Ecophysiology Of Desert Birds

In the Preface to his volume on Ecophysiology of the Camelidae and Desert Ruminants in this series, Trevor Wilson mentions his hesitation at the invitation from John Cloudsley-Thompson to write the book, because he had been out of direct touch with desert biology for some years. My response to John's invitation to write Ecophysiology of Desert Birds was much the same, and for the same reasons. However, with his encouragement and, taking account of the fact that a colleague of mine who is much better suited to do the job had turned it down because of pressure of work, I accepted the challenge and have enjoyed it immensely. It has been my privilege to spend much time in the deserts of North and South America, southern Africa and Australia, some of it with my wife, Cherie, whose editing of the entire text has improved the work immeasurably. Indeed, I believe it would have been proper for her to accept coauthorship, but she graciously declined the offer! I owe her a debt of gratitude which I hope will be repaid in part by her seeing the text finally between covers. The chapters on water regulation (Chap. 5) and thermo regulation (Chap. 6) have benefited from the refereeing of my colleague, Dr. Barry Lovegrove, of the Department of Zoology and Entomology, University of Natal, Pietermaritzburg.

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.

Birds have colonized almost every terrestrial habitat on the planet - from the poles to the tropics, and from deserts to high mountain tops. Ecological and Environmental Physiology of Birds focuses on our current understanding of the unique physiological characteristics of birds that are of particular interest to ornithologists, but also have a wider biological relevance. An introductory chapter covers the basic avian body plan and their still-enigmatic evolutionary history. The focus then shifts to a consideration of the essential components of that most fundamental of avian attributes: the ability to fly. The emphasis here is on feather evolution and development, flight energetics and aerodynamics, migration, and as a counterpoint, the curious secondary evolution of flightlessness that has occurred in several lineages. This sets the stage for subsequent chapters, which present specific physiological topics within a strongly ecological and environmental framework. These include gas exchange, thermal and osmotic balance, 'classical' life history parameters (male and female reproductive costs, parental care and investment in offspring, and fecundity versus longevity tradeoffs), feeding and digestive physiology, adaptations to challenging environments (high altitude, deserts, marine habitats, cold), and neural specializations (notably those important in foraging, long-distance navigation, and song production). Throughout the book classical studies are integrated with the latest research findings. Numerous important and intriguing questions await further work, and the book concludes with a discussion of methods (emphasizing cutting-edge technology), approaches, and future research directions.

My interest in the behaviour and movements of birds of arid and semi-arid ecosystems began when my wife, Sue Milton, and I were Roy Siegfried, Director, at that time, of the Percy approached by Prof. FitzPatrick Institute of African Ornithology, to set up a project to investigate granivory in the South African Karoo. Sue and I spent some time finding a suitable study site, setting up accommodations and an automatic weather station at Tierberg, in the southern Karoo near the village of Prince Albert, and planning projects. Among our first projects was a transect where we noted plant phe nology, measured seed densities on the soil surface, counted birds, observed ant activity, measured soil surface temperatures and col lected whatever climate data we could at 40 sites along a 200-km oval route. Along the way, we became interested in the marked presence and absence of birds at certain sites - abundant birds one day, and very few birds at the same site a month later. Subsequent counts along fixed transects through shrublands confirmed that a number of bird species were highly nomadic over short and long distances, locally and regionally, leading to speculation on how widespread these movements were in the arid ecosystems of the world.

Examining avian physiology in detail, this text specifically addresses the unique physiological characteristics of birds, although experimental techniques and future research directions are also considered.

Since small mammals have a large surface to mass ratio, one would expect them to quickly dehydrate and perish at high environmental temperatures. Nonetheless, a large number of small mammal species inhabit deserts. This fascinating phenomenon is investigated by Prof. A. Allan Degen in his book. The majority of small desert mammals are rodents, but shrews of several grams and small foxes of 1 kg are also present. Their survival is due mainly to behavioural adaptations and habitat selection, however, physiological adaptations also contribute to the success. Interestingly, many small mammals that live in different deserts of the world show similarities in their adaptive traits although they have different taxonomic affinities.

Following a description of the physical and biological characterization of the four North American deserts together with the primary adaptations of plants to environmental stress, the authors go on to present case studies of key species. They provide an up-to-date and comprehensive review of the major patterns of adaptation in desert plants, with one chapter devoted to several important exotic plants that have invaded these deserts. The whole is rounded off with a synthesis of the resource requirements of desert plants and how they may respond to global climate change.

A description of the structural and functional adaptations of the key organs such as skin, kidneys, bladder, lungs and ovaries, with special emphasis placed on physiological adaptations: water, electrolyte, nitrogen, and thermal balance and their endocrine control. One whole chapter devoted to ecological aspects covers such exciting topics as development and metamorphosis, larval competition for food resources, and reproductive strategies.