Understanding the migratory orientation program of birds: extending laboratory studies to study free flying migrants in a natural setting

For many years, orientation in migratory birds has primarily been studied in the laboratory. Although a laboratory-based setting enables greater control over environmental cues, the laboratory-based findings must be confirmed in the wild in free-flying birds to be able to fully understand how birds orient during migration. Despite the difficulties associated with following free-flying birds over long distances, a number of possibilities currently exist for tracking the long distance, sometimes even globe-spanning, journeys undertaken by migrating birds. Birds fitted with radio transmitters can either be located from the ground or from aircraft (conventional tracking), or from space. Alternatively, positional information obtained by onboard equipment (e.g., GPS units) can be transmitted to receivers in space. Use of these tracking methods has provided a wealth of information on migratory behaviors that are otherwise very difficult to study. Here, we focus on the progress in understanding certain components of the migration-orientation system. Comparably exciting results can be expected in the future from tracking free-flying migrants in the wild. Use of orientation cues has been studied in migrating raptors (satellite telemetry) and thrushes (conventional telemetry), highlighting that findings in the natural setting may not always be as expected on the basis of cage-experiments. Furthermore, field tracking methods combined with experimental approaches have finally allowed for an extension of the paradigmatic displacement experiments performed by Perdeck in 1958 on the short-distance, social migrant, the starling, to long-distance migrating storks and long-distance, non-socially migrating passerines. Results from these studies provide fundamental insights into the nature of the migratory orientation system that enables experienced birds to navigate and guide inexperienced, young birds to their species-specific winter grounds.

True navigation in birds: from quantum physics to global migration

Birds are capable of true navigation, the ability to return to a known goal from a place they have never visited before. This is demonstrated most spectacularly during the vast migratory journeys made by these animals year after year, often between continents and occasionally global in nature. However, it remains one of the great unanswered questions in science, despite more than 50 years of research in this field. Nevertheless, the study of true navigation in birds has made significant advances in the previous 20 years, in part thanks to the integration of many disciplines outside its root in behavioural biology, to address questions of neurobiology, molecular aspects, and the physics of sensory systems and environmental cues involved in bird navigation, often involving quantum physics. However, true navigation remains a controversial field, with many conflicting and confusing results making interpretation difficult, particularly for those outside or new to the field. Unlike many general texts on migration, which avoid discussion of these issues, this review will present these conflicting findings and assess the state of the field of true navigation during bird migration.

Observations on some birds procured near Charleston, South Carolina

This document contains notes on eight species of birds observed by Arthur T. Wayne in Charleston, South Carolina including the Horned Grebe, the Yellow-crowned Night Heron, Bachman’s Warbler, the Rocky Mountain Orange-crowned Warbler, the Cape May Warbler, the Black-poll Warbler, the Red-breasted Nuthatch, and the Blue-gray Gnatcatcher.

Notes on seven birds taken near Charleston, South Carolina

This document contains notes on seven species of birds observed by Arthur T. Wayne in Charleston, South Carolina including the Yellow-bellied Flycatcher, the Purple Martin, the Black-throated Blue Warbler, Cairn’s Warbler, Grinnell’s Water-Thrush, the Kentucky Warbler, and the Mockingbird.

Mitochondrial uncoupling as a regulator of life-history trajectories in birds: an experimental study in the zebra finch.

Mitochondria have a fundamental role in the transduction of energy from food into ATP. The coupling between food oxidation and ATP production is never perfect, but may nevertheless be of evolutionary significance. The 'uncoupling to survive' hypothesis suggests that 'mild' mitochondrial uncoupling evolved as a protective mechanism against the excessive production of damaging reactive oxygen species (ROS). Because resource allocation and ROS production are thought to shape animal life histories, alternative life-history trajectories might be driven by individual variation in the degree of mitochondrial uncoupling. We tested this hypothesis in a small bird species, the zebra finch (Taeniopygia guttata), by treating adults with the artificial mitochondrial uncoupler 2,4-dinitrophenol (DNP) over a 32-month period. In agreement with our expectations, the uncoupling treatment increased metabolic rate. However, we found no evidence that treated birds enjoyed lower oxidative stress levels or greater survival rates, in contrast to previous results in other taxa. In vitro experiments revealed lower sensitivity of ROS production to DNP in mitochondria isolated from skeletal muscles of zebra finch than mouse. In addition, we found significant reductions in the number of eggs laid and in the inflammatory immune response in treated birds. Altogether, our data suggest that the 'uncoupling to survive' hypothesis may not be applicable for zebra finches, presumably because of lower effects of mitochondrial uncoupling on mitochondrial ROS production in birds than in mammals. Nevertheless, mitochondrial uncoupling appeared to be a potential life-history regulator of traits such as fecundity and immunity at adulthood, even with food supplied ad libitum.

Birds.

Tiene como objeto explorar los pájaros y ofrecer respuestas a muchos de los qué, por qué y cómo que los niños pequeños preguntan sobre el mundo que les rodea. Para ayudar a los niños a entenderpor qué los pájaros tienen plumas,cómo las aves migratorias encuentran su camino. Cada dos páginas hay tres secciones organizadas por temas:un Ahora sé, es una revisión de los principales aspectos que refuerza lo aprendido. Eso es asombroso, ofrece características destacadas de la costa. Mira y encuentra sirve para alentar a los niños a identificar y asociar nombres con imágenes.

Can salvage logging affect seed dispersal by birds into burned forests?

The recovery of vegetation in Mediterranean ecosystems after wildfire is mostly a result of direct regeneration, since the same species existing before the fire regenerate on-site by seeding or resprouting. However, the possibility of plant colonization by dispersal of seeds from unburned areas remains poorly studied. We addressed the role of the frugivorous, bird-dependent seed dispersal (seed rain) of fleshy-fruited plants in a burned and managed forest in the second winter after a fire, before on-site fruit production had begun. We also assessed the effect on seed rain of different microhabitats resulting from salvage logging (erosion barriers, standing snags, open areas), as well as the microhabitats of unlogged patches and an unburned control forest, taking account of the importance of perches as seed rain sites. We found considerable seed rain by birds in the burned area. Seeds, mostly from Olive trees Olea europaea and Evergreen pistaches Pistacia lentiscus, belonged to plants fruiting only in surrounding unburned areas. Seed rain was heterogeneous, and depended on microhabitat, with the highest seed density in the unburned control forest but closely followed by the wood piles of erosion barriers. In contrast, very low densities were found under perches of standing snags. Furthermore, frugivorous bird richness seemed to be higher in the erosion barriers than elsewhere. Our results highlight the importance of this specific post-fire management in bird-dependent seed rain and also may suggest a consequent heterogeneous distribution of fleshy-fruited plants in burned and managed areas. However, there needs to be more study of the establishment success of dispersed seeds before an accurate assessment can be made of the role of bird-mediated seed dispersal in post-fire regeneration

Blood transfusion in birds

Birds, both companion and wild, have become frequent patients in veterinary clinics and hospitals as well in wildlife rehabilitation centers in the last two decades. In emergency situations, it is imperative to give the best critical care to these patients, which frequently implies reversing shock and re-establishing homeostasis. In order to do so, a blood transfusion can be life-saving. It is important to the clinician to properly evaluate these critical patients and decide when to administer blood or blood products.