The Story of Birds

A lovely and well-written book that tells the story of birds, from their start in the Jurassic, the appearance of many archaic and modern birds after the asteroid wiped out many species (including the non-avian dinosaurs), to the many kinds of birds now found today, both living and recently extinct. One thing the author is at pains to make clear: birds are dinosaurs, just as humans are mammals, so saying the dinosaurs are extinct is incorrect.

What follows is a chapter by chapter summary of the book.

The first chapter states the fact that birds are dinosaurs. This was known since the time of Charles Darwin, when similar anatomical features were found in the fossils of dinosaurs and the bones of birds. As the number of dinosaur fossils increased, opposition to the idea grew as no direct ancestor of birds could be pointed out among the dinosaurs. The later discovery of Deinonychus and other similar dinosaurs would revive the link, this time by pointing out specific similarities between Deinonychus and birds. Then developmental biology discovered that the embryos of developing birds mimic anatomical features of the dinosaurs. Some dinosaurs also became smaller, and started to develop postures that resemble those of birds. The evidence that birds were descended from dinosaurs has now become stronger.

Chapter two looks at the evolution of feathers. Feathers are a defining feature of birds. They are part of the skin and made out of the same protein used by reptiles to make claws and scales. Feathers can create bristles (the most basic form), down or flight feathers. The discovery of dinosaur fossils with bristles was dramatic and hailed as more evidence for a link between birds and dinosaurs. Soon, more dinosaur fossils with feathers were discovered. While not as elaborate as bird feathers, the feathers were hypothesised to help dinosaurs regulate their body temperate and then reused for elaborate sexual displays. As some dinosaurs got smaller, and their feathers became more developed, flight feather eventually developed, leading to some dinosaurs that are able to glide and move about in the air.

Chapter three looks at the evolution of flight and the demands flight makes on the bodies of birds. The well known Archaeopteryx is considered by the author as a bird as it many of the features of a bird, like flight feathers, despite lacking a breastbone and muscles for strong, powered flight. For details on that, the author looks at the extinct group of birds known as the enantiornithnes ('opposite birds'). These birds lost most of their tail bones and teeth and developed beaks. This changed the way bird's digestive systems works, developing a crop and gizzard to digest their food in a compact way. Birds rearranged and grew large muscles to power their flight, anchored to a strong and large breastbone. Their also crouched to manage their balance, locking their thigh bones and using only their lower legs for locomotion.

Chapter four looks at the group of birds that would eventually give rise to modern-day birds. By the end of the Cretaceous, different groups of birds have developed. The one that produced modern birds (the 'crown group' of birds) have features that separated them from other bird groups, like the enantiornithnes. These birds grew smaller, developed flexible, specialised beaks to handle different kinds of food (like seeds), and grew fast, becoming adults in less than a year. They also developed the syrinx (the birds' voice box).

Chapter five looks at the catastrophe that would signal the end of the reign of the dinosaurs. The asteroid impact would wipe out all creatures larger than a dog, leaving mainly those that could burrow, fly or swim to safety (reptiles, mammals, modern-day birds). It is hypothesised by the author that the features that characterised the surviving birds (small size, grown dwelling, ability to handle small foods like seeds) are the features that enabled this group of birds to survive the disaster. Another feature of such birds are large brains (relative to body size) which may have helped them to cope with the new environment they were suddenly thrown into.

Chapter six looks at the evolution of birds after the asteroid strike. Genetic studies, and fossil evidence, shows that all the major groups of modern birds evolved quickly. Wings developed into many shapes and sizes suitable to the way birds fly, from those that soar with little effort, to those with high speeds and high manoeuvrability. Beaks evolved based on the birds' diets. Since birds fly, they can be found all over the world. Fossils of tropical bird species have been found in Europe and elsewhere, an indication of the warmer climates in the past. The changing climate and geography of Earth would influence the further evolution of birds.

Chapter seven looks at the birds that have given up flight to live on land or in the oceans. Flying is hard, and when birds end up in environments where flight is not needed, like islands with few bird predators, birds can give up flying and live on the ground, and possibly growing bigger in the process. The author looks at flightless birds like the cassowary, ostrich, rhea, moa and kiwi. DNA studies show that these birds have a common flying ancestor, meaning they all gave up flying independently. Penguins are one bird that gave up flight for swimming. Giant penguins dominated the ancient oceans, until the whales and seals came along. Today, only the tropical heat prevents penguins from venturing into northern oceans.

Chapter eight looks at several extraordinary birds that have gone extinct. The author starts with the terror birds of South America, huge birds with large beaks and talons. In the north, giant birds known as gastornithids can be found. Chemical clues in the fossils show that unlike the terror birds, gastornithids ate plants. Giant birds were also found in Australia (known as 'demon ducks'). And in the air, huge birds with wingspans twice as large as today's birds were soaring. The author closes with one of the best known birds to have gone extinct: the Dodo.

Chapter nine looks at research being done by the author and other scientists on modern birds. Despite their small size, birds turn out to be very intelligent, with brains densely packed with neurons. Some birds can recognise themselves in mirrors, and the intelligence of corvids (crows, ravens) and parrots is now accepted. Songbirds are not born with songs in their heads, but learn them via social interaction with their parents and other birds. Domestication has also given rise to birds like pigeons and chickens, which are now the most numerous birds in the world.

The epilogue looks at the future of birds. Many people love and admire birds, but birds are in trouble. Extinction rates of birds are high, with many documented like the extinction of the dodo. Large bird populations do not guarantee safety from extinction, as the extinction of the passenger pigeon (which once numbered in the billions) shows. But there have been successes in saving birds, as the recovery of the Californian condor and bald eagle shows. Birds have survived the extinction of the non-avian dinosaurs and, with some help from us, may help survive modern day climate change and habitat destruction.

The book ends with copious endnotes that will guide readers to look up the reference materials used by the author in writing this book.