RESUMEN
Identifying the processes that determine avian migratory strategies in different environmental contexts is imperative to understanding the constraints to survival and reproduction faced by migratory birds across the planet.We compared the spring migration strategies of Fork-tailed Flycatchers (Tyrannus s. savana) that breed at south-temperate latitudes (i.e., austral migrants) vs. tropical latitudes (i.e., intratropical migrants) in South America. We hypothesized that austral migrant flycatchers are more time-selected than intratropical migrants during spring migration. As such, we predicted that austral migrants, which migrate further than intratropical migrants, will migrate at a faster rate and that the rate of migration for austral migrants will be positively correlated with the onset of spring migration.We attached light-level geolocators to Fork-tailed Flycatchers at two tropical breeding sites in Brazil and at two south-temperate breeding sites in Argentina and tracked their movements until the following breeding season.Of 286 geolocators that were deployed, 37 were recovered ~1 year later, of which 28 provided useable data. Rate of spring migration did not differ significantly between the two groups, and only at one site was there a significantly positive relationship between date of initiation of spring migration and arrival date.This represents the first comparison of individual migratory strategies among conspecific passerines breeding at tropical vs. temperate latitudes and suggests that austral migrant Fork-tailed Flycatchers in South America are not more time-selected on spring migration than intratropical migrant conspecifics. Low sample sizes could have diminished our power to detect differences (e.g., between sexes), such that further research into the mechanisms underpinning migratory strategies in this poorly understood system is necessary.
RESUMEN
This work constitutes a record of vascular plant species used for therapeutic purposes on Santiago Island, located in the Rio de La Plata, southeast of the Party of Ensenada, Buenos Aires, Argentina. The island has an area of 8 km2 and consists of alluvial land, with natural and rich floristic environments. Eighty three households were sampled, plant specimens were collected in-situ, were identified using specific literature and binocular magnifying glass, and a digital photographic record was made. We identified 40 species of vascular plants, used by the islanders in folk medicine, mostly exotic and herbaceous. Also, 32 therapeutic uses and 11 affections were reported. The digestive and skin disorders were the most representative.
Este trabajo constituye un registro de especies de plantas vasculares utilizadas con fines terapéuticos en la Isla Santiago, ubicada en el Río de La Plata, al SE del Partido de Ensenada, provincia de Buenos Aires, Argentina. La isla, tiene una superficie de 8 km2 y está formada por tierras de origen aluvional, con ambientes naturales de gran riqueza florística. Se muestrearon 83 unidades domésticas, se recolectaron ejemplares vegetales in-situ, se identificaron utilizando bibliografía específica y lupa binocular y se hizo un registro fotográfico digital. Se identificaron 40 especies de plantas vasculares, utilizadas por los isleños en medicina popular, la mayoría exóticas y herbáceas. Asimismo, se reportaron 32 usos terapéuticos y 11 afecciones; los trastornos digestivos y de la piel fueron los más representativos.