This chapter describes the breeding cycle of kestrels from egg laying to the nestling-rearing phase. It illustrates the different reproductive strategies of males and females, the endogenous mechanisms and environmental conditions that affect the laying date and the clutch size, the adaptive meanings of egg volume and of hatching asynchrony, and the factors that affect the probability of nestlings surviving until fledging.

Production of secondary sexual traits is a key component of reproductive investment in many sexually reproducing species. In this chapter, we have illustrated the secondary sexual traits and behaviours that are implicated in mate choice; the potential meaning of colourations of females and of their eggs as postmating sexual traits; and the signalling role of colourations in young kestrels. We have also described the biochemical bases of body colourations and the physiological costs associated with their production.

The family Falconidae constitutes a group of small to medium-sized diurnal raptors whose monophyly is strongly supported. Kestrels are included in the subfamily Falconinae. There are at least 13 species that belong to the kestrel group, but recent genetic studies suggest that the number of kestrel species might be larger, possibly 16. The paleontological and molecular evidence are congruent in suggesting an evolutionary radiation of kestrels from the Late Miocene (5.6–9.8 million years ago) through the Early Pleistocene. However, the geographic area where kestrels have originated and dispersed from is as yet unclear.

The common kestrel is a generalist predator. However, it also shows significant within-species variation in food habits, such as local specialisations on given prey (e.g. voles in northern or lizards in southern Europe) or even individual food preferences. This chapter illustrates the factors that affect the diet composition of kestrels, their foraging strategies and the processes of food competition, including kleptoparasitism. It also explores the last-generation techniques, such as stable isotope analyses and accelerometer-GPS loggers, that would enable the limits of classic methods used to study the feeding ecology of kestrels to be overcome.

The quantification of physiological and immunological functions provides fundamental information on individual state. It fosters our understanding of the costs of and constraints on life-history strategies. Research in this area on kestrels has mainly focused on immunity, energetics, hormones and antioxidants. This chapter discusses the factors that impact the immune function and describes a number of parasites and pathogens that can be detected in kestrels. It shows how the different phases of reproduction face males and females with different energetic and physiological demands. It discusses the costs associated with sibling competition, and how male and female nestlings may differ in how they optimise the trade-off between growth and self-maintenance. Finally, this chapter describes the moult phase, which represents an understudied feature of kestrel biology.

The common kestrel is evaluated as Least Concern at global level. However, at the European level, the species is considered of conservation concern due to a continuous moderate decline since the 1980s due to agriculture intensification, landscape simplification, pesticide use and loss of nesting sites. Moreover, the conservation status of some subspecies of common kestrel appears problematic. This chapter discusses the conservation status of kestrel species and subspecies, and the main top-down and bottom-up factors that affect the viability and stability of their populations. It also points out the strong limitations of our knowledge about the density-dependent and independent processes that regulate the demography and dynamics of kestrel populations. Important conservation-related topics, such as urbanisation, pesticides, or use of artificial nest boxes, have been discussed in detail in prior chapters.

The number of birds breeding in a given area (breeding density) is affected by several abiotic and biotic factors. Availability of suitable nesting sites plays a major role in determining the size of the local breeding population of birds, particularly in those species, like the common kestrel, that do not build their own nests. Kestrels do actually use old nests of corvids or holes in buildings to breed. By provisioning kestrels with artificial nest boxes, it is possible to increase the number of breeding individuals and, possibly, the population size. However, a number of factors need careful consideration to evaluate a priori the characteristics of nest boxes and locations to install them and to assess a posteriori the effects of the nest box provisioning on the reproductive ecology and population dynamics of kestrels.

Chimpanzees can be caring, affectionate, sensitive animals – toward particular individuals. In the right circumstances. The love and attention a chimpanzee mother showers on her infant is extraordinary, in both its day-to-day manifestation and over the long, five-year span of infancy – the chimpanzee mother–infant bond is arguably even more intense than that of humans (Hrdy, 2011). And it is not just mothers. Males spend hours grooming one another. They look to their friends and allies for comfort and reassurance. When the chips are down and two lifelong friends face a marauding band from another community, they will risk their lives to support one another. Yet, these prosocial bonds are only half the story, if that. In this chapter we will consider how violence shapes social behavior within communities; in the next chapter we will turn toward the war-like aggression that typifies intercommunity relations; in the chapter after that we will tidy up the trilogy with an examination of how profoundly intercommunity violence has affected the relationships within communities. It is this interplay, the effect the threat of intercommunity violence has on minute-to-minute interactions within communities, that makes chimpanzee society so complicated. So complicated, in fact, that it will require 40 steps to knit every aspect of chimpanzee biology together in the final chapter.

In captivity, chimpanzees seem … inadequate: confused; incompetent; to be pitied. Even when happy in captivity, by which I mean not driven to psychosis by solitary confinement or boredom, they seem out of their depth, lost in a human world that is complex beyond their imagining.

The extraordinary feats of memory and reasoning that chimpanzees display – both in the wild and in captivity – are generated by an organ scarcely larger than a grapefruit. But while chimpanzee brains are markedly smaller than those of humans, their brain anatomy is so similar that a discourse comparing the two might be little different from this declaration: The chimpanzee brain is a human brain with one-third of the neurons (Herculano-Houzel & Kaas, 2011). In this chapter we will consider the structure of the brain and its function, drawing mostly on research on humans, and we will speculate about the role size plays in how human and chimpanzee brains work (Duvernoy, 1999; Buzsaki, 2006; Schoenemann, 2006).