This article was originally published in the Journal of the Wildlife Sound Recording Society Vol3 No6 Spring 1980
Natural history sound recordists must he opportunists to have real success at their craft, Many favourite subjects for recording normally become vocal at dusk or in the course of the night; nightjars, badgers and different owl species are obvious examples. But, when the recordist, microphone poised, is anticipating sound from a chosen subject, so often it is a different species of mammal or bird which calls. Speaking for myself, the planned recording of a pre-selected species, whether by day or by night, is doomed to failure or at least to a partial alteration of the programme, Nevertheless, unexpected sounds may be produced at any time although it is during the hours of darkness, when fewer species are active, that most surprise noises seem to arise.
Thus, where foxes are common, it is not unusual,to bear the clucking alarm of blackbirds in the middle of the night, especially during springtime and summer. On more than one occasion I have peered in the direction of a blackbird's chatter at 3a.m. and, eventually, I have become aware of the shadowy form of a fox moving round the base of the roosting er nest tree, These night calls are more likely to be given if the blackbird has young in the nest, or if young have newly flown. In gardens and orchards, song thrushes will alarm in the same way as blackbirds under similar conditions.
But, more dramatic. and startling than the alarm of song thrushes or blackbirds is the hard, rasping churr of mistle thrushes; heard in the stillness of the night this unexpectedly loud can be quit,e frightening If one watches carefully, utilising glimmers of moonlight or street lighting, then usually a lurking cat or fox can be seen.
Apart from alarm calls, the songs of some birds may be heard at night, especially in suburban areas where there are bright road lights. The obvious example is the robin and, particularly in winter and early spring, I often hear the high-pitched, warbling phrases of this bird during the early hours in town gardens. Less frequently, song thrushes will, also sing at night; in well-illuminated urban parks the familiar strident, musical notes may well be heard at midnight or soon afterwards. Usually, this nocturnal song is not continued for long periods of time, and occurs mainly in April or May. Besides its song, another characteristic sound made by the song thrush is as it breaks a snail's shell on a stone. I listened to this tapping one June night, the thrush being in bright light below a street lamp; doubtless it had a large brood to feed. To date, I have heard neither a blackbird nor a mistle thrush in full song at night, despite the intensity with which they will alarm if agitated.
Yet another common bird which will burst into snatches of song
during the night the dunnock. While roosting in
summer, perhaps in hawthorn or ivy, a vigorous male will make
its high-frequency, melodious warble if it is woken, I have the
impression that this song is more likely to occur if the roosting-site
is near to artificial illumination. I have heard the vocalisation
commence spontaneously, or apparently so, while on other occasions it
has been initiated by the roar of a speeding motor-cycle, by a
vehicle's back-fire, by a gust of strong wind or by a
sudden downfall of rain. Then, although it could hardly be influenced by street lighting very often, the grasshopper warbler will frequently reel during darkness; in this case, unlike the dunnock, it can probably be classed as a true nocturnal singer. Nevertheless, after a grasshopper warbler has stopped its sang soon after dusk and has apparently settled at roost, it does not require a big stimulus to trigger it into song again, especially on warm and sultry nights in June.
While blackbirds will alarm in darkness if alerted by a fox or cat, either of which will climb small trees or bushes after a bird, it could hardly be suggested that these mammals would clamber to the height of an average rookery to attack roosting or nestling rooks. Yet sometimes at dead of night a commotion of cawing will commence in an occupied rookery. This may be due to disturbance by a tawny owl, to be proved by watching the owl fly off, but often there is no obvious reason. Perhaps some rooks take to sleep-walking and doubtless that would be quite enough to upset a territorially-minded neighbour. Similarly, I have heard carrion crows croaking loudly while at roost, both in deep country and in urban zones. Then, jackdaws roosting in old quarries may suddenly utter "jack, jack" calls; here, foraging rats could be the culprits.
In woodland, one of the birds most easily upset at night is the woodpigeon; any slight disturbance will send it flying noisily from its sleeping perch and it will also make cooing sounds. I have also heard male cuckoos calling at night during May; usually this has not been the full song but just a few "cuck, cuck" notes were given, probably in response to an intruding tawny owl.
On open moorland or grassland nesting lapwings are upset, not uncommonly, by predatory mammals at night. Foxes, rats, stoats er hedgehogs all have a liking for sitting birds, chicks or eggs and all have nocturnal habits. Lapwings seem to be ever-vigilant; it is true that the nuptial song may be produced by the male at night, but the more urgent "pee-weet"call usually signifies that an enemy is approaching.
Lapwings may breed by the sides of lakes as well as on downland and they can be equally noisy in that situation if disturbed at night. In this habitat, their calls may be interspersed by the short, loud expletives of an annoyed moorhen, while coots can become remarkably vocal if they find their young to be threatened. In reed-beds territory-holding reed warblers often chatter and repeat their song cadences during darkness; such night singing, however, may well be precipitated by the passage of a hunting fox or even an otter. These sinister disturbers of the lakeside peace will, in the same way, stimulate the sedge warbler to chirp off its more varied song.
Frequently, tawny owls will upset the tranquility of a reed-bad or willow clump by plunging in to seize a sleeping starling or swallow; understandably, this causes vocal protests by the other bird residents. still, there are times when a tawny owl's visit leads to cessation of sound. On one occasion, when I was listening to a nightingale singing with vigour in hawthorn scrub, a tawny owl swung out of the night and dropped noiselessly into the foliage. Instantly, the nightingale was silenced and I expected the owl to emerge carrying the singer in its talons. However, after a few seconds the owl flew off without its prey and the nightingale's enchanted song was soon resumed, and at its full qua1it;y. Not a single note of alarm or anxiety had been uttered.
In contrast with land birds, those of the coastal marsh and the sea commonly vocalise at night. Many waders feed depending on the tidal conditions, not on the presence of daylight. Food-seeking estuarine birds such as curlews, oyetercatchers or black-headed gulls may call almost continuously, especially during moonlight. These sounds are often interrupted by the hard "kark" note of a heron. Again, calling is frequently heard at night from colonies of cliff-nesting kittiwakes or other sea birds; guillemots or razorbills might be other examples. Night intruders may initiate these cries, yet one would think there would be few mammals bold enough to venture on the sheer cliffs selected by kittiwakes.
Whooper Swans and other waterfowl vocalising at night, Caelaverock WWT, Scotland. Recorded by Richard Mudhar 24 January 2009 18:56
There is usually night clamour from the ground-breeding colonies of Arctic or common terns, whether on islets or on coastal shingle or dune sites; the noise, however, is normally intermittent and there are often periods of complete calm. A possible raider of mainland colonies is the hedgehog; it will take eggs and eat young, devouring the chick gradually yet relentlessly, while the bird is still alive. As might be imagined, this is accompanied by the harsh screams of diving terns; should an Arctic tern, in a dive, strike a hedgehog with its bill, the spines could inflict an unpleasant injury to the face of the bird. Other nocturnal ternery predators are foxes and rats; certainly these intruders are attacked and the sharp, pointed bill of the Arctic tern could be a weapon effective in deterring them. It is not possible to say if the terns are able to swoop with any precision on really dark nights, but without doubt they will do so if there is moonglow, however faint.
Returning to land, the hooting of tawny owls, like the barking of foxes, is part of the sound scene of the night and we do not often hear such calls by day. Yet tawny owls may call by day just as some day birds are heard at night, particularly if displaced from their roosting sites, If discovered and mobbed by small birds, such as chaffinches or tits, owls appear to take no notice whatsoever. But if a large bird of prey, a buzzard for instance, alights near the roost site the tawny owl will probably fly off and several sharp calls, '"Ku-ick, ku-ick', will probably be heard.
Like the tawny owl, the nightjars is a real bird of the night; personally, 1 have never heard it churr its mechanical song in full daylight although I have heard partial churring during dull periods of the day. Nevertheless, its alarm call would be uttered if it was put up from its day roost, although it is always a difficult bird to dislodge. In fact, I knew of one sitting hen nightjar which did not fly even though a farm tractor was driven over it; the bird continued to incubate between the tractor wheels.
Thus, the recordist must be prepared to tape the unexpected,
if he wants a true record of what is happening around him. For most of
the time the recordist cannot predict how wildlife will react in
changing circumstances; probably many of us can recall around sequences
which we failed to put on tape, even though we had our recording
apparatus with us in full working order. So often the hearing of calls
of species at what is thought to be the wrong season or at a strange
hour of the day seems to paralyse the recordist. Wildlife acoustic
behaviour is so
complex that the naturalist recordist cannot afford to neglect events which are not as expected.