species, reduced nest attendance does not appear to cause their prolonged incubation periods. Instead, these extended egg periods likely reflect slower embryonic growth and development at a given egg temperature. Prolonged incubation can increase time-dependent mortality in the nest, which would require an increase in either post-fledging survival or adult reproductive success to favor a slow-growth evolutionary strategy. Mechanisms underlying the postulated trade-off between incubation period length and individual quality merit further investigation.

Testing the microclimate hypothesis: Light environment and population trends of Neotropical birds

Species vary in their vulnerability to extirpation or extinction in response to habitat loss, including deforestation. A variety of correlates of vulnerability have been found, but few empirical data have been gathered that provide insight into potential causation. We attempted to elucidate cause via a test of the “microclimate hypothesis” at two sites in the northern Neotropics. We censussed birds at 234 points that varied in distance from a deforested edge to >2km into a forest. At each of these points we recorded or calculated ten environmental and microclimate variables that allowed us to tie environmental data to bird assemblages directly. We found that canopy cover increased, wind decreased, and ambient temperature, vapor pressure density, and heat index varied little or not at all with distance from a forested edge. Yet light penetration was the key variable, as the light environment was affected within 50m of an edge, and many species were associated with low-light conditions. Crucially, on the basis of regional population trends, species in low-light environments are more vulnerable to extirpation. Our results provide the clearest support to date of the hypothesis that sensitivity to light is a key factor limiting occupancy of birds in fragmented tropical forests and lend support to at least this aspect of the microclimate hypothesis.

Inferring the origins of lowland Neotropical birds

Inferring the origins of lowland Neotropical birds

Survival of resident Neotropical birds: Considerations for sampling and analysis based on 20 years of bird-banding efforts in Mexico

Long-term bird-banding programs provide knowledge of the demographic rates of avian populations, but we currently lack information on demographic rates of most bird populations in species-rich tropical ecosystems. Banding in tropical regions is typically conducted with protracted or irregular sampling occasions that make the choice of the proper capture—mark—recapture (CMR) model difficult. Here, we address common challenges related to collecting and analyzing data to estimate survival rates of resident Neotropical birds using 20 years of banding efforts in Mexico as a case study. We applied Cormack-Jolly-Seber and Barker models to estimate apparent survival and recapture probabilities of species with sufficient data for survival analyses. We were able to analyze 6 resident species of 136 total species; apparent survival probabilities ranged from 0.30 to 0.77, and recapture probabilities from 0.11 to 0.52. For monitoring programs with existing data collected at continuous, uneven, or irregular intervals, we recommend the application of the Barker model over other models because it was more efficient in the use of available banding data and less often violated CMR assumptions. We recommend that monitoring programs last >10 years and provide additional protocol suggestions for primary and secondary sampling occasions, as well as the number of nets, potential net configurations, and the extent of the spatial scale. These baseline recommendations are likely to foster an increase in our knowledge of avian survival rates in tropical ecosystems, which is imperative for managing tropical bird populations under changing environmental conditions.