of spooky graveyard thrillers. However, many owls do not hoot at all. Other sounds vary from the hissing screams of barn owls to the insect-like chirruping of scops owls, the metronomic whistles of pygmy owls and the dog-like yapping of the aptly named Barking Owl. Calls are unique to each species and, for the scientist and birdwatcher, they provide diagnostic clues to an owl’s identity.
Owls are unusual among birds in that most do not visibly open their bills when calling but rather inflate their throats, like a frog. They are most vocal at the start of the breeding season, as males reclaim their territories and attract females. Most species are monogamous, and many form lifelong pairs, retaining the same territory and nest sites for numerous years. In addition to calls, pairs consolidate their bonds with mutual preening, gifts of food from male to female, and choreographed courtship rituals, including wing-clapping display flights.
Males show their mates around potential nest sites, but females generally make the choice. Most nest in tree holes, especially those excavated by woodpeckers, but some use crevices among rocks and tree roots. Many will also reappropriate the old stick nest of another bird, such as a crow or raptor, and a few even nest in a crude hollow on the ground, trampled into the long grass. None constructs a nest, and few provide any kind of lining. Owls’ eggs are generally white and quite spherical in shape, with the clutch size ranging from one or two in many species to an amazing dozen or more, during peak years, for those whose breeding is tied to the abundance of prey such as voles. The female generally incubates the clutch, while the male hunts to provide for her. Once the hatchlings have grown strong enough, both parents hunt together in order to provision their voracious brood. Although owls may be poor nest builders, they are excellent nest defenders, and species such as the Tawny Owl and Ural Owl are notorious for the attacks they launch on intruders. Other tactics are deployed, including puffing up the feathers to exaggerate their size, and feigning injury to distract an approaching predator away from the vulnerable chicks.
The youngsters grow quickly and generally leave the nest before they are fully fledged, hanging around for a while in a downy mesoptile stage before they perfect their flying and start to hunt for themselves. The young of some larger owls may remain with their parents for several months, sometimes long enough to prevent the parents from breeding the following year. In many species, especially those found in colder northern regions, breeding success is dictated by weather and food supply, and in poor years they may not attempt to breed. Once an owl gets through its tricky early years, many species go on to live long lives. Longevity records among captive owls have topped fifty years for both the Eurasian Eagle Owl and the Great Horned Owl.
Owls and people
Owls have played a significant part in human culture since before recorded history, their all-seeing eyes inspiring both fear and reverence, and prompting their symbolic depiction as, variously, harbingers of doom and emblems of wisdom and prosperity. They appear in French cave paintings dating back 15,000 to 20,000 years and in the hieroglyphics of the ancient Egyptians. In the United Kingdom, the spectral appearance and eerie call of the Barn Owl has led to numerous ghost stories, while in Jamaica the presence of a Jamaican Owl outside a house has occupants reciting an incantation to avert disaster. In Japan, conversely, Blakiston’s Fish Owl is revered by the Ainu people as “The God that Protects the Village.”
Whatever we think of owls, humans have given them plenty to contend with. In some parts of the world, owls have suffered direct persecution, either killed to ward off evil spirits or hunted for the pot. More serious, however, is the damage done to their environments. Deforestation, commercial agriculture, and river pollution have robbed owls of the habitats they need for breeding and hunting, while the use of rodenticides and other toxins have not only depleted the owls’ prey but often caused secondary poisoning to the birds themselves. Modern hazards also include man-made obstacles such as power lines and road traffic. Today, the International Union for the Conservation of Nature lists six owl species as Critically Endangered, twenty-six as Endangered, and another forty-three as Vulnerable or Near Threatened. As indicator species of a healthy environment, it is therefore the disappearance of owls, rather than their presence, that we should fear as a harbinger of doom.
Conservationists are doing their bit. BirdLife International and its partners are working hard to protect owls, whether through increased protection for their habitats or lobbying and education to prevent their persecution. More enlightened landowners, realizing that owls themselves are the farmer’s best natural rodenticide, are managing land for owls, setting aside rough pasture and other key habitat features they require, and providing nest boxes. Meanwhile, owls continue to bring great pleasure to numerous people, from fanatical “owlaholics” who devote their lives to collecting anything that depicts the birds, to hardened “world listers,” who race around the globe trying to tick off as many of its owl species as they can manage. Furthermore, there are those of us who simply love the wild, for whom that haunting voice in the darkness or unexpected flare of silent wings over a moonlit hedgerow represents all that is magical about these most enigmatic of birds.
BIOGEOGRAPHIC REGIONS (ECOZONES)
This map shows the world’s principal biogeographic regions as reflected in chapters one to five of this book. Chapter Six (Oceanic Islands) comprises parts of several other regions.
A note about the selection of owls
This book is a photographic celebration of the world’s owls, and the fifty-three species accounts describe the appearance, distribution, behavior, and something of the cultural associations of each owl. The selection aims to offer a broad picture of owls as a group, with the representatives drawn from most key genera, and covering all continents and all habitats in which they are found. However, it is impossible to strike a perfectly representative balance: the best-known owls—to science and recorded culture—tend to be found in the northern hemisphere, especially in Europe and North America. Northern parts of the world are therefore better represented than some tropical regions, which may have a greater diversity of owls, but offer less information with which to tell their story. The final chapter bucks the trend in that it is not a single biogeographical area. Instead, it comprises a particular suite of shared environmental conditions and challenges to which the owls that live on Oceanic islands, from the Caribbean to the South Pacific, have evolved and adapted in similar ways.
A hovering Barn Owl trains all its senses on prey below.
The Spotted Owl, one of North America’s rarest species, breeds in old-growth forests in the Pacific Northwest.
THE FIRST EUROPEAN SETTLERS TO MAKE IT across the Atlantic could have been forgiven for thinking “New World, same old owls.” Although connected by land to South America, North America shares many features of its natural environment with Europe, including some of its owls.
The explanation lies in geological history. South America was once part of the ancient southern supercontinent Gondwana, splitting from Africa some 135 million years ago, whereas North America was part of the northern continental landmass Laurasia, and was therefore once connected to Europe, sharing its recent glaciation history. Indeed, it was only three million years ago that North and South America came together at the Isthmus of Panama, and they now constitute separate biogeographical regions, each with its own evolutionary history.
Nowadays, North America is the world’s third-largest continent, extending all the way from the Canadian Arctic to southern Mexico and covering approximately 9.5 million square miles (24.7 million sq km). At least thirty-eight