P. Berthold and E. Gwinnd Bird migration is an intriguing aspect of the living world - so much so that it has been investigated for as long, and as thoroughly, as almost any other natural phenomenon. Aristotle, who can count as the founder of scientific ornithology, paid very close attention to the migrations of the birds he ob served, but it was not until the reign of Friedrich II, in the first half of the 13th century, that reliable data began to be obtained. From then on, the data base grew rapidly. Systematic studies of bird migration were introduced when the Vogelwarte Rossitten was founded, as the first ornithological biological observation station in the world (see first chapter "In Memory of Vogelwarte Rossitten"). This area later received enormous impetus when ex perimental research on the subject was begun: the large-scale bird-ringing experiment initiated in Rossitten in 1903 by Johannes Thienemann (who was inspired by the pioneering studies of C. C. M. Mortensen), the experiments on photoperiodicity carried out by William Rowan in the 1920s in Canada and retention and release experiments performed by Thienemann in the 1930s in Rossitten, the first experimental study on the orientation of migratory birds. After the Second World War, migration research, while continuing in the previous areas, also expanded into new directions such as radar ornithology, ecophysiology and hormonal control mechanisms, studies of evolution, ge netics, telemetry and others.

Birds have and continue to fascinate scientists and the general public. While the avian respiratory system has unremittingly been investigated for nearly five centuries, important aspects on its biology remain cryptic and controversial. In this book, resolving some of the contentious issues, developmental-, structural- and functional aspects of the avian lung-air sac system are particularized: it endeavors to answer following fundamental questions on the biology of birds: how, when and why did birds become what they are? Flight is a unique form of locomotion. It considerably shaped the form and the essence of birds as animals. An exceptionally efficient respiratory system capacitated birds to procure the exceptionally large quantities of oxygen needed for powered (active) flight. Among the extant air-breathing vertebrates, comprising ~11,000 species, birds are the most species-rich-, numerically abundant- and extensively distributed animal taxon. After realizing volancy, they easily overcame geographical obstacles and extensively dispersed into various ecological niches where they underwent remarkable adaptive radiation. While the external morphology of birds is inconceivably uniform for such a considerably speciose taxon, contingent on among other attributes, lifestyle, habitat and phylogenetic level of development have foremost determined the novelties that are displayed by diverse species of birds. Here, critical synthesizes of the most recent findings with the historical ones, evolution and behavior and development, structure and function of the exceptionally elaborate respiratory system of birds are detailed. The prominence of modern birds as a taxon in the Animal Kingdom is underscored. The book should appeal to researchers who are interested in evolutionary processes and how adaptive specializations correlate with biological physiognomies and exigencies, comparative biologists who focus on how various animals have solved respiratory pressures, people who study respiration in birds and other animals and ornithologists who love and enjoy birds for what they are – profoundly interesting animals.

E. GWINNER! The phenomenon of bird migration with its large scale dimensions has attracted the attention of naturalists for centuries. Worldwide billions of birds leave their breeding grounds every autumn to migrate to areas with seasonally more favor able conditions. Many of these migrants travel only over a few hundred kilo meters but others cover distances equivalent to the circumference of the earth. Among these long-distance migrants are several billion birds that invade Africa every autumn from their West and Central Palaearctic breeding areas. In the Americas and in Asia the scope of bird migration is of a similar magnitude. Just as impressive as the numbers of birds are their achievements. They have to cope with the enormous energetic costs of long-distance flying. particularly while crossing oceans and deserts that do not allow replenishment of depleted fat reserves. They have to appropriately time the onset and end of migrations. both on a daily and annual basis. And finally. they have to orient their migratory movements in space to reach their species- or population-specific wintering and breeding grounds, irrespective of the variable climatic conditions along their migratory routes.

Temperature plays a critical role in animal survival and climate warming is one of the greatest threats to global biodiversity in the future. It is already affecting species and communities with severe impacts and it is predicted that climate warming will cause species extinctions and distributional shifts in the coming decades. The impact of climate warming is expected to be particularly severe on ectothermic animals, including fishes, amphibians, and reptiles. Thus, assessing species’ responses to ongoing climate warming and determining what conservation actions should be taken are among the most significant and controversial challenges for ecologists. Identifying the most vulnerable species to extinction as a result of climate warming is an appropriate first step in mitigating the impacts of a changing world. An organism’s vulnerability to climate warming depends on its sensitivity to environmental changes, its exposure to the change, and its ability to recover from and potential to adapt to change. The interaction of these factors makes predicting the effects of climate warming on species a complex and major challenge for ecologists. Developing a deeper knowledge of ectotherms’ vulnerability to climate warming is crucial to enhance our understanding of extinction processes and significantly contribute to conservation efforts by guiding the implementation of better policies and management strategies to prevent the extinction of remaining populations. Investigations of climate warming vulnerability are likely to benefit from measurements of environmental conditions taken at the scale at which organisms experience them. Therefore, the main objective of this interdisciplinary Research Topic is to bring together research on how ectotherms respond to climate warming at various levels. We will particularly focus on the life-history, energy strategy, physiological response, etc. We encourage inter-and multidisciplinary research approaches linking molecular biology, thermal physiology (and ecology), behavioral ecology, functional ecology, evolutionary genetics, and bioenergetics.

Cave organisms are the ‘monsters’ of the underground world and studying them invariably raises interesting questions about the ways evolution has equipped them to survive in permanent darkness and low-energy environments. Undertaking ecological studies in caves and other subterranean habitats is not only challenging because they are difficult to access, but also because the domain is so different from what we know from the surface, with no plants at the base of food chains and with a nearly constant microclimate year-round. The research presented here answers key questions such as how a constant environment can produce the enormous biodiversity seen below ground, what adaptations and peculiarities allow subterranean organisms to thrive, and how they are affected by the constraints of their environment. This book is divided into six main parts, which address: the habitats of cave animals; their complex diversity; the environmental factors that support that diversity; individual case studies of cave ecosystems; and of the conservation challenges they face; all of which culminate in proposals for future research directions. Given its breadth of coverage, it offers an essential reference guide for graduate students and established researchers alike.