The Night Birds of Tobago

Faraaz Abdool has taken up residence within the Northeast Tobago Man and the Biosphere Reserve to document the flora and fauna. Here are some of the creatures he sees after dark.  Photos by Faraaz Abdool

Humans have evolved enthralled and terrified of the night. The animals which depend on the world devoid of light seem alien to us. We are predominantly visual creatures. Numerous legends abound, almost always involving some aspect of the perceivable combined with a healthy helping of the imperceptible. Many nocturnal animals have been wrongfully accused, becoming victims of fearful superstitions. Some view them as harbingers of death and misfortune, others believe they are incarnations of evil spirits. As a result, they are often persecuted and chased; and may even be killed on sight.

Nocturnal animals are carefully and deliberately adapted to survive in a world that is the opposite of what we are accustomed to. While most of us sleep at night and wake during the day, these animals are awake in the night. Their physiology and appearance are specially tailored to suit. In a world of little to no light, their eyes are adapted to maximize visual acuity and light-gathering ability. This translates to exceptionally large eyes. Many nocturnal animals also have oversized ears as sound is critical for mapping their environment. Others have long whiskers to feel their way in the darkness. Most of these adaptations would prove useless for a diurnal animal, especially one that is heavily dependent on sight.

A White-tailed Nightjar sits on its preferred perch as darkness falls. Photo by Faraaz Abdool

 

Nocturnal animals must also conceal themselves during their daytime rest. To ensure that they remain undisturbed, many animals hide in burrows in the earth or within large trees, out of sight and reach of any potential predators. For others, however, hiding in plain sight is what they do best. They are cryptically patterned with various shades of brown, cream, rufous, and other natural tones in such a way that renders them invisible against the appropriate background.

There are many species of birds that can operate at night – but these are distinct from those that are strictly nocturnal. Sometimes we may hear the high-pitched calls of Southern Lapwings or Black-bellied Whistling Ducks as they feed or fly overhead during hours of darkness, but both species are also well adapted to diurnal living. On Tobago, there are four bona fide nocturnal birds.

The most common of these is the diminutive White-tailed Nightjar. These birds emerge at night to feed. The way they do it is effective and efficient: select a preferred perch where there are insects flying around, and then make quick, short flights to grab one on the wing. Their wide mouths are surrounded by stiff whiskers called rictal bristles – which are basically central stems of feathers. Studies are still being undertaken to properly understand the evolution and function of rictal bristles, and there are several theories.

 

Huge eyes help the Common Potoo track its prey throughout the night. Photo by Faraaz Abdool

The family of nightjars has an almost worldwide distribution, with representatives on every major continent except Antarctica. Due to their historic coexistence with human habitation the world over, some truly fantastical stories have been spoken about this family, most notable of which is the legend of nightjars drinking the milk of goats. This ancient superstition has led to their colloquial name of “goatsucker.”

Another night bird with a worldwide distribution is the instantly recognizable Barn Owl. This relatively large owl is a common resident of open areas and tends to spend the daylight hours comfortably asleep in abandoned structures. Before there were barns, Barn Owls would roost in caves and other natural hollows. The heart-shaped face of this owl is one of the more familiar avian faces, its design is in fact in relation to its hearing and not merely aesthetics. This facial disk funnels even the faintest sounds to its ears such that it can detect the movement of prey in complete darkness. Barn Owls’ feathers have a subtle fraying to the edges which eliminates the sound of flight. This silent approach allows the Barn Owl to continually listen for hidden prey while keeping their intended victims literally in the dark.

It is important to let nocturnal birds roost in peace during the day and be left unbothered. The raised foot of this Barn Owl indicates it is relaxed. Photo by Faraaz Abdool

Striped Owls found on Tobago are unique to the island and a major attraction for local and foreign birders. Photo by Faraaz Abdool

 

Tobago’s only other resident owl is the infrequently encountered Striped Owl. This medium-sized, richly patterned owl is poorly known despite a wide distribution across the Neotropics. Even more surprisingly, it often occupies human-altered habitat such as open fields and forest clearings where it preys primarily on rodents. In fact, it often nests on the ground! This attribute of the species may lead to it eventually expanding its range as more areas are deforested, albeit at the expense of other more forest-dependent species. Striped Owls on Tobago are an endemic subspecies to the island. Further studies are necessary to determine the population status of this incredible bird.

The enigmatic Common Potoo completes this set of four. This mysterious bird can hide itself in plain sight so perfectly that most of us are unable to discern a potoo from a branch. Its cryptic plumage coupled with its habit of holding its elongated body completely motionless render it invisible to the untrained eye. It can even change how it holds its feathers to mirror the thickness of its perch. At night it hunts for flying insects mainly by sight, its sensitive eyes finely attuned to operating in near darkness.

The Common Potoo’s vocalization is a series of three to five deliberate, drawn-out, descending notes with such a mournful quality that locally it is also called “poor-me-one.” The White-tailed Nightjar possesses a significantly more cheerful sounding, high-pitched whistle. Neither of the owls asks “who?” as commonly believed: the Barn Owl utters a shrill shriek; the Striped Owl can bark like a dog. The sounds these birds make are key in not only being able to identify the species but can also aid in dispelling myths surrounding these misunderstood denizens of the night. We can’t see well at night, but we can listen!