André de Camargo Guaraldo

Contrasting annual cycles of an intratropical migrant and a tropical resident bird

AbstractThroughout their annual cycle, migrants often adopt different foraging and microhabitat usage strategies. Previous studies treat migrants as niche-trackers/niche-followers, i.e., they track similar niches along their annual cycle, almost exclusively based on food resource availability, which is inferred based on the climate at either the wintering or breeding grounds. An alternative approach is the use of such techniques as stable isotope analyses that allow researchers to more directly infer a migrant’s niche across seasons. While the use of carbon isotopes enables an assessment of microhabitat traits, that of nitrogen isotopes provides information on a bird’s trophic level. In the study reported here, we performed comparative analyses of stable carbon and nitrogen isotope ratios in tissues of the resident Plain-crested Elaenia and the intratropical migrant Lesser Elaenia to evaluate their year-round ecological niches. Our data suggest that both residents and migrants were consistent in their use of similar microhabitats throughout the year, which indicates a niche-tracking behavior on the part of migratory individuals. Migrants often fed at higher trophic levels than residents, but both species exhibited similar trophic level shifts through the year, feeding on higher trophic levels during breeding and on the lowest ones while wintering. The observed patterns could be due to several factors, including differential energetic demand needed for the migratory journey, species-specific nutritional needs during each stage of the year, and/or the use of multiple wintering grounds by migrants.ZusammenfassungAbweichende Jahreszyklen eines innertropischen Zugvogels und eines tropischen Standvogels Im Verlauf ihres Jahreszyklus verfolgen Zugvögel häufig unterschiedliche Strategien bei der Nahrungssuche und in der Wahl des Mikrohabitats. In früheren Untersuchungen wurden Zugvögel als Nischenfolger behandelt, d. h. sie folgen im Jahresverlauf ähnlichen ökologischen Nischen, fast ausschließlich aufgrund der Verfügbarkeit von Nahrungsressourcen, auf welche anhand des Klimas in Überwinterungs- beziehungsweise Brutgebieten geschlossen wurde. Alternativ erlauben es Techniken wie die Analyse stabiler Isotope, auf eine direktere Weise auf die von einem Zugvogel im Verlauf der Jahreszeiten besetzten Nischen zu schließen. Während Kohlenstoffisotope eine Einschätzung der Mikrohabitateigenschaften ermöglichen, liefern Stickstoffisotope Informationen über die Trophieebene eines Vogels. In dieser Studie führten wir vergleichende Analysen der Verhältnisse stabiler Kohlenstoff- und Stickstoffisotope an Gewebeproben des Braunscheitel-Olivtyranns Elaenia cristata, eines Standvogels, sowie des innertropisch ziehenden Grauwangen-Olivtyranns Elaeniachiriquensis durch, um deren ökologische Nischen im Jahresverlauf auszuwerten. Unsere Daten legen nahe, dass sowohl die ortsansässigen Standvögel als auch die Durchzügler gleichbleibend das ganze Jahr über ähnliche Mikrohabitate nutzten, was auf ein Nischenfolger-Verhalten bei den ziehenden Individuen hindeutet. Die Zugvögel befanden sich bei der Nahrungssuche oft auf höheren Trophieebenen als die Standvögel, aber beide Arten zeigten ähnliche Verschiebungen der Trophieebene im Jahreslauf, indem sie zur Brutzeit auf höheren Trophieebenen nach Nahrung suchten und beim Überwintern die niedrigsten einnahmen Den beobachteten Mustern könnten verschiedene Faktoren zugrunde liegen, darunter ein abweichender Energiebedarf auf dem Zugweg, artspezifische Nährstoffansprüche zu jeder Phase im Jahreslauf sowie die Nutzung multipler Überwinterungsgebiete durch Zugvögel.

Fenologia e produção de frutos de Caryocar brasiliense Cambess. E Enterolobium gummiferum (Mart.) J.F.Macbr. em diferentes regimes de queima

The knowledge of plant reproductive and vegetative periods is extremely important for seed harvesting and seedling production. Interactions between the Cerrado (Brazilian Savanna) biota and fire are of extreme interest because these factors are intimately related and could be determinant in plant populations maintenance. For 12 months, we studied the phenology of two Cerrado native species (Enterolobium gummiferum (Mart.) J.F.Macbr. and Caryocar brasiliense Cambess.) under two fire regimes: the first was burned every two years on August (PBM) in a control site without fire for 14 years (PC). Uniformity tests were made to verify seasonality of each phenological phase. The model selection with Akaike information criterion was made using climatic variables of the study region to identify which variables better describe the phenological phases. Fruit production was estimated for both treatments. Almost every phenophase showed production peaks, except for leaf sprout of C. brasiliense in PC and leaf fall of C. brasiliense in the two treatments, and E. gummiferum in PC. In general, the phenological behaviour of both species did not differ from other studies. However, fire retarded the leaf renewal and inhibited the reproductive phases of C. brasiliense, similar to previous results for other Cerrado native species in regions with burn incidence.

Nestling Behavior and Parental Care of the Common Potoo (Nyctibius griseus) in Southeastern Brazil

Abstract We recorded and quantified the nocturnal activity and parental care of a brooding Common Potoo (Nyctibius griseus) using an infrared camera in southeastern Brazil. Parents alternated care of the nestling and decreased their presence as the nestling grew. Nestling feeding on passing insects while sitting on the nest, movements on the nest, wing exercising, preening, and defecating were recorded primarily while it was alone. The frequency of begging calls per hour was higher when the nestling was accompanied by one of the parents. Nocturnal recordings of this species on the nest revealed behaviors that were not cited in past studies, including: feedings bouts on passing flies performed by the nestling and adults, nestling defecation, and nestling plumage maintenance. The well-known plus newly quantified behaviors of the Common Potoo reinforce their value to survival during the long nestling period.

Breeding of the Spot-billed Toucanet (Selenidera maculirostris) in the wild.

Abstract The Spot-billed Toucanet (Selenidera maculirostris) is an endemic member of the Ramphastidae occurring in the Atlantic Forest in Brazil. There is anecdotal literature about this species breeding in the wild, but no data are available about parental behavior and nest morphometry. We describe observations of parental behavior of the Spot-billed Toucanet including measurements of one nest in Ilha do Cardoso State Park, São Paulo, Brazil. The nest was inside a hollow of a Lauraceae tree with the entrance hidden by leaves of Aechmea sp. (Bromeliaceae). The Spot-billed Toucanet, based on our observations and review of the literature, nests in tree cavities between 2 and 7 m above ground and both parents provision the nestlings.