NIGHT-SINGING NIGHTINGALES

The nightingale is justly praised for its tuneful singing, but it cannot excel in all things: despite its wonderfully varied musical performance, it is an unobtrusive, dull brown bird, here for a short breeding season spent hiding in the thickets.

The nightingale combines the extremes of delightfully melodious singing and a generally uniform, unremarkable plumage. It is about half way in size between the robin and the song thrush, two fellow members of the thrush family. In its general posture the nightingale is comparable to these two birds. Its plumage, however, is considerably less colourful than that of other members of the thrush family, being chestnut-brown all over the upperparts and paling to a rufous fawn beneath.

Most nightingales breed to the south of a line between the Severn and the Humber, preferring habitats with a well-developed and dense undergrowth. Thus most are found in woodland areas, usually of deciduous trees and very often of oak, with the mature trees widely spaced. Towards the north-western fringe of this breeding range, the wooded slopes of river valleys are favoured.

Over the last few centuries, the distribution of the nightingale right across Europe has contracted considerably. Possibly this is partly due to wholesale trapping (particularly on the Continent) of nightingales for caging as song birds or, even more unpleasantly, for sale in delicatessens. Though this does still occur, it seems more likely that the major factor in the decline is the loss of the appropriate type of deciduous woodland. This is due both to modern farming, with its demands for full land usage and increased field sizes, and to modern forestry practice, in which broad-leaved woodland is replaced by dense plantations of conifers.

Watching for nightingales

Generally, nightingales are shy, rarely venturing into the open. So for many of us this is a bird far more often heard than seen. Considerable patience, and quiet watching from semi-concealment in an area with several nightingale pairs – and preferably with some paths to provide open ground-is required to obtain even fleeting glimpses. If you are lucky, a male nightingale may choose to sing from a perch in your line of sight, head thrown slightly back, throat bulging, giving you a chance to see the performance as well as hear it.

More often, apart from the song, much of what you hear in the undergrowth is the surprisingly varied repertoire of ‘chack’ and ‘churr’ noises with which the nightingale deters intruders from approaching its place of concealment. You may also hear the soft ‘weet’ call that the pair use to keep in contact.

Our best night singer

The voice of the nightingale, heard solo at dead of night, comes through the clear, warm early summer air as one of the most delightful bird songs in the world. The song period is, however, short, generally spanning the second half of May and the month of June, but rarely continuing as late as July.

For quality, range and versatility the nightingale’s voice cannot be matched, even among British birds with their exceptionally rich songs. Part of the enjoyment stems from the sheer variety-from throaty chuckles to far-carrying whistles-and part from the quality of the tonal range, from rich, deep phrases to the purest of treble-like trills and flourishes.

Special adaptations

In the shelter of its habitat of thick undergrowth, the nightingale spends much of its time concealed from view. It is one of the more terrestrial birds in the thrush family. Strong legs and large eyes are adaptations to this mode of life, as also is the beak. Though not so stout as the conical beaks of the finches, nor so fine as that of insect-eaters such as the pied wagtail, the well pointed but strong beak of the nightingale allows it to tackle most soil and litter-dwelling invertebrates. These range from tiny insects and spiders to caterpillars and worms. The beak is also suited to feeding on berries as they become available later in the month. At this time they are invaluable as a sugar-rich resource to help the nightingale put on fat as a fuel reserve for the long migration south.

The breeding season

Nightingales perform a pairing display which is rarely seen because of the dense cover in which it takes place. It involves much ritualised posturing, with wings drooping and fluttering, and with tail fanned. After the display, the nest is built low in the vegetation or, quite commonly, on the ground. It is always well concealed from disturbance by humans and large predatory mammals or birds, although it is not safe from such predators as weasels or mice. The nest is basically constructed of dead leaves. Usually those found lying nearby. Those found in England are most often held together by fine twigs or stout grasses. The lining of the cup is of fine grasses and hair, and the normal clutch is four or five (occasionally six). The eggs are brown, so densely speckled as to appear almost uniformly coloured. Because of their early departure on migration, there is normally time for just a single brood each season.

Long-distance migrants

Nightingales desert their breeding woods from late July onwards. Ringing results indicate that most nightingales cross the Mediterranean in autumn and fly over the western margins of the Sahara Desert. Their wintering areas are in tropical West Africa, as with many other migrants. Individual breeding birds often return to precisely the same patch of dense cover in successive years, for unless the site has been cleared by man, nightingales keep to their traditional nesting grounds.

Mammals of deciduous woodlands In keeping with its status as the most elaborate habitat we have in Britain, deciduous woodland supports the most diverse community of mammals. Most of them lead secretive lives, foraging under cover of darkness, but with practice we can interpret much of their daily lives by observing their tracks, runways, droppings and the leftovers from their meals. Unlike birds, woodland mammals live in a largely two-dimensional plane and, though some mice and voles are accomplished climbers, only squirrels and, of course, the bats are found at any height. Mammals are also creatures of habit, their comings and goings typically following familiar, well-worn paths at regular times of day. Although their hearing, and especially their sense of smell, are acute, their vision is at best not exceptional and at worse (as in shrews and badgers) quite poor, so we can, with care, observe them quite closely without being detected.

The mammal community of woodland is a good illustration of a food ‘pyramid’, with a broad base of herbivorous and insectivorous rodents, at relatively high density, serving as prey species for top carnivores such as the weasel and stoat which defend large territories and are thus thinly spread. Typical of the small prey species are the wood mouse and bank vole. Both supplement a diet of fruits, nuts, seeds and the green parts of plants with a certain amount of insect food. Shrews devour a wide variety of invertebrates and are the arch exploiters of the rich earthworm population that lurks beneath the leaf litter, a resource also tapped by hedgehogs, moles, foxes and badgers. It is not hard to see why, in this hazardous environment, the small mammals have sought safety by confining their activity to the hours of darkness-and many of their predators have had to follow suit.

Woodland deer-the fallow, roe and introduced muntjac – though largely exempt from this food chain, are also mostly dusk foragers, an adaptation to bygone times when they too had natural predators. Though most woodland mammals hunt throughout the year, a minority-the hedgehog, dormouse and the bats-hibernate over winter, while some others, such as the badger, merely become less active.

15. November 2011 by admin
Categories: Ecology/Habitat, General Info, Uncategorized | Tags: , , , , , , , , , , , | Comments Off on NIGHT-SINGING NIGHTINGALES

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