Charles Duca

Territory size of three Antbirds (Aves, Passeriformes) in an Atlantic Forest fragment in southeastern Brazil

Territory size is an important ecological attribute of populations that has been considered a factor determines population density. Antbirds is a large group of mainly insectivorous Neotropical passerines, usually well represented in bird communities from forested landscapes in Neotropical region. Territory sizes for three Antbirds, Thamnophilus caerulescens (Vieillot, 1816) (Variable Antshrike), Dysithamnus mentalis (Temmink, 1823) (Plain Antvireo) e Pyriglena leucoptera (Vieillot, 1818) (White-shouldered Fire-eye), were mapped and their area estimated by the convex polygon method in a 50 ha forest fragment, in southeastern Brazil. The three species presented small territories of similar sizes ( T. caerulescens > D. mentalis). We failed to find any effect on territory size for the three species associated with forest edge or distance to the dirt road.

Variation in Breeding of the Shrike-like Tanager in Central Brazil

Abstract The Shrike-like Tanager (Neothraupis fasciata) is a Cerrado bird considered as near threatened. Its life history is poorly known, especially its reproduction. We monitored reproduction during four breeding seasons (2003–2006) with 120 nests in a protected area in central Brazil. Nesting began at the end of the dry season and start of the rainy season. The incubation (13.0 days) and nestling (11.7 days) periods were shorter than for most neotropical birds, but similar to some other tanagers. Clutch size (2–3 eggs) was similar to most tropical birds. However, clutch size increased and nest initiation date advanced ∼30 days in a year of early precipitation compared to 3 other years with regular or late precipitation. The Shrike-like Tanager had breeding flexibility and ability to adapt to changes in temporal precipitation patterns.

Temporal variation in the reproductive success of Cacicus haemorrhous (Linnaeus) (Aves, Icterinae) in an Atlantic Forest reserve in Southeast Brazil

For colonial bird species, egg hatching synchrony has been considered an important factor in their reproductive success. The Red-rumped Cacique, Cacicus haemorrhous (Linnaeus, 1766), is a Passeriformes species (Icterinae) that reproduces in colonies in which groups of females lay their eggs at different periods during the reproductive season. The objective of this study was to evaluate if there was a variation in the reproductive success among C. haemorrhous females groups that lay eggs in different periods along the reproductive season. A total of 192 nests from four colonies were monitored at Parque Estadual do Rio Doce, Minas Gerais state, Brazil, and used to calculate the nest survival probability in different periods (early and late) of the 2001 reproductive season. The results showed that females that reproduced at the beginning of the reproductive period had higher reproductive success than those that reproduced later. Predation was the main cause of nests loss (48,4%), and an increase in predation rate was observed as the reproductive period advanced.

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 Brazils 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. Males tended to stay in the same territory, whereas females dispersed. Our results support hypotheses that predict year-long territory defense for tropical birds. Territory size reflected group size, corroborating the hypothesis that individuals adjust the territory size to ensure the amount of resources for survival.

Breeding success of Cacicus haemorrhous (Linnaeus) (Aves: Icteridae) in different environments in an Atlantic Forest reserve in Southeast Brazil

Several factors, including the site where the colony was established and number of active nests can influence directly or indirectly the breeding success of colonial birds. The red-rumped cacique, Cacicus haemorrhous (Linnaeus, 1766), is a passerine (Icteridae) that breeds in colonies in different environments. The objective of this study was to evaluate the breeding success of red-rumped cacique in relation to three environments (lake edge, forest and swamp) in which colonies were established in an Atlantic Forest reserve in southeast Brazil. Seven colonies from the three environments were monitored during the breeding season of 2001. Overall probability of nest survival was 40.5%. We found that colonies established in the swamp presented higher nest survival than the others and the ones in the lake edge had lower survival. Nest predation was the most important cause of nest failure, representing 46.5% of all nest losses. Other failure causes were abandonment and fall of nests, representing 6.6% and 6.1% of the losses, respectively. Red-rumped cacique had higher success breeding in colonies located in the swamp.

Territoriality of Six Thamnophilidae Species In A Cloud Forest In Southeastern Brazil

ABSTRACT Territorial systems of Neotropical birds remain poorly understood, especially considering the effect of interspecific interactions. Studies on territorial behavior provide information about demography and life history, and are useful for the refinement of conservation strategies. We assessed territories of six species of antbirds (Thamnophilidae) from August 2010 to May 2011 at Pedra Azul State Park, a protected area in southeastern Brazil, in a 30-ha sampling grid. Birds were captured, marked, and followed through the study area. Territory sizes of Plain Antvireo (Dysithamnus mentalis), Ferruginous Antbird (Drymophila ferruginea), Ochre-rumped Antbird (Drymophila ochropyga), White-bibbed Antbird (Myrmeciza loricata), White-shouldered Fire-eye (Pyriglena leucoptera), and Variable Antshrike (Thamnophilus caerulescens) were estimated by the convex polygon method. We found 46 territories of the six species. We compared and evaluated the effect of body size on territories among the species. Males and females were active in territory defense by emitting songs and calls. The mean territory sizes defended by the six species varied from 0.72–1.18 ha. We found empty spaces between territories and a high overlap rate among territories of different species, but no overlap within species. Thamnophilus caerulescens had the highest density and D. mentalis and D. ferruginea had lower densities. Body mass and distance to the forest edge had no effect on territory size. The territory assessment provided a precise density estimation of individuals in the study area.

High survival and low fecundity of a neotropical savanna tanager

Abstract 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 Brazils 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.

Cost of territorial maintenance by Parodon nasus (Osteichthyes: Parodontidae) in a Neotropical stream

The combined demand over a certain resource may exceed its immediate supply, which can then lead to competition between individuals. This competition may result in territorial behavior. In this study we determine the density and spatial distribution, describe the interactions arising from territorial behavior and evaluate the costs of keeping the territories defended by adults of Parodon nasus. The study was conducted in Camarinha Stream located in the Serra das Araras Ecological Station, Porto Estrela, State of Mato Grosso, Brazil. The density was constant throughout the length of the stream, with a mean (± standard deviation) of 1.01 ind./m 2 (± 0.14). Our results show that the spatial distribution of individuals in the area ranged between uniform and random. The territories were defended more often against intraspecific than interspecific intruders. The time that the owners of the territories devoted to defending them was not influenced by the size of the territories. However, owners of larger territories spent more time foraging than owners of smaller territories. As a result, owners of larger territories had less time to rest than owners of smaller territories. The results of this study show behavioral patterns relevant to understanding the relationship between size and territorial maintenance cost of P. nasus and other species of fish with territorial behavior. A demanda combinada por um recurso pode exceder a sua oferta imediata, levando os individuos a competirem. Essa competicao pode resultar no comportamento de territorialidade. Neste trabalho nos determinamos a densidade e a distribuicao espacial, descrevemos as interacoes decorrentes do comportamento territorial e avaliamos os custos de manutencao dos territorios defendidos por individuos adultos de Parodon nasus. O estudo foi realizado no corrego Camarinha localizado na Estacao Ecologica Serra das Araras no municipio de Porto Estrela, Mato Grosso, Brasil. A densidade foi constante ao longo de todos os trechos, com media (± desvio padrao) de 1,01 ind./m 2 (± 0,14). Nossos resultados mostram que a distribuicao espacial dos individuos na area variou entre uniforme e aleatoria. Os territorios foram defendidos mais frequentemente contra invasores intra do que interespecificos. O tempo que os detentores de territorio dedicaram a sua defesa nao foi influenciado pelo tamanho dos territorios. Todavia, donos de territorios maiores passaram mais tempo em atividade de forrageamento que donos de territorios menores. Como consequencia, donos de territorios maiores tiveram menos tempo para descansar que donos de territorios menores. Os resultados deste trabalho mostram padroes comportamentais importantes para o entendimento da relacao entre tamanho e custo de manutencao dos territorios de P. nasus e de outras especies de peixes com comportamento territorial.

Temperature affects the hypoxia tolerance of neotropical Cichlid Geophagus brasiliensis

Oxygen and temperature are the most limiting factors in aquatic environments. Several species are exposed to variations of these factors in water because of physical, chemical and biological processes. The objective of this study was to evaluate the metabolic profile and the tolerance to the hypoxia of Geophagus brasiliensis exposed to changes in temperature and oxygen availability. The fish were exposed to 20 and 90% of oxygen saturation combined with different temperatures (20°, 24° and 28° C) for 8 h. Hepatic and muscular glycogen, as well as the activities of lactate dehydrogenase (LDH), malate dehydrogenase (MDH), citrate synthase (CS) and their ratios were evaluated. Both glycogen and MDH activity showed a significant difference in the liver. While CS showed increased activity only in the heart. The increase in LDH activity in the white muscle shows the importance of the anaerobic pathway as energy source in this tissue. The MDH / LDH ratio increased in all tissues, while CS / LDH increased in the liver and decreased in the heart. Based on the results of the present study it may be concluded that this species used the anaerobic metabolism as the main strategy for hypoxia tolerance.