Populations, communities, and conservation

In this final chapter populations, population change, and population regulation are discussed, particularly in the context of threats to species and the conservation strategies employed to protect them. Population size, structure, and distribution in relation to ecology and habitat availability are analysed. The movements and establishment of species through natural range expansion and through introduction are considered in the context of climate change, conservation, and threat. The impact and management of emerging avian diseases is discussed. Extinction, the threat of extinction, and conservation efforts are considered and throughout the chapter the roles of professional and citizen scientist ornithologists are emphasized.

Foraging and avoiding predators

The chapter considers the generalist and specialist diets of birds, and the behaviours and adaptations used by birds to find food. Special attention is given to the threat to birds from plastics pollution and the impact of plastic ingestion. Cooperative foraging and cooperative hunting are discussed as are the behaviours adopted by birds that do not cooperate or share. Feeding behaviour is considered in light of the theory of optimal foraging, particularly in relation to prey choice and to the balancing of risk. The impact of urban living upon the diets and foraging behaviours of birds is discussed. A broad range of predator avoidance behaviours are described and evaluated.

Eggs, nests, and chicks

This chapter considers the egg from its conception, through laying and incubation, to hatching; and chicks. It begins with the genetic determination of sex in birds, the resultant secondary sexual characteristics, and associated reproductive behaviours. The chapter then considers the structure and function of the egg. The evolution of clutch size and the trade-offs related to food availability and predator risk that birds make when optimizing clutch size are discussed. Egg shell colouration, camouflage, and mimicry are explored as are the impacts of urban living and of anthropogenic pollution upon egg shell thickness and strength. Nest building and the function of nests are described and incubation behaviours are discussed. Embryonic development is considered as are hatching and post-hatching behaviours.

Feathers and flight

This chapter covers two themes: feathers and flight. It takes a close look at the many aspects of feathers—their evolution, structure, growth, maintenance, and their replacement through moult. The broad range of functions of feathers in display (including how different pigmentations arise), for insulation, and in flight are considered. Moult strategies are compared and discussed. The second part of the chapter describes the anatomical adaptations of birds to flight, and the process of flight itself. The basic physics, physiology and metabolism, and energetics of flight are covered in some detail. A review of studies on the neurological control of collision avoidance by flying birds and the implications in relation to wind-farm collision risk is given. The chapter ends with a discussion on the evolution of flight and subsequent flightlessness of some bird species.

Movement: migration and navigation

Using migration and navigation as a focus, this chapter looks at the movements of birds. The genetic, hormonal, and physiological control of migration is analysed as are the evolution of migratory strategies and routes. Particular emphasis is given to fuelling migration and the significance of stop-over behaviours during migratory movements. The conservation implications of migration and of movement in general are considered, and the impact upon migratory fuelling of neonicotinoids pesticides are discussed. Sections examining innate and learned route finding and the migratory cues (sun, stars, magnetic field, etc) used by birds to determine their location, and the direction in which they need to travel to arrive at a goal, are given. The role of memory in place finding and food storage is considered, as is the neurology of spatial memory. Techniques used by ornithologists to study bird movement are explained throughout the chapter.

Reproduction

In this chapter the diverse mating systems exhibited by birds are described and explained. The chapter begins with a discussion of anisogamy and resulting behavioural differences exhibited by male and female birds. Sperm competition, sperm storage, and delayed fertilization are discussed and their consequences in terms of reproductive behaviours and systems are explained. Courtship systems and behaviours are discussed. Social monogamy, polygamy, and lekking behaviour are examined and examples of field research are given to support offered hypotheses. Bird song is considered in some detail through discussion of the function of song and of the genetic, neurological, and physiological control of singing. Particular attention is given to the impact of noise pollution on singing behaviour. The chapter concludes with a discussion of chick rearing including brood size management.

Evolution of birds

This chapter explores the evolutionary history of birds. It considers the dinosaur origins of birds and the evolution of the modern bird lineages. The development of the modern bird from its prehistoric, reptilian ancestors is analysed by discussion of important fossil specimens, particularly that of Archaeopteryx, and the development of both morphological and biomolecular phylogenies. Evolution by natural selection is explained, as are processes of evolutionary adaptation and speciation. The conservation implications of hybridization are considered and the classification and nomenclature of birds is introduced. Throughout the chapter examples of current research are presented alongside established classic studies to engage the reader and provide a route into the relevant scientific literature.