I am an evolutionary biologist and have spent most of my career to date investigating how the reproductive behaviour of birds drives the process of speciation and the amazing diversity of birds that we hear and see around us.
Reproductive behaviour can be broken down into many components, such as: the expression of ornaments like colourful plumage; the process of choosing a social partner to breed with; how many offspring to have; how many sons or daughters to have; how much investment you make in current or future offspring. All of these decisions affect the quality of the resulting offspring. It is the variation in quality amongst individuals in a population that the process of natural selection acts upon. The best quality individuals are likely to be more attractive, live longer and produce more offspring than individuals or lower quality. Over generations, the population will change as a result of this non-random selection and eventually a new species is born.
Birds have provided a disproportionate level of insight into evolutionary biology over the past hundred years because they are well surveyed, well understood and highly amenable to morphological and behavioural research. Developing a better knowledge of avian reproductive behaviour increases our capacity to conserve biodiversity and understand ourselves, because most birds share the same socially monogamous mating system as humans – a system that is actually very rare among other mammals.