Owl

by Desmond Morris

  The excitement is contagious, with many new birds arriving and performing the mobbing display without even seeing the owl that is causing the commotion. They witness the behaviour of the other small mobbers and simply follow suit. They become so excited during this gang warfare that humans can approach them much more closely than at other times. And their arousal is so intense that if the owl finally departs they will still go on mobbing for a long time afterwards, as though they cannot calm down to a normal level of activity until some considerable time has passed.

  The beleaguered owl gives the appearance of finding the whole encounter highly distasteful and confusing. Its bearing suggests that it is irritated and jarred by what is taking place around it. It becomes increasingly ill at ease until eventually the din and the intrusions become too much for it and it flaps off to find a quieter spot somewhere else. And this, of course, is the function of the combined display onslaught. The owl will not forget the ordeal and may in future avoid that particular district. For the local small birds this is a huge advantage.

  The question remains as to how the small birds identify the owl. What are the special features that trigger such a powerful response? Field tests using stuffed owls and wooden dummies have established that the important features that make an owl an owl are: a big head, a short tail, solid contours, brown or grey colouring, a patterned surface with spots or streaks, a beak and frontally directed eyes. The more of these properties a dummy possesses the more strongly it is mobbed, but it seems to make little difference whether the object is a stuffed owl with real plumage or an owl-shaped piece of painted wood. If the key elements of owlness are absent, or only a few are present, the small birds show some curiosity about the dummy but are not stimulated to perform the full mobbing response.

  One particular owl quality that is sufficient by itself to attract mobbing birds is the characteristic hooting sound it makes. This is a fact that was known all too well to plumage hunters in Trinidad, back in the days when hummingbird feathers were fashionable costume accessories. They discovered that simply by imitating the hooting of the local owls they could draw the unfortunate hummingbirds towards them and to their deaths.

  CONSERVATION

  After centuries of persecution, owls are at last being appreciated for the dramatically wonderful birds that they are. There are many excellent owl protection and conservation organizations, and careful studies have been made to assess the surviving populations of the different species. Of the approximately 200 species of owls alive today, conservationists have listed eleven as endangered and a further six as critically endangered (marked * on table overleaf). The species in serious trouble are shown overleaf.

  The cause is always much the same – loss of habitat. Most owls need forests and forests are being decimated all over the world. For some species the long-term future looks bleak. The other threat is that pesticides are being widely employed to reduce the numbers of the kind of animals that owls need for their diet. And in a few backward regions there are still dark superstitions about owls that see them destroyed as evil spirits.

  Public concern about endangered owls did, however, receive a boost from Hollywood in 2006 with the release of a feature film called hoot. Described as an ‘eco-thriller’, the story is about a group of teenagers who take on Florida land developers whose bulldozers are threatening the habitat of the local burrowing owls. The dramatic poster for the film shows the teenagers standing defiantly between an owl in its burrow and an approaching bulldozer. The fact that the Hollywood film industry considers such a plotline commercially viable is good news for the conservation of owls.

  Another cause for celebration is that of the 200 species of owls, over 180 are listed in the conservation category of ‘Least Concern’. Some of them have almost unassailable populations. The great horned owl, for example, has an estimated world population of no fewer than 5,300,000. And the barn owl almost matches it, with 4,900,000. The owls, with their special, nocturnal solution to the problem of survival, have always been a globally successful family of birds and with figures like these it would seem that they are here to stay.

  Poster for feature film HOOT, released May 2006.

  Eurasian eagle owl (Bubo bubo).

  10 Unusual Owls

  As a whole the owls are a remarkably uniform group of birds. They may vary a little from species to species in their plumage colouring, their facial markings and their ear-tufts, but their way of life as nocturnal hunters seems to suit a rather rigid, basic owl design and aberrant species are a rarity. Despite this there are a few that do deserve special mention because they have strayed from this typical owl form in one direction or another. Some have become unusually large, some exceptionally small, and some have descended from the trees to inhabit underground burrows. Finally, a recently extinct owl was reputed to have lost the power of flight and has gained a rather strange legendary status.

  THE GIANT OWL

  The most dramatic owl in the world is the Eurasian eagle owl. Weighing 3,000 gm (61/2 lb), with a body up to 72 cm (28 inches) long, and with a staggering wing-span of as much as 175 cm (69 inches) it is a giant among owls and a feared predator. Its diet includes the usual rodents but it also, surprisingly, hunts other owls. This is very much a one-way relationship – no other owl would ever dare to attack an eagle owl. It also preys upon diurnal birds of prey such as hawks, harriers, kites, buzzards, falcons and even the occasional eagle. In fact its diet is enormously varied. In addition to birds of prey it has also been known to kill and eat ducks, coots, grebes, grouse, partridges, quail, doves, pigeons, gulls, waders, woodpeckers, crows, jackdaws, jays, magpies, nutcrackers, larks, thrushes, starlings, swifts, swallows, cormorant, herons, bitterns, bustards, cranes and even ravens. It is the same with mammals. In addition to rats, mice and voles it also devours rabbits, hares, deer fawns, chamois and ibex kids, wild sheep and their lambs, squirrels, stoats, weasels, mink, martens, foxes, bats, domestic cats, moles, shrews and hedgehogs. Clearly, nothing is safe when the great eagle owl is on the prowl and no owl in the world has such an impressively varied diet.

  Most owls would be frightened of a large crowd of cheering, shouting people, but to one magnificent eagle owl they meant nothing. In 2007 a major international football match was taking place between Belgium and Finland in the national stadium in Helsinki. In the middle of the game the giant bird swooped down on the players and landed on the pitch. The referee stopped play and took the players off, to await the owl’s departure. To his relief he saw the great bird spread its wings and fly up as if to bid farewell to the noisy crowd. Instead it settled majestically on the cross-bar of one of the goals, and rotated its head this way and that, taking in the human spectacle all around it. Seemingly puzzled rather than scared, it then took off again. The crowds cheers turned to laughter when, instead of fleeing the scene it settled itself on the goal at the other end of the stadium and proceeded to stare at the opposing football fans amassed there. Eventually it did depart and the game was resumed, but its lordly presence at the stadium revealed two things. First, the Eurasian eagle owl feared no man and, second, no man was brave enough to attempt to drive it away.

  Since this incident, Finland’s national football team has become known as the Huuhkajat, Finnish for Eurasian eagle owls, and the owl itself was named Helsinki Citizen of the Year in December 2007. It was given the name of Bubi and an investigation revealed that it was an urbanized owl. It had been using the A-stand of the arena as a regular roosting spot for some time and was obviously upset on this occasion to find its personal territory occupied by thousands of cheering football fans.

  A more recent claim to fame is that the eagle owl is the species that appears as the family owl of the Malfoys in the Harry Potter stories by J. K. Rowling.

  This is indeed the king of owls, and it seems somehow fitting that these great birds employ the ancient Step Pyramid at Saqqara as an annual breeding site. A sad footnote, however, is that this super-owl is falling prey to human persecution a
nd its numbers are dwindling. Its fearless attitude to mankind has not helped it in this respect, and it seems to be unusually susceptible to collisions with road and rail traffic and especially to overhead wires and power lines.

  THE SMALLEST OWL

  The smallest owl in the world is the tiny elf owl that nests in large cacti in Mexico and the southern states of the USA. Weighing 40 gm (11/2 oz) and with a body length of only 14 cm (51/2 inches) it is not big enough to feast on small mammals or birds. Instead it enjoys a diet of large insects such as locusts, grasshoppers and crickets. It also eats beetles, moths, spiders, centipedes and the occasional scorpion. It takes large insects when they are settled on plants but is also capable of catching them in mid-air, either in its talons or in its beak. When living near to human habitation, the hunting elf owl is known to exploit the swarms of night-flying insects that are attracted to outside electric lights.

  Elf owl (Micrathene whitneyi), the smallest owl, here nesting in cactus.

  Unusually for an owl, it does not have silent flight, presumably having no need for that degree of stealth when hunting its invertebrate prey. Another unusual feature is that it possesses only ten tail feathers, when all other owls have twelve. Vocally, it whimpers, whines, yips and barks like a young puppy. The males can be aggressive in defence of their nests but the females are more likely to feign death with closed eyes and an apparently lifeless body. During the day the elf owl employs a special hiding strategy, remaining immobile in an erect posture with its feathers pressed close to it body, one wing drawn forward, and its facial disc narrowed. In this way it mimics a broken branch or a stump of wood and avoids detection.

  THE BURROWING OWL

  The strange little burrowing owls, with their spindly legs, bright yellow eyes and an unusually vertical posture, are found throughout the whole length of the Americas from the short-grass prairies of Canada in the north, to the pampas of Argentina and Chile in the far south. In addition to these grasslands they are also encountered in desert and semi-desert regions and today even in human suburbs, including golf courses and airports.

  The burrowing owl has several very un-owl-like features. Anatomically, its legs look more like those of a chicken than of an owl. A typical owl sits on a branch with only its feet showing, its legs mostly hidden by its lower plumage. The burrowing owl, spending nearly all its time either on the ground or below ground level, has unusually long legs, most of which are fully visible. Its behaviour is also very odd for a member of the owl family. Instead of nesting or roosting high above ground, safely out of the reach of ground-dwelling predators, the burrowing owl, as its name suggests, makes its home in underground tunnels, sometimes dug by itself, but more often borrowed from the warrens of large rodents such as prairie dogs or viscachas.

  A burrowing owl at the entrance to a burrow.

  The ground squirrels known as prairie dogs used to exist in vast numbers in the Americas before human populations began to proliferate and interfere with the long-established balance of nature. Even as late as the early twentieth century some colonies had populations of as many as a hundred million individuals. Their burrow systems, extending for miles in all directions, provided the perfect habitat for the little burrowing owls and they too flourished. When the rodents were exterminated as pests over huge areas of the continent the owl populations disappeared with them and today they are far less common than in previous centuries.

  The social relations between the owls and the rodents are complicated. In some regions the two populations live side by side, more or less ignoring one another. In others there is considerable hostility. There is an old folk legend suggesting that the burrowing owls, rodents and rattlesnakes all live together in harmony and share the same burrows, but this is not the case. The owls drive out the rodents when they take over a burrow and the rattlesnakes are only there as predators.

  Burrowing owls use their underground tunnels both for sleeping and for nesting. The nests are unusual, being lined with the dung of large grazing mammals. This is a refinement not found with typical owls and it aids the nestlings of the burrowing owl by masking their odour and effectively concealing them from scent-hunting predators. This is important because, being reared in underground tunnels, the nestlings are unusually vulnerable to nocturnal mammalian predators such as weasels, opossums and badgers. If the odour-masking fails to work and the predator comes close to the nest the young owls have one final strategy left with which to protect themselves. They have evolved a special alarm call that combines hissing noises and rattling sounds – mimicking a venomous rattlesnake. Weasels and other small carnivores will think twice about getting any closer in the dark of the tunnel and may then retreat. Of course, if the predator happens to be a rattlesnake this strategy fails.

  Burrowing owls are active by day as well as at dawn and dusk and are the least nocturnal of all owls. They even hunt for lizards and large insects in the bright noonday sun. In keeping with their preference for living at a low level they sometimes chase their prey across the ground. In addition to animal foods, burrowing owls, uniquely among members of their family, also devour fruits and seeds. In some regions they favour cacti fruit such as those of the prickly pear.

  Typical owls are never seen in colonies or large groups, and here again the burrowing owls are atypical, because they can often be observed roosting or nesting in groups of ten pairs or more. Several families may gather together outside their nesting burrows in regions where the populations are at a high level, making this a very unusual kind of owl indeed.

  THE FLIGHTLESS OWL

  One of the most mysterious of all owls is the extinct Bahaman great owl (Tyto pollens), known only from sub-fossils. Also referred to as the Andros Island barn owl or the Bahaman barn owl, this extinct species was a relative of today’s common barn owl. A giant among owls it was said to stand 1 metre (39 inches) tall and to have lost the power of flight. It lived in the old pine forests of Andros Island, the largest of the Bahamas, and nested in burrows. It managed to survive the arrival of Europeans in the sixteenth century until they cut down its forests, when it quickly disappeared.

  It gave rise to a local legend about a malicious bird-like dwarf with an owl-like face, glowing red eyes, a head that could rotate in any direction, three fingers, three toes and a tail that was used to hang from trees. The early settlers on the island told wild stories about this mischievous nocturnal imp, called a Chickcharnie, claiming that it built its nest by joining two pine trees together at the top. Anyone sightseeing on Andros is advised to carry flowers or bright bits of cloth to charm these troublesome beings, and not to molest them or sneer at them. If you respect them you will be blessed with good luck for the rest of your life, if not your head will turn completely around and you will suffer terrible misfortune. Having exterminated the real bird the locals now seem intent on protecting its ghost.

  Bizarrely, the Chickcharnie is said to have been responsible for World War II. The story is told that, as a young man, Neville Chamberlain, who would later become the British prime minister, was chopping down trees on Andros Island to make way for a plantation when he came across a Chickcharnie nest, high in the pines. His local workmen refused to touch it and fled in terror, but he ignored their warnings and chopped down the trees himself, destroying the nest and bringing on himself a lifetime curse. It was this curse that led to his notorious failure at Munich which led to the outbreak of World War II. However one looks at it, this is quite an achievement for an extinct owl.

  Appendix: Classification of Owls

  One of the first attempts to classify owls scientifically is that of Pliny in AD77. In Book X of his Natural History he identifies three species of owls: the little owl, the eagle owl and the screech owl. By the sixteenth century Conrad Gesner (1560) had increased this number to four,1 and by the seventeenth century, in the monumental 13-volume Natural History of Ulysses Aldrovandus, it had risen to eleven, all wonderfully illustrated in large woodcuts.2 This marks the start of a serious, scientifi
c attempt to organize and illustrate the owl species and to comment on their differences, but it was not until the nineteenth century that zoologists began to venture into the more obscure parts of the world to locate and collect the specimens that would soon fill the basements of the great natural history museums. During the twentieth century this process was energetically continued until it became increasingly difficult for even the most intrepid exploring scientist to locate a new large species of any animal. However, this does still occasionally happen and even within the last few years a new owl species has been discovered.

  Today authorities vary considerably in their opinions concerning exactly how many species of owls there are. Some accept as few as 150, while others list as many as 220. One of the main reasons for this huge discrepancy is that many owls live on small islands where they develop slight differences from their close relatives on the nearby mainland. It then becomes a matter of taste as to whether you consider one of these isolated populations of owls as a distinct species or not. For example, there is a kind of barn owl that is found on the Andaman Islands in the Indian Ocean. It is significantly smaller than the mainland form, but because the two never encounter one another in the wild it is impossible to tell whether, if they did meet, they would freely interbreed or remain completely separate. So one can only guess as to whether they are genuinely distinct species or not. If you happen to be an objective zoologist you are likely to lump the two together as races of the same species, but if instead you are a passionate conservationist you are more likely to view the island form as a distinct and therefore very rare species that needs urgent protection.