Leonardo Esteves Lopes

Geographic and seasonal distribution of the Cock-tailed Tyrant (Alectrurus tricolor) inferred from niche modeling

AbstractThe Cock-tailed Tyrant (Alectrurus tricolor) is a habitat-sensitive and vulnerable bird found in South American grasslands. It is assumed to be migratory but no detailed analysis of distributional records per season has been made. Because of a limited number of field records, we used niche-modeling tools to predict the geographic distribution of the Cock-tailed Tyrant with three objectives: identifying its breeding (summer) and non-breeding (winter) grounds based on climatic suitability, test the hypothesis that it migrates, and test the assumption that it is a niche tracker. The species is apparently not migratory since there was an equivalency of the breeding and winter niches and we found no pattern of latitudinal or altitudinal migration. However, the species seems to be a climatic niche switcher since breeding and winter estimated distributions are not good predictors of the other season’s occurrences. We conclude that the Cock-tailed Tyrant is probably resident throughout its range, and that the reported apparent migratory behavior probably reflects partial population migration, seasonal changes in social behavior, or even nomadism. Long-term year-round population studies are warranted.ZusammenfassungGeografische und jahreszeitliche Verbreitung des Hahnenschwanztyranns (Alectrurus tricolor) anhand von ökologischer Nischenmodellierung Der Hahnenschwanztyrann (Alectrurus tricolor) ist eine habitatsensitive und gefährdete Vogelart des südamerikanischen Graslandes. Allgemein gilt er als Zugvogel, allerdings wurde bisher noch keine detaillierte jahreszeitliche Analyse der Verbreitungsnachweise durchgeführt. Aufgrund der begrenzten Anzahl von Freilandnachweisen verwendeten wir Methoden der ökologischen Nischenmodellierung zur Vorhersage der geografischen Verbreitung des Hahnenschwanztyranns. Dabei verfolgten wir drei Ziele: Ermittlung der Brut- und Winterverbreitung auf der Grundlage geeigneter klimatischer Rahmenbedingungen, Überprüfung der Zugvogel-Hypothese sowie Überprüfung der Annahme, dass der Hahnenschwanztyrann ein Nischenverfolger ist. Die Art ist offenbar kein Zugvogel, da sich ihre ökologischen Nischen zur Brutzeit und im Winter entsprechen und wir kein Muster von breiten- oder höhenbedingten Wanderungen feststellen konnten. Allerdings scheint die Art die klimatische Nische zu wechseln, da die geschätzte Brutverbreitung hier keine guten Voraussagen für die geschätzte Winterverbreitung ergibt und umgekehrt. Unsere Schlussfolgerungen lauten, dass der Hahnenschwanztyrann vermutlich in seinem gesamten Verbreitungsgebiet ein Standvogel ist. Berichte über sein scheinbares Zugverhalten spiegeln möglicherweise Wanderungen von Teilpopulationen, jahreszeitliche Veränderungen des Sozialverhaltens oder sogar Nomadismus wider. Zur weiteren Aufklärung wären langfristige ganzjährige Populationsstudien erforderlich.

Soil attributes drive nest-site selection by the campo miner Geositta poeciloptera

Substrate type is a key-factor in nest-site selection and nest architecture of burrowing birds. However, little is known about which factors drive nest-site selection for these species, especially in the tropics. We studied the influence of soil attributes on nest-site selection by the campo miner Geositta poeciloptera, an open grassland bird that builds its nests within soil cavities. For all nests found, we measured the depth of the nest cavity and the resistance of the soil to penetration, and identified the soil horizon in which the nest was located. In soil banks with nests, we collected soil samples for granulometric analysis around each nest cavity, while in soil banks without nests we collected these samples at random points. From 43 nests found, 86% were located in the deeper soil horizons (C-horizon), and only 14% in the shallower horizons (B-horizon). Granulometric analysis showed that the C-horizons possessed a high similar granulometric composition, with high silt and low clay contents. These characteristics are associated with a low degree of structural development of the soil, which makes it easier to excavate. Contrarily, soil resistance to penetration does not seem to be an important criterion for nest site selection, although nests in more resistant the soils tend to have shallower nest cavities. Among the soil banks analyzed, 40% of those without cavities possessed a larger proportion of B-horizon relative to the C-horizon, and their texture was more clayey. On the other hand, almost all soil banks containing nest cavities had a larger C-horizon and a silty texture, indicating that soil attributes drive nest-site selection by G. poeciloptera. Thus, we conclude that the patchy distribution of G. poeciloptera can attributed to the infrequent natural exposure of the C-horizon in the tropical region, where well developed, deep and permeable soils are more common.

Natural history of the Lined Seedeater Sporophila lineola (Aves: Thraupidae) in southeastern Brazil

ABSTRACT The Lined Seedeater (Sporophila lineola) is a migratory species that inhabits a variety of open habitats in South America. We studied the breeding biology and territorial behaviour of a colour-banded population of the species in the Universidade Federal de Viçosa, Campus Florestal (1–19,8808ºS, –44,4136ºW), during two breeding seasons (2014/2015 and 2015/2016), which spans from December to April. We monitored 74 nests of this species. The nest is a low cup supported between a fork. Nests are mainly built with grass stems and rootlets, with spider-web used to hold the material together and to bind the nest to its supporting plant. Females are solely responsible for nest building and incubation, which is synchronic, and also for feeding nestlings to a large extent. Males are responsible for defending the territory, which corresponds to a small portion of the home range restricted to the nest environs, and also feed the nestlings. Mean clutch size is two eggs (78% of nests monitored), with clutches of three (20.3%) and four (1.7%) eggs also observed. Eggs are whitish, covered with dark brown blotches and spots to a variable extent. Mean incubation period, considered as the period between the onset of incubation and hatching of the first egg, is 11 days. Nestling period, considered as the period between hatching of the first egg and fledging of the last young, is 10 days. During the first breeding season, the simple percentage of successful nests was 34.1%, while the Mayfield success was 29.8%, with slightly higher values observed during the second breeding season, with 39.4% and 35.7%, respectively. We recorded, for the first time, three cases of polygamy in the species. We also recorded breeding site fidelity for the first time in the species, with males returning to the same territory owned in a previous breeding season.

Breeding biology of the Pale-bellied Tyrant-manakin Neopelma pallescens (Aves: Pipridae) in south-eastern Brazil

ABSTRACT The Pale-bellied Tyrant-manakin (Neopelma pallescens) inhabits semi-deciduous and riparian forests in central-north South America. Contrary to most manakins, there is no evident sexual dichromatism in the species and little is known about its breeding biology. We studied the breeding biology of a colour-banded population of the species from August to December 2016 and from August to October 2017 in the Campus Florestal of the Universidade Federal de Viçosa, south-eastern Brazil. The breeding season extended from early September to late November. The species is promiscuous, with males exhibiting simple courtship displays (exploded leks) in individual arenas. The nest (n = 13) is a cup attached by its top lip between forked branches and is very simple, with a structural layer made with dry grass stems and heads, attached to the branch with spider silk. The outer and lining layers are absent. The mean clutch size was 1.8 eggs (n = 11), which are oval and pale coloured, covered with spots of different shades of brown, often concentrated in the larger pole. Mean egg length and width (± SD) were 21.0 ± 0.9 × 15.8 ± 0.7 mm (n = 14) and the mean weight was 2.8 ± 0.4 g (n = 10). The incubation period could not be estimated, but the nestling period was 15 days (n = 2). The simple percentage of successful nests was 15.4%, with 76.9% of the nests depredated and 7.7% abandoned. This is the first detailed study about the breeding biology of any Neopelma species, providing relevant data for the study of the evolution of life history strategies not only for the genus, but for the whole family Pipridae.

Variation of plumage patterns, geographic distribution and taxonomy of the Unicolored Blackbird (Aves: Icteridae)

The Unicolored Blackbird Agelasticus cyanopus (Vieillot, 1819) is a marsh bird with four allopatric subspecies restricted to lowlands in South America east of the Andes. I conducted a taxonomic revision of the species based on analysis of external morphological characters of 288 study skins, including all types available. My revision shows that: 1) Leistes unicolor Swainson, 1838, is a senior synonym of A. c. xenicus (Parkes, 1966) and, therefore, the correct name of the taxon should be A. c. unicolor (Swainson, 1838); 2) the range of A. c. unicolor (Swainson, 1838) is much wider than previously thought, extending from the mouth of the Rio Amazonas to the state of São Paulo, in southeastern Brazil, where it intergrades with A. c. atroolivaceus (zu Wied-Neuwied, 1831); 3) A. c. atroolivaceus extends its range well beyond the coast of Rio de Janeiro, reaching the coast of São Paulo, the central part of Minas Gerais, Bahia and Espírito Santo; and 4) specimens attributed to A. c. beniensis are highly variable, so this name must be considered a subjective junior synonym of the nominotypical taxon. Under the Biological Species Concept, two broadly parapatric species should be recognized, A. cyanopus and A. atroolivaceus (including unicolor as a subspecies). Under the Phylogenetic Species Concept or the General Lineage Concept of Species, the best taxonomic treatment is to recognize three species: A. cyanopus, A. atroolivaceus, and A. unicolor.

Morphological variation of the Long-tailed Reed Finch Donacospiza albifrons (Vieillot, 1817) (Aves: Thraupidae)

The Long-tailed Reed Finch Donacospiza albifrons of south-central South America is patchily distributed in a variety of open habitats, usually near water. I present a detailed study of morphological variation based on 141 specimens, describing its plumage sequence and presenting notes on its molt and breeding. The Long-tailed Reed Finch shows no sexual dichromatism, but males average longer-winged than females. The species shows three distinct age-related plumages, which are redescribed here. It also shows marked individual variation in plumage and size, also showing marked plumage variation due to feather wear. Geographic variation is also marked, with birds from dry grasslands in northern highlands typically being larger, paler, and less streaked than birds from wet grasslands in southern lowlands, but there at some exceptions to this geographic pattern. I conclude that there is no solid basis for splitting the species into two or more taxa, and suggest considering the Long-tailed Reed Finch as a single, highly polymorphic species.

Breeding biology of the threatened Campo Miner Geositta poeciloptera (Aves: Scleruridae), a Neotropical grassland specialist

ABSTRACT The Campo Miner is a threatened grassland passerine endemic to the South American Cerrado, whose life history is almost unknown. In this paper, we studied during three breeding seasons (2014 to 2016) the breeding biology of a colour banded population of the species found in the Upper Rio Grande Grasslands, south-eastern Brazil. We found 98 nests, 81 of which became active and were monitored. The Campo Miner breeds in frequently burnt-and-grazed natural grasslands, successfully nesting in highly disturbed sites, such as dirt banks along roads and even in mine pits. The species is socially monogamous and both parents build the nest, which is a cavity/with-tunnel/simple/platform type. The nest chamber is lined with a platform made of grass fragments, charcoal, hairs, and mammal faeces. The most common clutch size is three eggs (n = 66), with some nests containing one (n = 1), two (n = 12) or four eggs (n = 2). The egg is white and pyriform and the incubation, performed by both parents, lasts 17.5 days. Mean nestling period is 15.5 days, with both parents feeding the young. Breeding season lasted for about 125 days (August to December) and multiple breeding attempts in a single season were common, with a maximum of three attempts recorded. All species of Scleruridae built their nests inside cavities dug in the soil with an access tunnel to it, where they lay a small clutch (usually 2–3 white eggs), but no other species in the family has been studied in detail to date. Further studies are required to understand why a species apparently tolerant to anthropogenic impacts such as G. poeciloptera can be so rare, patchily distributed and threatened throughout its range.

Melanopareia bitorquata (d'Orbigny & Lafresnaye, 1837) is a distinct species: an appraisal of morphological variation in the Collared Crescentchest Melanopareia torquata (zu Wied-Neuwied, 1831) (Aves: Melanopareiidae)

The Collared Crescentchest Melanopareia torquata is a poorly known and inconspicuous species of open savannas and grasslands in central Brazil, Paraguay and Bolivia. Three subspecies are currently recognized, but their taxonomic limits, ranges and conservation status are far from well-established. This paper analyses individual and geographic variation in this species on the basis of body measurements and plumage coloration of 119 specimens. A clinal pattern of body size variation and considerable mensural overlap precludes a clear-cut separation between the two subspecies restricted to Brazil, and there is evidently sexual dichromatism in some Brazilian populations. However, M. t. bitorquata shows highly distinct plumage features in parapatry with other forms, strongly suggesting it should be treated as a full species.

Morphological data support the recognition of four species in the genus Sirystes Cabanis & Heine, 1859 (Aves: Tyrannidae).

Sirystes is a widespread genus in the Neotropical region. Historically, five subspecies were recognized in a single widespread species, but more recently four separate species have been recognized, based on vocalizations and limited morphological data. In this paper, we analyze individual and geographic variation in this genus on the basis of body measurements and plumage coloration of 514 specimens, including all name-bearing types available. We conclude that the four recently proposed species, S. sibilator, S. albogriseus, S. albocinereus, and S. subcanescens, can also be diagnosed by morphological data, corroborating more recent taxonomic treatments. We identified possible hybrids between S. sibilator and S. albocinereus from a narrow zone of contact in central Bolivia. We show that Sirystes sibilator atimastus Oberholser, 1902 represents a point on a cline within S. sibilator (Vieillot, 1818), and it is here regarded as a subjective junior synonym of the latter. We also provide new observations on the range and diagnosis of S. subcanescens, a name that has been frequently misused, and present a redescription of the four recognized species, as well as reviewing their range and natural history.

Taxonomy, distribution, natural history and conservation of the Russet-mantled Foliage-gleaner Syndactyla dimidiata (Pelzeln, 1859) (Aves: Furnariidae)

Russet-mantled Foliage-gleaner is an extremely poorly known species, the range of which is centered in the Brazilian Cerrado, where it inhabits riparian forests. Two subspecies are recognized, but the limits of their ranges are controversial. Furthermore, it was recently suggested that the species is one of the few in the family Furnariidae to show sexual dichromatism. In this paper we examined the plumage coloration and morphometrics of 33 study skins (85% of the available specimens). We conclude that the geographic variation and sexual dichromatism reported for S. dimidiata originated from misinterpretation of the plumage variation observed in this species, which is best considered monotypic. We also present natural history data on Russet-mantled Foliage-gleaners and suggest considering it a globally Vulnerable species.