Photo: © Shutterstock.com/Through Christy’s Lens. Spectacled owl: the strong white ‘eyebrows’ emphasise the luminous yellow irises to produce an exaggeratedly penetrating stare.

Bill Naylor introduces the spectacled owl, a beautiful if ferocious predator from the tropical regions of the New World.

OUT of the 55 or so species of owl in South America, the spectacled owl (Pulsatrix perspicillata) is one of the best known, and is exhibited in many of the world’s bird collections, zoos and falconry centres. As early as the
16th century, explorers to tropical South America wrote about the owl with a dark mask that frequented the forest and how its large eyes would stare you out.

Its eyes are no bigger than similar-sized owls, but being set in a dark chocolate-brown facial mask, the bright-orange eyes (lemon-coloured in some subspecies) appear larger than they are. These owls see well in daylight and do not squint in sunlight like some other owls do. Like the other species of Pulsatrix, the contour feathers give the bird a plump and stocky appearance. Its two-tone plumage disrupts the outline of its body shape and, while it is the largest of the Neotropical owls at 51cm (20in) in length, its attractive colouring helps it to blend in with the forest foliage surprisingly well. Males are smaller than females.

The spectacled owl has a habit of perching under overhanging large-leafed plants, probably to avoid getting soaked
in the wet season when the rain is relentless. The feathers on the face are quite long. Its bushy white eyebrows frame the dark masked facial area from which it gets the name spectacled owl. The lores are also white and the large horn-coloured beak develops a greenish tinge as the bird matures. Although largely hidden by heavy feathering, like most South American owls, the talons are large and so, in captivity, spectacled owls require appropriately sized perches.

This species ranges as far north as southern Mexico and occurs mostly in the forested areas of northern and central South America, as well as in Trinidad. Although it sometimes inhabits open country, the spectacled owl prefers the lowland tropical forest and can be found deep in the jungle. It has recently extended its range into plantations and parks in urban areas.

Spectacled owls kept in temperate regions, such as Europe, require heated inside winter quarters, as well as outside flights. Contrary to the belief that owls don’t bathe, if a pond is provided, spectacled owls (and other owl species) will bathe regularly. They will also sunbathe at every opportunity, often lying with wings outstretched on the ground. If the roof is at least partly covered, an aviary pond will provide humidity, which is important for the health and plumage of this tropical species. Pairs are monogamous and don’t need to be separated outside of the breeding season, as is sometimes the practice with owls. Although spectacled owls are usually housed on their own, they are not aggressive to other species. But they are sometimes preyed on by larger raptors in the wild, and can get stressed if housed near to large birds of prey.

In the wild, spectacled owls are opportunistic feeders, as indicated by such names as “crab owl” and “monkey owl”. The variety of species they feed on is extremely wide. While insects and rodents form a major part of their diet, frogs, possums, skunks, squirrels, marmosets and even sloths and bats have been recorded as prey. Birds that have figured on the menu are usually taken when roosting. These include jays, doves, motmots and oropendolas. In habitat where insects abound, these are regularly plucked from vegetation and eaten.

Captive owls have a particular liking for locusts and they are entertaining to watch as they chase after this smaller prey. The main diet in captivity consists of mice, rats and day-old chicks. Usually, the owls remove the heads before swallowing the prey whole and, like all raptors, regurgitate the bones and fur in pellets. The onset of the breeding season commences with the male searching for a suitable tree hollow for nesting. In captivity, they will readily use nest-boxes or wooden barrels.

When the male is satisfied he has a suitable nest site, he calls for a female and is most vocal at dusk and dawn. An interested female will reproduce the call and duet with the male. Her call is distinguished by its higher pitch. The unique voice of this species (pop-pop-pop-pop pop) quickening and decreasing in volume is well documented. In Brazil, “knocking owl” is one of its nicknames. To some, the call sounds like a great spotted woodpecker drumming. These owls also make hawk-like screeching calls that sound like cats fighting. There seems to be lots of variety to their calls. The Duke of Bedford had a pet spectacled owl called Bogey, whose call he likened to the steam whistle of a train approaching.

After mating and when egg-laying is imminent, the male starts to feed the female. Both birds make affectionate mewing and other noises to each other. As with all owls, the eggs are round, white and placed in a nest chamber devoid of nest material. If the first clutch fails, a second is laid without delay. The female alone incubates normally two, more rarely three, eggs.

Aviculturist Glen Holland gathered information from numerous zoos in Europe and North America, and found that the incubation period in captivity can vary from 28 to 58 days. By contrast, eggs hatched in an incubator can take from
36 up to 80 days to hatch. The owlets, predominantly white with a dark mask, are often described as a negative of their parents. They go through a successive series of moults over three to five years before they assume full adult plumage. This process seems to take longer in captivity than it does in the wild. As is usual among raptors, frequently only the strongest owlet survives.

Upon hatching, these owls have a thin coating of natal down. After a fortnight, they develop a second covering of down. Adult plumage may not be fully acquired until they are five years of age. Breeding can commence at two years old; consequently, these birds often breed while in immature plumage. This led to early naturalists either assuming the female spectacled owl had different plumage, or immature and adults were two different species. Immature birds were often referred to as “masked owls”. Fledging takes place at six to eight weeks. As with a lot of owls, they venture out from the nest cavity at around five weeks old still covered in down, but return to the nest cavity to be fed and to roost. They can remain with the parents for as long as one year. Spectacled owls can live for up to 35 years in the wild and have survived for more than 20 years in captivity. These birds have been exhibited in a number of British zoos. Chester Zoo, along with Baltimore Zoo in the US, have breeding programmes for this species.

In South America, bird smugglers often target spectacled owls and, although their habitat is not under immediate threat, in some areas the populations are decreasing. Fortunately, the pool of captive birds is well established.

Bill Naylor has enjoyed a 40-year career in ornithology and aviculture.

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