Wednesday, Sep 17, 2014

Plain-tailed Nighthawks

Plain-tailed Nighthawk (Nyctiprogne vielliardi)

Nightjars

The Plain-tailed Nighthawk (Nyctiprogne vielliardi) - also known as Bahia Nighthawk, Bahian Nighthawk or Caatinga Nighthawk - is a South American nightjar that was only described in 1994.

It is a member of the nightjar or goatsucker family, named such as they were once believed to drink a nanny goat's milk during the night. In the past, night-flying birds - such as the nightjars - were suspected of witchery.

Their cryptic appearance blends perfectly into their habitat and they are very difficult to spot during the daytime, when they are usually hidden away sleeping. Their presence is most often made known by their loud calls given at dusk.

It was given the name "Plain-tailed Nighthawk" as it lacks any tail-band, which distinguishes it from another Brazilian endemic - the closely related Band-tailed Nighthawk (Nyctiprogne leucopyga). The other names "Bahia Nighthawk" and "Caatinga Nighthawk" refer to its geographic profile; although somewhat inappropriately so, as its range is not confined to the state of Bahia and the Caatinga habitat occurs only in part of its range.


Alternate (Global) Names

Chinese: 巴伊亚夜鹰 ... Czech: lelek bahijský ... German: Bahianachtschwalbe ... Estonian: kaatinga-videvikusorr ... Finnish: ruskohaukkakehrääjä ... French: Engoulevent de Bahia, Engoulevent de Vielliard, Engoulevent du Bahia ... Italian: Succiacapre della caatinga ... Norwegian: Kastanjenatthauk ... Portuguese: bacurau-do-São- Francisco, Bacurau-do-São-Francisco ... Russian: Бахиский сумеречный козодой ... Slovak: súmracník hnedý ... Spanish: Añapero de Bahía ... Swedish: Caatinganattskärra


Distribution / Range

The Plain-tailed Nighthawks have a small range are currently known only from two localities along the rio São Francisco and immediately adjacent tributaries in Bahia and in the state of Minas Gerais in central Brazil.

This species is classified as Near Threatened based on the loss of riverine forest and scrub within its range.


Behavior

It is crepuscular (active at dawn and dusk) and nocturnal (active at night). Even though there is only little information available on this newly identified species, its behavior is believed to be similar to that of the related Band-tailed Nighthawk.

At dusk, they have been observed feeding high above the river in flocks of up to 20 individuals. During the daytime, they often roost under riverside bushes and the ground.


Description

The adult plumage is dark with brown, grey and white patterning on the upperparts and breast; the long upperwings are black. The tail is dark without any barring, which distinguishes it from the related Band-tailed Nighthawk. The under plumage is buffy.


Breeding / Nesting

The male establishes his territory and sings at night to keep rivals away and at the same time to attract a female.

Nightjars don't actually construct a nest, as most other bird species do. They simply place the eggs in an unlined depression on the ground.

Nesting appears to be timed in such a way that the moon is more than half full at the time they are feeding their young - likely as the additional light during the night facilitates caring for the young and foraging for food.

The female may lay one to two eggs (mostly two) that are whitish or creamy in color, with brown and grey spots or blotches.

During the day, the incubation of the eggs is undertaken by the female, while both parents share the incubation at night. The incubation period is about 19 to 21 days.

The hatchlings are covered in down and generally move apart shortly after hatching. Within 24 hours of hatching, they are capable of short-distance movements. The male takes the responsibility for protecting the nest. He usually remains near the nest and defends it against intruders. He is often observed hovering near the nest keeping his body in a nearly vertical position and his tail spread to show off his white barring. The parents communicate with their chicks with soft clucking sounds to which their young respond.

The parents feed the chicks regurgitated food (mostly insects), and they continue to brood them until fledging. The fledglings leave the nest when they are about 20 to 21 days old.

Provided conditions are favorable, the female may lay a second clutch close to the first and while she is incubating the new set of eggs. If this happens, the male continues to care for the young from the first brood.


They have developed several behavioral adaptations to minimize predation:

    • Their mostly nocturnal (night) lifestyle reduces the likelihood of being detected by daytime predators. During the daytime, they typically sleep on the ground where they are perfectly camouflaged by their "earthy" colored plumage. They almost always change their roost sites on a daily basis.

    • When nesting, they sit quietly on the eggs, minimizing any movements that could get them detected.

    • If an intruder does get close to the nest, the parents may try to lead them away by first flushing off the nest and when landing feigning injury as they lead the potential thread away from the nest. While the parent performs this distraction display, the young may scatter and freeze.

    • The parent who is not incubating the eggs or brooding the young will roost away from the nesting area.

    • They may also move the eggs or young to prevent them from being preyed upon.

    • Nightjars avoid voicing when they hear the calls made by predatory nocturnal animals, such as owls.

The Feeding Habits of Nightjars / Nighthawks

Species Research by Sibylle Johnson

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