The nightjar

THE NIGHTJAR
Close encounter with the ghost of the Nure
by Marco Mastrorilli (Noctua)
The river Nure flowing across the plain between Ponte dell’Olio and Podenzano has environmental characteristics that make it the ideal “scenario” to shelter a real protagonist of this riparian ecosystem, a creature that we can call the "ghost of the river": the nightjar, known in Italian as the succiacapre or goatsucker.
Whenever the name of this bird is mentioned it arouses reactions varying from outright hilarity to amusement to curiosity. However, to reveal the origins of such a curious name, we must take a great leap back into the past, to discover that the behaviour of the nightjar aroused the curiosity also of ancient populations.
Claudius Aelianus (Rome, 2nd-3rd century AD), a sort of naturalist populariser of the time, wrote, “ [...] it despises small birds and attacks goats with great violence, whirling down in flight on their udders and, without fearing punishment by the herd of the flock, sucks the milk, [...]”.
Pliny the Elder too described it in his celebrated Historia Naturalis, with even more audacious remarks, “ [...] The behaviour of birds is equally varied, especially as regards food. A bird that looks much like a large blackbird is the nightjar, a nocturnal predator. During the day it is blind. At night it enters the sheep-pens and flies down to fix on to the goats' udders to suck their milk. After this violence the udder is dry and the goats which have been milked in this way become blind. [...]”
These ancient writings, linked to traditions going back thousands of years, reveal the source of the really odd name this bird carries, a night bird that nowadays is quite rare and therefore adds a certain value to a territory. Today, for purposes of conservation, the nightjar is considered a species of community interest because all over Europe there is a contraction of the ecosystems suited to its habitat and a generalised decline in numbers, seen in Western Europe since 1900.
From a taxonomic point of view, the nightjar, scientific name Caprimulgus europeaus, is included in the Caprimulgiformes, a particular order that includes 89 species on different continents. The nightjar is one of the strangest and most unusual birds in the province of Piacenza but it is not difficult to recognise. Its behaviour and its peculiar call help recognition, even under conditions when observation is difficult. Its size is similar to that of the blackbird Turdus merula, its weight varying between 45 and 95 grams, but its posture when perching and its flight are unmistakeable. When it is perched, the nightjar has short legs and remains "crouched" on the ground with a central baricentre, so that it is easy to identify an indivdual even in shadow or at dawn or dusk.
Then, if the nightjar is observed in flight, recognition is assisted because this species has a flight pattern that is quite inimitable thanks to its irregularity, as the bird flits here and there. Its silhouette in flight recalls the direction of the cuckoo's flight, but its energy, its rhythm and the irregularity of its evolutions, dictated by trophic needs, make it unmistakeable and evoke the image of a ghost because of its unexpected appearances and its mysterious flight. Its plumage is similar to many cryptic species, such as the horned owl or the wryneck, but its habits mean it lives primarily on the ground and its camouflage is therefore a perfect adaptation to the environment where it lives.
By the Nure it is extremely difficult to see it during the day but in the evening its call is really frequent. Everywhere in the world the nightjar adopts reddish, greyish, yellow-brownish colouring depending on its habitat, whether this is a desert, a garrigue, an equatorial forest or the uncultivated areas along the Nure. However, the European nightjar exhibits an astonishing sexual dimorphism in flight: the males reveal showy white stripes on some remiges and on the outermost rectrices (flight feathers).
The nightjar is an insectivore which, as we have seen, feeds in flight, capturing insects like bats do, but their diet is varied and they can eat insects off the ground, rocks and even tree trunks, especially when they are feeding their young and need to find larger prey. Studies on the trophic system of this species are not simple but they have been found to prey on orthoptera, coleoptera, lepidoptera, diptera, hymenoptera and even on occasion arachnida. Their trophic specialisation makes them migratory birds which nest in Italy, so that they can be seen in the Nure valley only from late April until the middle of September.
At dusk the uncultivated areas along the Nure provide space for the aerial acrobatics and the calls of the nightjars, which emit repeated trills that are quite particular. This is known as “churring”, to many the strangest among all the bird songs of Europe!

Acoustic identikit of the ghost of the Nure!
The call of the male during the mating season is characterised by extenuated monologues formed of these prolonged trills that end with a pleasing though surprising "clap" produced by beating the wings, which ornithologists have termed simply "applause"!

The nightjar is certainly one of the most important presences in the Nure valley, a spontaneous colonisation favoured by the abundance of insects that live along the banks of this still little-known river .